UFR 2-12 Best Practice Advice: Difference between revisions
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of all the UFR characteristics. | of all the UFR characteristics. | ||
Whether this is reached or not in a simulation should be checked by: | Whether this is reached or not in a simulation should be checked by: | ||
*Obtaining a visual impression of the unsteadiness of the shear layer separated from the upstream cylinder and of a range of spatial scales present in its wake and in the wake of the downstream cylinder using e.g. a snapshot of isosurface of ''λ<sub>2</sub> ("swirl") or Q-criterion (see [[ | *Obtaining a visual impression of the unsteadiness of the shear layer separated from the upstream cylinder and of a range of spatial scales present in its wake and in the wake of the downstream cylinder using e.g. a snapshot of isosurface of ''λ''<sub>2</sub> ("swirl") or Q-criterion (see [[UFR_2_12_Evaluation#figure4|Figure 4]] for an example of the former) and vorticity contours ([[UFR_2-12_Evaluation#figure11|Figure 11]]). | ||
*Confirming a mixed tonal and broadband nature of the pressure signals on the surface of the cylinders by their spectral analysis ([[ | *Confirming a mixed tonal and broadband nature of the pressure signals on the surface of the cylinders by their spectral analysis ([[UFR_2-12_Evaluation#figure16|Figure 16]]). | ||
== Numerical Modelling == | == Numerical Modelling == | ||
Revision as of 11:39, 30 October 2012
Turbulent Flow Past Two-Body Configurations
Flows Around Bodies
Underlying Flow Regime 2-12
Best Practice Advice
NOTE: the BPA formulated below are overall well in line with conclusions based on the outcome of BANC-I [5] and not yet published results of BANC-II.
Key Physics
The key physical features of this UFR are separation of the turbulent shear layer from the upstream cylinder, free shear layer roll-up and chaotization, interaction of the essentially unsteady wake of the upstream cylinder with the downstream one, and massively separated wake of the downstream cylinder. It is found that it is necessary to capture these challenging features in a simulation claiming a reliable prediction of all the UFR characteristics. Whether this is reached or not in a simulation should be checked by:
- Obtaining a visual impression of the unsteadiness of the shear layer separated from the upstream cylinder and of a range of spatial scales present in its wake and in the wake of the downstream cylinder using e.g. a snapshot of isosurface of λ2 ("swirl") or Q-criterion (see Figure 4 for an example of the former) and vorticity contours (Figure 11).
- Confirming a mixed tonal and broadband nature of the pressure signals on the surface of the cylinders by their spectral analysis (Figure 16).
Numerical Modelling
- Discretisation method
- Grids and grid resolution
Physical Modelling
- Turbulence modelling
- Transition modelling
- Near-wall modelling
- Other modelling
Application Uncertainties
Summarise any aspects of the UFR model set-up which are subject to uncertainty and to which the assessment parameters are particularly sensitive (e.g location and nature of transition to turbulence; specification of turbulence quantities at inlet; flow leakage through gaps etc.)
Recommendations for Future Work
Propose further studies which will improve the
quality or scope of the BPA and perhaps bring it up to date. For example,
perhaps further calculations of the test-case should be performed
employing more recent, highly promising models of turbulence (e.g Spalart
and Allmaras, Durbin's v2f, etc.). Or perhaps new experiments should be
undertaken for which the values of key parameters (e.g. pressure gradient
or streamline curvature) are much closer to those encountered in real
application challenges.
Contributed by: A. Garbaruk, M. Shur and M. Strelets — New Technologies and Services LLC (NTS) and St.-Petersburg State Polytechnic University
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