# omega wilcox definition

 Register Blogs Members List Search Today's Posts Mark Forums Read

 May 9, 2016, 11:37 omega wilcox definition #1 Senior Member   Join Date: Mar 2016 Posts: 133 Rep Power: 2 I'm using k-omega SST model in Low-Re mode so without wall functions. I set omega with fixedValue calculated with wilcox's formula: omega = 6*nu/(0.075*y^2) in which y should be the first cell center nearest to wall. How i can calcaulate this? Is there an utility for this?

 May 11, 2016, 17:13 #2 New Member   Clara Join Date: Sep 2010 Location: Bruxelles Posts: 15 Rep Power: 8 Dear giammy92, What do you need to calculate? y or omega? or you want to calculate omega within the code directly? Cheers!

 May 11, 2016, 18:37 #3 Senior Member   Join Date: Mar 2016 Posts: 133 Rep Power: 2 Hi risku9, I want calculate omega with wilcox formula at wall because I think that is more accurated compared to omegaWallFunction. I need to know y in formula that should be the first cell center right? Is there an utility to calculate it?

 May 11, 2016, 18:48 #4 New Member   Clara Join Date: Sep 2010 Location: Bruxelles Posts: 15 Rep Power: 8 Hey! If what you want to get is y, I think you can find it in the wall function definition of omegaWallfunction: src/turbulenceModels/incompressible/RAS/derivedFvPatchFields/wallFunctions/omegaWallFunctions/omegaWallFunctions You can find this piece of code: const scalarField& y = turbulence.y()[patchI]; Which I believe refers to the nearWall distance, as if you look into the C++ documentation of OpenFOAM: http://openfoam.github.io/Documentat...ml/a01744.html Looking for turbulenceModel::y() and clicking on it you will reach: http://openfoam.github.io/Documentat...ce.html#l00157 where it explains: //- Return the near wall distances 158 const nearWallDist& y() const 159 { 160 return y_; 161 } So I think if you use that turbulence.y() as in the omegaWallFunction now, you should be able to get to do what you would like! I hope this helps! =)

 May 12, 2016, 07:11 #5 Senior Member   Join Date: Mar 2016 Posts: 133 Rep Power: 2 Sorry i haven't understood well what i have to do to obtain near wall distance.

 May 12, 2016, 12:27 #6 New Member   Clara Join Date: Sep 2010 Location: Bruxelles Posts: 15 Rep Power: 8 Hey, So I think you would just need to create a new wall function, in which you set that omega to the value you want. I was checking the original OmegaWallFunction in the code in the folder of installation of openfoam: OpenFOAM/src/turbulenceModels/incompressible/RAS/derivedFvPatchFields/wallFunctions/omegaWallFunctions/ And it is almost already what you are looking for as beta1_ = 0.075, you would just need to comment the omegaLog component. If look in line 234 from omegaWallFunction.C file: // Set omega and G forAll(nutw, faceI) { label cellI = patch.faceCells()[faceI]; scalar w = cornerWeights[faceI]; scalar omegaVis = 6.0*nuw[faceI]/(beta1_*sqr(y[faceI])); scalar omegaLog = sqrt(k[cellI])/(Cmu25*kappa_*y[faceI]); omega[cellI] += w*sqrt(sqr(omegaVis) + sqr(omegaLog)); G[cellI] += w *(nutw[faceI] + nuw[faceI]) *magGradUw[faceI] *Cmu25*sqrt(k[cellI]) /(kappa_*y[faceI]); }

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post lpz_michele OpenFOAM Running, Solving & CFD 53 October 19, 2015 02:50 Max1234 OpenFOAM Running, Solving & CFD 15 July 2, 2015 06:38 Scabbard OpenFOAM Running, Solving & CFD 2 September 30, 2014 13:06 asaijo OpenFOAM Installation 9 April 6, 2011 12:21 jpo FLUENT 4 April 7, 2009 15:06

All times are GMT -4. The time now is 05:33.