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ENH: EBRSM: new elliptic-blending Reynolds-stress turbulence model
OpenCFD would like to acknowledge and thank Prof. Rémi Manceau, Dr. Michael Karl Stoellinger, and Dr. Ardalan Javadi for their contributions, elaborate suggestions and help, and critical recommendations. Highly appreciated.
Aim
Implement and evaluate the elliptic-blending Reynolds-stress turbulence models proposed by Manceau (2015) - Appendix C.
Methodology
Plane channel flow at ReTau=180, 395, 590 (Moser et al., 1991) and =4179 (Lozano-Duran & Jimenez, 2014)
NASA Turbulence Modelling Resource on various physics:
2DCC: 2D Convex curvature boundary layer
2DML: 2D Mixing layer
2DB: 2D Bump-in-channel
2DZP: 2D Zero pressure gradient flat plate
2DANW: 2D Airfoil near-wake
Results
Plane channel flow, ReTau=180
Plane channel flow, ReTau=4179
2DCC: 2D Convex curvature boundary layer
2DML: 2D Mixing Layer
Meta-data
EP#1805
linux64ClangDPInt32Opt (clang11)
linux64GccDPInt32Opt
linux64GccSPDPInt64Debug
Alltest: No new error
Discussion
In general, EBRSM yields better predictions for R and turbulence quantities in comparison to kOmegaSST model.
But not always: For example, for 2DML: 2D Mixing Layer, the R predictions of EBRSM is worse than those of kOmegaSST. The reason seems to be that the EBRSM could not reach the target convergence levels for this specific case.
Predictions for U are similar.
In general, less stable than kOmegaSST.
For example, 2DZP: 2D Zero pressure gradient flat plate and 2DANW: 2D Airfoil near-wake cases are unstable.
Initial values/initialisations seem to be important to
EBRSM in terms of numerical stability
and fidelity.
The two-step automatic initialisation method proposed by (Manceau (n.d.)) should be preferred
over precursor simulations.
Low-quality mesh cases are challenging,
especially meshes with high-aspect ratios
are prone to instabilities.
Max relaxation factor for R=0.4. Avoid R~O(0.05) at all costs.
Realizability conditions are not
automatically satisfied.
Multiphase and compressible cases are
not explored by the academia.
Future work
Test scope should be extended further for:
Multiphase-flow cases
Compressible flow cases
Dynamic-mesh cases
Overset meshes
Mesh (un)refinements
Collated-data format
Hybrid and single precisions
New methods should be developed to stabilise EBRSM for low-quality meshes.
