UFR 1-07 Evaluation: Difference between revisions
| Line 14: | Line 14: | ||
Figure 11 shows a snapshot of the flow field predicted by the CFD model | Figure 11 shows a snapshot of the flow field predicted by the CFD model | ||
of DesJardin | of DesJardin ''et al.'' [[UFR_1-07_References#1|[1]]]. With the coarse grid, the plume | ||
puffing frequency was found to be approximately 1.8 Hz, much higher | puffing frequency was found to be approximately 1.8 Hz, much higher | ||
than the frequency measured in the experiments of 1. | than the frequency measured in the experiments of 1.37 Hz. The | ||
predictions improved as the grid was refined, with the fine grid | predictions improved as the grid was refined, with the fine grid | ||
producing a frequency of 1.5 Hz. A similar frequency was obtained with | producing a frequency of 1.5 Hz. A similar frequency was obtained with | ||
or without an SGS model. DesJardin | or without an SGS model. DesJardin ''et al.'' [[UFR_1-07_References#1|[1]]] also presented | ||
results from a simulation with no SGS model and a very coarse mesh | results from a simulation with no SGS model and a very coarse mesh | ||
(220k nodes in total and only 30 cells across the source diameter). | (220k nodes in total and only 30 cells across the source diameter). | ||
This produced a puffing frequency of 1.7 Hz, which they considered to | This produced a puffing frequency of 1.7 Hz, which they considered to | ||
be an adequate estimate for engineering purposes, although the axial | be an adequate estimate for engineering purposes, although the axial | ||
velocity in this case was overpredicted by nearly a factor of two. | velocity in this case was overpredicted by nearly a factor of two. | ||
{{UFRHeader | {{UFRHeader | ||
Revision as of 18:54, 12 July 2010
Unsteady Near-Field Plumes
Underlying Flow Regime 1-07
Comparison of DesJardin et al. [1] CFD Calculations with Experiments
Figure 11 shows a snapshot of the flow field predicted by the CFD model of DesJardin et al. [1]. With the coarse grid, the plume puffing frequency was found to be approximately 1.8 Hz, much higher than the frequency measured in the experiments of 1.37 Hz. The predictions improved as the grid was refined, with the fine grid producing a frequency of 1.5 Hz. A similar frequency was obtained with or without an SGS model. DesJardin et al. [1] also presented results from a simulation with no SGS model and a very coarse mesh (220k nodes in total and only 30 cells across the source diameter). This produced a puffing frequency of 1.7 Hz, which they considered to be an adequate estimate for engineering purposes, although the axial velocity in this case was overpredicted by nearly a factor of two.
Contributed by: Simon Gant — UK Health & Safety Laboratory
© copyright ERCOFTAC 2010