ENH: resolutionIndex: new function object to evaluate LES/DES resolution

Acknowledgement

OpenCFD would like to acknowledge and thank Prof. Ismail Celik for his contributions, elaborate suggestions and help, and critical recommendations. Highly appreciated.

Problem statement

Grid independency studies and grid adaptation for implicit LES/DES are nontrivial and intractable due to the inherent coupling between spatial resolution and subgrid-scale modelling.

Problem solution

• In the literature, various metrics which do not use any experimental or DNS data and which is based on a single mesh were introduced.
• To enable assessments for LES/DES resolution, a single-mesh resolution index with three submodels is introduced:
  • Pope (2000)'s index using turbulent kinetic energy variables,
  • Celik et al. (2005) and Celik et al. (2009)'s index using
    • Effective Kolmogorov length scale, and
    • Effective viscosity.

Theory

Usage

Tests

resolutionIndex-tests.zip

Results

Discussion

• Resolution-index models need good estimators for the subgrid-scale turbulent kinetic energy (ksgs) field.
  • The DES models of SpalartAllmaras seem to produce zero-valued ksgs fields – Bug ticket is issued: GL2620
• DES models may need a chain of operations – see 'system/{controlDict,FOresolutionIndex}' in DES cases in order to mask out the RANS regions.

References

• Pope, S. B. (2000). Turbulent flows. Cambridge, UK: Cambridge Univ. Press
• Celik, I. B., Cehreli Z. N., Yavuz I. (2005). Index of resolution quality for large eddy simulations. Journal of Fluids Engineering. 127:949–958.
• Celik, I., Klein, M., & Janicka, J. (2009). Assessment measures for engineering LES applications. Journal of fluids engineering, 131(3)

Metadata

EP#1997

• linux64ClangDPInt32Opt (clang13)
• linux64GccDPInt32Opt
• linux64GccSPDPInt64Debug
• Alltest: No new error