View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0001930 | OpenFOAM | [All Projects] Bug | public | 2015-11-29 20:19 | 2015-11-29 21:29 |
| Reporter | wyldckat | Assigned To | henry | ||
| Priority | low | Severity | text | Reproducibility | N/A |
| Status | resolved | Resolution | fixed | ||
| Product Version | dev | ||||
| Fixed in Version | |||||
| Summary | 0001930: Default parameters in nutWallFunction are undocumented, update attached | ||||
| Description | This week at work, my colleague Pedro Freitas and I did some investigating into the values for "kappa" and "E" that is used by default in "nutWallFunctionFvPatchScalarField.C", because we were using another pair of values of "kappa=0.41" and "E=8.432" for smooth wall analytical expressions, which many people defend are better values based on experimental data. After some archaeological investigation into the OpenFOAM-history repository, I found that the latest values were introduced in this commit: https://github.com/OpenCFD/OpenFOAM-history/commit/704b3304dc86c7955d6e791ee223254186788c9a - which has the commit comment: «selecting common kappa=0.41 and E=9.8 (ref. Verst+Malal)» Attached is the file "nutWallFunctionFvPatchScalarField.H" for OpenFOAM-dev (might be also usable in 3.0.x?) that has the updated description that includes this information: \heading Patch usage \table Property | Description | Required | Default value Cmu | Cmu coefficient | no | 0.09 kappa | Von Karman constant | no | 0.41 E | E coefficient | no | 9.8 \endtable Examples of the boundary condition specification: \verbatim myPatch { type nutWallFunction; value uniform 0.0; } Reference for the default model coefficients: \verbatim H. Versteeg, W. Malalasekera An Introduction to Computational Fluid Dynamics: The Finite Volume Method, subsection "3.5.2 k-epsilon model" \endverbatim | ||||
| Additional Information | For complementing information on this topic, regarding what values should be used for kappa and E, lead us to the paper "Estimating the value of von Kármán’s constant in turbulent pipe flow", by S. C. C. Bailey, M. Vallikivi, M. Hultmark and A. J. Smits - doi:10.1017/jfm.2014.208 - http://fluids.princeton.edu/pubs/Bailey_et_al_2014.pdf There we can find out right on the introduction the large variety of kappa and E pairs that can be used in several situations. In addition, in Figure 5 is shown how much these values can vary depending on a series of flow scenarios, therefore... the pseudo-magical numbers used by OpenFOAM in "nutWallFunction" are the ones from the aforementioned book and that settles the issue :) | ||||
| Tags | No tags attached. | ||||
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nutWallFunctionFvPatchScalarField.H (5,437 bytes) |
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Ooops... I lost a "\endverbatim" when adding the book reference :( |
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nutWallFunctionFvPatchScalarField_v2.H (5,454 bytes) |
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Attached the rectified file "nutWallFunctionFvPatchScalarField_v2.H", for replacing "src/TurbulenceModels/turbulenceModels/derivedFvPatchFields/wallFunctions/nutWallFunctions/nutWallFunction/nutWallFunctionFvPatchScalarField.H" |
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Resolved in OpenFOAM-dev by commit 69f0a5e316ee9f222be974f4c459d09e77487c5a Resolved in OpenFOAM-3.0.x by commit 82270c6e4cbce65a3cb04d6043a367bd71811813 |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2015-11-29 20:19 | wyldckat | New Issue | |
| 2015-11-29 20:19 | wyldckat | Status | new => assigned |
| 2015-11-29 20:19 | wyldckat | Assigned To | => henry |
| 2015-11-29 20:19 | wyldckat | File Added: nutWallFunctionFvPatchScalarField.H | |
| 2015-11-29 20:22 | wyldckat | Note Added: 0005686 | |
| 2015-11-29 20:22 | wyldckat | File Added: nutWallFunctionFvPatchScalarField_v2.H | |
| 2015-11-29 20:23 | wyldckat | Note Added: 0005687 | |
| 2015-11-29 21:29 | henry | Note Added: 0005689 | |
| 2015-11-29 21:29 | henry | Status | assigned => resolved |
| 2015-11-29 21:29 | henry | Resolution | open => fixed |
