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

changed milestone to %v2212

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requested review from @mark

assigned to @andy

added 2 commits

• 8775749e - ENH: RASModelBase: new base class for RANS models
• 4034b81e - ENH: resolutionIndex: new function object to evaluate LES/DES resolution

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and the Make/files adjustment seems to missing somewhere?

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• 3306e19f - ENH: RASModelBase: new base class for RANS models
• 60c7a5f5 - ENH: resolutionIndex: new function object to evaluate LES/DES resolution

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marked the checklist item linux64GccSPDPInt64Debug as completed

marked the checklist item Alltest: No new error as completed

added 36 commits

• 60c7a5f5...90b61429 - 34 commits from branch develop
• 13606d4e - ENH: RASModelBaseName: new type name for RANS models
• 8ba1156a - ENH: resolutionIndex: new function object to evaluate LES/DES resolution

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mentioned in commit 9f9b8fb6

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@kuti @andy - I think that this TemplateName stuff added too much confusion. With the last rebase we will now have unresolved link symbols since AFAICT nothing defines the RASModelBaseName::typeName or RASModelBaseName::debug

If we are to fix this, why don't we also place the coeffs dictionary and the limits (kMin, epsilonMin, ...) into the base class. They are template invariant and arguably a base component for various RAS models.

If no one else wants to, I will do it.

Looks like we're missing the RASModelBaseName.C file

namespace Foam
{
    defineTypeNameAndDebug(RASModelBaseName, 0);
}

For the moment, I think we only need a mechanism to deduce the type of the chosen turbulence-modelling form (i.e. RANS, DES and LES.)

Also, the preference from my side is to restructure the TurbulenceModel (or any other physics-oriented hierarchy) as a whole according to well-thought abstraction levels that are thoroughly discussed by community/experts.