https://kbwiki.ercoftac.org/w/index.php?title=UFR_3-35_Best_Practice_Advice&feed=atom&action=history UFR 3-35 Best Practice Advice - Revision history 2024-03-28T15:45:18Z Revision history for this page on the wiki MediaWiki 1.39.2 https://kbwiki.ercoftac.org/w/index.php?title=UFR_3-35_Best_Practice_Advice&diff=39066&oldid=prev Dave.Ellacott: Dave.Ellacott moved page Lib:UFR 3-35 Best Practice Advice to UFR 3-35 Best Practice Advice over redirect 2020-11-04T15:52:46Z <p>Dave.Ellacott moved page <a href="/w/index.php/Lib:UFR_3-35_Best_Practice_Advice" class="mw-redirect" title="Lib:UFR 3-35 Best Practice Advice">Lib:UFR 3-35 Best Practice Advice</a> to <a href="/w/index.php/UFR_3-35_Best_Practice_Advice" title="UFR 3-35 Best Practice Advice">UFR 3-35 Best Practice Advice</a> over redirect</p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <tr class="diff-title" lang="en"> <td colspan="1" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="1" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 15:52, 4 November 2020</td> </tr><tr><td colspan="2" class="diff-notice" lang="en"><div class="mw-diff-empty">(No difference)</div> </td></tr></table> Dave.Ellacott https://kbwiki.ercoftac.org/w/index.php?title=UFR_3-35_Best_Practice_Advice&diff=39048&oldid=prev Wolfgang.Rodi: /* Recommendations for Future Work */ 2020-10-30T14:17:44Z <p><span dir="auto"><span class="autocomment">Recommendations for Future Work</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:17, 30 October 2020</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l43">Line 43:</td> <td colspan="2" class="diff-lineno">Line 43:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Performing a converged Direct Numerical Simulation would end all discussions about models and is - in our opinion - not far out of reach to date (2020). Further, considering surface roughness might give additional insight into the interaction of the wall jet with the wall.  </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Performing a converged Direct Numerical Simulation would end all discussions about models and is - in our opinion - not far out of reach to date (2020). Further, considering surface roughness might give additional insight into the interaction of the wall jet with the wall.  </div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The experiments could be improved by stereoscopic or tomographic PIV to acquire three dimensional data sets. Furthermore, the temporal resolution could be increased<del style="font-weight: bold; text-decoration: none;">, </del>in order to analyse the time scales of the horseshoe vortex system. The experimental setup can be improved by providing the light sheet from below passing through the transparent bottom plate, while the PIV camera(s) are mounted at the side outside of the flume.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The experiments could be improved by stereoscopic or tomographic PIV to acquire three<ins style="font-weight: bold; text-decoration: none;">-</ins>dimensional data sets. Furthermore, the temporal resolution could be increased in order to analyse the time scales of the horseshoe vortex system. The experimental setup can be improved by providing the light sheet from below passing through the transparent bottom plate, while the PIV camera(s) are mounted at the side outside of the flume.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> </table> Wolfgang.Rodi https://kbwiki.ercoftac.org/w/index.php?title=UFR_3-35_Best_Practice_Advice&diff=39047&oldid=prev Wolfgang.Rodi: /* Application Uncertainties */ 2020-10-30T14:17:08Z <p><span dir="auto"><span class="autocomment">Application Uncertainties</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:17, 30 October 2020</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l36">Line 36:</td> <td colspan="2" class="diff-lineno">Line 36:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Application Uncertainties ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Application Uncertainties ==</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>When simulating this flow configuration, we <del style="font-weight: bold; text-decoration: none;">address </del>the largest uncertainties to the inflow conditions of the approach flow and <del style="font-weight: bold; text-decoration: none;">to </del>the representation of the water surface. Both<del style="font-weight: bold; text-decoration: none;">, </del>numerical and experimental approaches<del style="font-weight: bold; text-decoration: none;">, </del>face the challenge <del style="font-weight: bold; text-decoration: none;">in </del>generating a fully developed turbulent <del style="font-weight: bold; text-decoration: none;">boundary layer</del>. Even though we intended to reproduce identical flow conditions and validated both of our methods (PIV and LES) by comparison <del style="font-weight: bold; text-decoration: none;">to </del>results in the literature, we observed differences in our results concerning the size and location of the horseshoe vortex <del style="font-weight: bold; text-decoration: none;">for example </del>(see Fig. 6), which we attribute to the uncertainties in the structure of secondary flows or in modelling the water surface.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>When simulating this flow configuration, we <ins style="font-weight: bold; text-decoration: none;">experience </ins>the largest uncertainties <ins style="font-weight: bold; text-decoration: none;">with regard </ins>to the inflow conditions of the approach flow and the representation of the water surface. Both numerical and experimental approaches face the challenge <ins style="font-weight: bold; text-decoration: none;">of </ins>generating a fully developed turbulent <ins style="font-weight: bold; text-decoration: none;">open-channel flow</ins>. Even though we intended to reproduce identical flow conditions and validated both of our methods (PIV and LES) by comparison <ins style="font-weight: bold; text-decoration: none;">with </ins>results in the literature, we observed differences in our results<ins style="font-weight: bold; text-decoration: none;">, e.g. </ins>concerning the size and location of the horseshoe vortex (see Fig. 6), which we attribute to the uncertainties in the structure of <ins style="font-weight: bold; text-decoration: none;">prevailing </ins>secondary flows or in modelling the water surface.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Another uncertainty is the roughness of the wall and its effect on the flow. It is our understanding that at the moment little is known on this issue.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Another uncertainty is the roughness of the wall and its effect on the flow. It is our understanding that at the moment little is known on this issue.</div></td></tr> </table> Wolfgang.Rodi https://kbwiki.ercoftac.org/w/index.php?title=UFR_3-35_Best_Practice_Advice&diff=39046&oldid=prev Wolfgang.Rodi: /* Measurement issues */ 2020-10-30T14:10:47Z <p><span dir="auto"><span class="autocomment">Measurement issues</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:10, 30 October 2020</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l33">Line 33:</td> <td colspan="2" class="diff-lineno">Line 33:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Measurement issues ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Measurement issues ==</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The horseshoe vortex system is a complex three-dimensional flow configuration. Therefore, the two-dimensional data acquisition method represents a limitation as the out-of-plane velocity component leads to a considerable loss of particles. The number of valid samples suffered from this issue in combination with the low seeding density resulting from the large size of the flume. To overcome this issue, we additionally evaluated the PIV images with a &lt;math&gt;32\times32\mathrm{px}&lt;/math&gt; grid. Whenever the instantaneous velocity fields based on a &lt;math&gt;16\times16\mathrm{px}&lt;/math&gt; grid revealed a missing vector, the corresponding vector of the coarser evaluation was taken as a substitute, if possible. In this way, we could improve the number of valid samples and still keep the spatial resolution high.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The horseshoe vortex system is a complex three-dimensional flow configuration. Therefore, the two-dimensional data acquisition method represents a limitation as the out-of-plane velocity component leads to a considerable loss of particles. The number of valid samples suffered from this issue in combination with the low seeding density resulting from the large size of the flume. To overcome this issue, we additionally evaluated the PIV images with a &lt;math&gt;32\times32\mathrm{px}&lt;/math&gt; grid. Whenever the instantaneous velocity fields based on a &lt;math&gt;16\times16\mathrm{px}&lt;/math&gt; grid revealed a missing vector, the corresponding vector of the coarser evaluation was taken as a substitute, if possible. In this way, we could improve the number of valid samples and still keep the spatial resolution high.</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>However, the spatial resolution of the PIV data was too coarse to resolve the velocity gradient correctly. Therefore, a single pixel evaluation is recommended, for capturing the wall<del style="font-weight: bold; text-decoration: none;">-</del>shear stress correctly.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>However, the spatial resolution of the PIV data was too coarse to resolve the velocity gradient correctly. Therefore, a single pixel evaluation is recommended, for capturing the wall shear stress correctly.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Application Uncertainties ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Application Uncertainties ==</div></td></tr> </table> Wolfgang.Rodi https://kbwiki.ercoftac.org/w/index.php?title=UFR_3-35_Best_Practice_Advice&diff=39045&oldid=prev Wolfgang.Rodi: /* Measurement issues */ 2020-10-30T14:10:05Z <p><span dir="auto"><span class="autocomment">Measurement issues</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:10, 30 October 2020</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l32">Line 32:</td> <td colspan="2" class="diff-lineno">Line 32:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Measurement issues ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Measurement issues ==</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The horseshoe vortex system is a complex three-dimensional flow configuration. Therefore, the two-dimensional data acquisition method <del style="font-weight: bold; text-decoration: none;">is </del>a limitation as the out-of-plane velocity component leads to a considerable loss of particles. The number of valid samples suffered from this issue in combination <del style="font-weight: bold; text-decoration: none;">of </del>the low seeding density resulting from the large size of the flume. To overcome this issue, we additionally evaluated the PIV images with a &lt;math&gt;32\times32\mathrm{px}&lt;/math&gt; grid. Whenever the instantaneous velocity fields based on a &lt;math&gt;16\times16\mathrm{px}&lt;/math&gt; grid revealed a missing vector, the corresponding vector of the coarser evaluation was taken as a substitute, if possible. In this way, we could improve the number of valid samples and still keep the spatial resolution high.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The horseshoe vortex system is a complex three-dimensional flow configuration. Therefore, the two-dimensional data acquisition method <ins style="font-weight: bold; text-decoration: none;">represents </ins>a limitation as the out-of-plane velocity component leads to a considerable loss of particles. The number of valid samples suffered from this issue in combination <ins style="font-weight: bold; text-decoration: none;">with </ins>the low seeding density resulting from the large size of the flume. To overcome this issue, we additionally evaluated the PIV images with a &lt;math&gt;32\times32\mathrm{px}&lt;/math&gt; grid. Whenever the instantaneous velocity fields based on a &lt;math&gt;16\times16\mathrm{px}&lt;/math&gt; grid revealed a missing vector, the corresponding vector of the coarser evaluation was taken as a substitute, if possible. In this way, we could improve the number of valid samples and still keep the spatial resolution high.</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>However, the spatial resolution of the PIV data was too coarse to resolve the velocity gradient correctly. Therefore, a single pixel evaluation is recommended, <del style="font-weight: bold; text-decoration: none;">in order to capture </del>the wall-shear stress correctly.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>However, the spatial resolution of the PIV data was too coarse to resolve the velocity gradient correctly. Therefore, a single pixel evaluation is recommended, <ins style="font-weight: bold; text-decoration: none;">for capturing </ins>the wall-shear stress correctly.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Application Uncertainties ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Application Uncertainties ==</div></td></tr> </table> Wolfgang.Rodi https://kbwiki.ercoftac.org/w/index.php?title=UFR_3-35_Best_Practice_Advice&diff=39044&oldid=prev Wolfgang.Rodi: /* Physical Modelling */ 2020-10-30T14:07:57Z <p><span dir="auto"><span class="autocomment">Physical Modelling</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:07, 30 October 2020</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l23">Line 23:</td> <td colspan="2" class="diff-lineno">Line 23:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Physical Modelling ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Physical Modelling ==</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>This flow case represents a highly complex three-dimensional turbulent flow which shows several characteristics making it difficult to be represented by numerical methods based on the Reynolds Averaged Navier Stokes (RANS) equations. There is the dynamics of the horseshoe vortex which <del style="font-weight: bold; text-decoration: none;">tumbles </del>in horizontal direction and produces bimodal velocity distributions near the wall (as shown by many authors). The production of turbulent kinetic energy is far from a standard shear stress production observed in canonical boundary layers. In some important parts of the flow (in the wall jet where the largest wall shear stress values can be found) there is even a negative TKE production due to the strong flow acceleration. The levels of streamwise fluctuations under the horseshoe vortex seem to depend on the level of TKE in the wall jet in which a balance between the pressure transport and the negative normal stress production term is observed. In other regions (around the horseshoe vortex) it seems that the pressure and turbulent diffusive transport terms cancel each other and should be modeled as a whole. This all indicates that RANS modeling of this flow is a non-trivial task. The turbulent viscosity might be strongly overestimated by standard two equation models, especially in the wall jet.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>This flow case represents a highly complex three-dimensional turbulent flow which shows several characteristics making it difficult to be represented by numerical methods based on the Reynolds Averaged Navier Stokes (RANS) equations. There is the dynamics of the horseshoe vortex which <ins style="font-weight: bold; text-decoration: none;">oscillates </ins>in horizontal direction and produces bimodal velocity distributions near the wall (as shown by many authors). The production of turbulent kinetic energy <ins style="font-weight: bold; text-decoration: none;">(TKE) </ins>is far from a standard shear stress production observed in canonical boundary layers. In some important parts of the flow (in the wall jet where the largest wall shear stress values can be found) there is even a negative TKE production due to the strong flow acceleration. The levels of streamwise fluctuations under the horseshoe vortex seem to depend on the level of TKE in the wall jet in which a balance between the pressure transport and the negative normal stress production term is observed. In other regions (around the horseshoe vortex) it seems that the pressure and turbulent diffusive transport terms cancel each other and should be modeled as a whole. This all indicates that RANS modeling of this flow is a non-trivial task. The turbulent viscosity might be strongly overestimated by standard two equation models, especially in the wall jet.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>For eddy-resolving turbulence <del style="font-weight: bold; text-decoration: none;">modeling </del>strategies, several observations might be of importance. The turbulence is far from an isotropic state or from equilibrium. However, around the horseshoe vortex, the gradients of fluctuations in the main flow direction contribute to the dissipation in the same way as gradients in the vertical direction (Schanderl &amp; Manhart 2018). This implies that strongly anisotropic grids are probably not suited to capture the physics around the horseshoe vortex in a sufficiently accurate way. We observed a relatively strong grid dependence of the results, although the SGS contribution was relatively small.  </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>For eddy-resolving turbulence <ins style="font-weight: bold; text-decoration: none;">calcuation </ins>strategies, several observations might be of importance. The turbulence is far from an isotropic state or from equilibrium. However, around the horseshoe vortex, the gradients of fluctuations in the main flow direction contribute to the dissipation in the same way as gradients in the vertical direction (Schanderl &amp; Manhart 2018). This implies that strongly anisotropic grids are probably not suited to capture the physics around the horseshoe vortex in a sufficiently accurate way. We observed a relatively strong grid dependence of the results, although the SGS contribution was relatively small.  </div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>According to our observation, a subgrid-scale model needs to be able to adapt itself to the laminar-like behaviour of the wall layer under the wall jet. <del style="font-weight: bold; text-decoration: none;">Additionally</del>, we have no hope that explicit wall models relying on the logarithmic law of the wall can give an accurate correlation of the wall shear stress with a velocity value <del style="font-weight: bold; text-decoration: none;">in </del>a wall distance in inner coordinate corresponding to the logarithmic layer (Schanderl et al. 2017a).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>According to our observation, a subgrid-scale model needs to be able to adapt itself to the laminar-like behaviour of the wall layer under the wall jet. <ins style="font-weight: bold; text-decoration: none;">Further</ins>, we have no hope that explicit wall models relying on the logarithmic law of the wall can give an accurate correlation of the wall shear stress with a velocity value <ins style="font-weight: bold; text-decoration: none;">at </ins>a wall distance in inner coordinate corresponding to the logarithmic layer (Schanderl et al. 2017a).</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>For designing a grid for a DNS, it is important to <del style="font-weight: bold; text-decoration: none;">learn </del>that estimating the Kolmogorov scale by &lt;math&gt; D/Re^{3/4} &lt;/math&gt; gives a conservative value and <del style="font-weight: bold; text-decoration: none;">is in </del>the correct order of magnitude (Schanderl &amp; Manhart 2018).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>For designing a grid for a DNS, it is important to <ins style="font-weight: bold; text-decoration: none;">note </ins>that estimating the Kolmogorov scale by &lt;math&gt; D/Re^{3/4} &lt;/math&gt; gives a conservative value and <ins style="font-weight: bold; text-decoration: none;">yields </ins>the correct order of magnitude (Schanderl &amp; Manhart 2018).</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Measurement issues ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Measurement issues ==</div></td></tr> </table> Wolfgang.Rodi https://kbwiki.ercoftac.org/w/index.php?title=UFR_3-35_Best_Practice_Advice&diff=39043&oldid=prev Wolfgang.Rodi: /* Numerical Modelling Issues */ 2020-10-30T14:03:02Z <p><span dir="auto"><span class="autocomment">Numerical Modelling Issues</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:03, 30 October 2020</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l15">Line 15:</td> <td colspan="2" class="diff-lineno">Line 15:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Numerical Modelling Issues ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Numerical Modelling Issues ==</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">A </del>fully turbulent open channel flow <del style="font-weight: bold; text-decoration: none;">has to be modeled </del>at the inflow plane which should be placed at least 10 diameters upstream of the cylinder. It is essential to have a realistic turbulence structure and secondary flow at the inflow plane. For eddy resolving simulation strategies (DNS, LES and DES) this implies modeling or generating a fully developed open channel flow which is best achieved by a precursor simulation.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Conditions corresponding to </ins>fully turbulent open channel flow <ins style="font-weight: bold; text-decoration: none;">have been applied </ins>at the inflow plane which should be placed at least 10 diameters upstream of the cylinder. It is essential to have a realistic turbulence structure and secondary flow at the inflow plane. For eddy resolving simulation strategies (DNS, LES and DES) this implies modeling or generating a fully developed open channel flow which is best achieved by a precursor simulation.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The downstream extent of the domain largely <del style="font-weight: bold; text-decoration: none;">depends </del>on the region of interest and should be placed far enough from the recirculation downstream of the cylinder to avoid instabilities and upstream-propagated waves. According to the authors' estimation this might vary depending on the specific type of the numerical scheme and outflow boundary condition.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The downstream extent of the <ins style="font-weight: bold; text-decoration: none;">computation </ins>domain <ins style="font-weight: bold; text-decoration: none;">depends </ins>largely on the region of interest and should be placed far enough from the recirculation <ins style="font-weight: bold; text-decoration: none;">zone </ins>downstream of the cylinder to avoid instabilities and upstream-propagated waves. According to the authors' estimation this might vary depending on the specific type of the numerical scheme and outflow boundary condition.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>A high spatial resolution is required to capture the horseshoe vortex dynamics and the wall shear stress. For the Reynolds number considered, a wall-normal resolution of &lt;math&gt; D/1000&lt;/math&gt; was necessary to obtain converged wall shear stresses. This high resolution was necessary because the wall jet does not follow the law of the wall for turbulent boundary layers and therefore needs to be fully resolved for wall shear stress <del style="font-weight: bold; text-decoration: none;">calculations</del>. A realistic representation of the junction vortex also requires a fine resolution in the horizontal directions.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>A high spatial resolution is required to capture the horseshoe vortex dynamics and the wall shear stress. For the Reynolds number considered, a wall-normal resolution of &lt;math&gt; D/1000&lt;/math&gt; was necessary to obtain converged wall shear stresses. This high resolution was necessary because the wall jet does not follow the law of the wall for turbulent boundary layers and therefore needs to be fully resolved for <ins style="font-weight: bold; text-decoration: none;">calculating the </ins>wall shear stress. A realistic representation of the junction vortex also requires a fine resolution in the horizontal directions.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Physical Modelling ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Physical Modelling ==</div></td></tr> </table> Wolfgang.Rodi https://kbwiki.ercoftac.org/w/index.php?title=UFR_3-35_Best_Practice_Advice&diff=39042&oldid=prev Wolfgang.Rodi: /* Key Physics */ 2020-10-30T13:54:32Z <p><span dir="auto"><span class="autocomment">Key Physics</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 13:54, 30 October 2020</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l12">Line 12:</td> <td colspan="2" class="diff-lineno">Line 12:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The wall distance of the horseshoe vortex is about &lt;math&gt; 0.06D &lt;/math&gt;, the thickness of the wall jet between the cylinder and the horseshoe vortex center is smaller than &lt;math&gt; 0.01D &lt;/math&gt;. This means that the key physics take place in a very thin layer in front of the cylinder. A simulation or a measurement not resolving this layer might strongly miss some key features such as the levels of the wall shear stress and the large levels of the streamwise velocity fluctuations and their bimodal character under the horseshoe vortex.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The wall distance of the horseshoe vortex is about &lt;math&gt; 0.06D &lt;/math&gt;, the thickness of the wall jet between the cylinder and the horseshoe vortex center is smaller than &lt;math&gt; 0.01D &lt;/math&gt;. This means that the key physics take place in a very thin layer in front of the cylinder. A simulation or a measurement not resolving this layer might strongly miss some key features such as the levels of the wall shear stress and the large levels of the streamwise velocity fluctuations and their bimodal character under the horseshoe vortex.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>It has been demonstrated that Reynolds shear stresses <del style="font-weight: bold; text-decoration: none;">are </del>small below the velocity maximum of the wall jet between the cylinder and the horseshoe vortex. This indicates a laminar-like behavior of the velocity profile below the jet's velocity maximum. As a consequence, conventional wall models relying on the logarithmic law of the wall will have difficulties to model the wall shear stress in this region.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>It has been demonstrated that <ins style="font-weight: bold; text-decoration: none;">the </ins>Reynolds shear stresses <ins style="font-weight: bold; text-decoration: none;">is </ins>small below the velocity maximum of the wall jet between the cylinder and the horseshoe vortex. This indicates a laminar-like behavior of the velocity profile below the jet's velocity maximum. As a consequence, conventional wall models relying on the logarithmic law of the wall will have difficulties to model the wall shear stress in this region.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Numerical Modelling Issues ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Numerical Modelling Issues ==</div></td></tr> </table> Wolfgang.Rodi https://kbwiki.ercoftac.org/w/index.php?title=UFR_3-35_Best_Practice_Advice&diff=38994&oldid=prev Munich: /* Recommendations for Future Work */ 2020-10-08T18:53:26Z <p><span dir="auto"><span class="autocomment">Recommendations for Future Work</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:53, 8 October 2020</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l41">Line 41:</td> <td colspan="2" class="diff-lineno">Line 41:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Recommendations for Future Work ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Recommendations for Future Work ==</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Performing a converged Direct Numerical Simulation would end all discussions about models and is - in our opinion - not far out of reach to date (<del style="font-weight: bold; text-decoration: none;">2019</del>). Further, considering surface roughness might give additional insight into the interaction of the wall jet with the wall.  </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Performing a converged Direct Numerical Simulation would end all discussions about models and is - in our opinion - not far out of reach to date (<ins style="font-weight: bold; text-decoration: none;">2020</ins>). Further, considering surface roughness might give additional insight into the interaction of the wall jet with the wall.  </div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The experiments could be improved by stereoscopic or tomographic PIV to acquire three dimensional data sets. Furthermore, the temporal resolution could be increased, in order to analyse the time scales of the horseshoe vortex system. The experimental setup can be improved by providing the light sheet from below passing through the transparent bottom plate, while the PIV camera(s) are mounted at the side outside of the flume.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The experiments could be improved by stereoscopic or tomographic PIV to acquire three dimensional data sets. Furthermore, the temporal resolution could be increased, in order to analyse the time scales of the horseshoe vortex system. The experimental setup can be improved by providing the light sheet from below passing through the transparent bottom plate, while the PIV camera(s) are mounted at the side outside of the flume.</div></td></tr> </table> Munich https://kbwiki.ercoftac.org/w/index.php?title=UFR_3-35_Best_Practice_Advice&diff=38993&oldid=prev Munich: /* Application Uncertainties */ 2020-10-08T18:48:16Z <p><span dir="auto"><span class="autocomment">Application Uncertainties</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:48, 8 October 2020</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l37">Line 37:</td> <td colspan="2" class="diff-lineno">Line 37:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Application Uncertainties ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Application Uncertainties ==</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>When simulating this flow configuration, we address the largest uncertainties to the inflow conditions of the approach flow and to the representation of the water surface. Both, numerical and experimental approaches, face the challenge in generating a fully developed turbulent boundary layer. Even though we intended to reproduce identical flow conditions and validated both of our methods (PIV and LES) by comparison to results in the literature, we observed differences in our results concerning the size and location of the horseshoe vortex for example (see Fig. 6), which we attribute to the uncertainties in the structure of secondary flows or in modelling the water surface.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>When simulating this flow configuration, we address the largest uncertainties to the inflow conditions of the approach flow and to the representation of the water surface. Both, numerical and experimental approaches, face the challenge in generating a fully developed turbulent boundary layer. Even though we intended to reproduce identical flow conditions and validated both of our methods (PIV and LES) by comparison to results in the literature, we observed differences in our results concerning the size and location of the horseshoe vortex for example (see Fig. 6), which we attribute to the uncertainties in the structure of secondary flows or in modelling the water surface.</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Another uncertainty is the roughness of the wall and its effect on the flow. It is our understanding that at the moment little is known on this issue.</ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Recommendations for Future Work ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Recommendations for Future Work ==</div></td></tr> </table> Munich