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October 1, 2009, 18:17 |
Possible bug in nutRoughWall
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#1 |
New Member
John O\'Sullivan
Join Date: Mar 2009
Location: Auckland, New Zealand
Posts: 7
Rep Power: 17 |
Hi all,
I think there may be a bug in the rough wall function. Its been discussed a little in the thread: http://www.cfd-online.com/Forums/ope...on-v1-6-a.html But basically nutw is set to 0 every time step. This means that scalar limitingNutw = max(nutw[faceI], nuw[faceI]); always returns limitingNutw = nuw[faceI]. This in turn means that nutw[faceI] = max ( min ( nuw[faceI] *(yPlus*kappa_/log(max(Edash*yPlus, 1+1e-4)) - 1), 2*limitingNutw ), 0.5*limitingNutw ); always returns nutw[faceI] = 2*limitingNutw As a result the simulation is subjected to a Ks much less than specified. In the test case attached the velocity should end up close to: u = u_star/kappa*log((z+z0)/z0) where in this case u_star = 0.625137, kappa = 0.4 and z0 = 0.01. I've fixed the problem buy adding the following lines which evaluate the limitingNutw using the values nut in the cell next to the wall. ... const tmp<volScalarField> toldnut = rasModel.nut(); const volScalarField& oldnut = toldnut(); ... ... scalar limitingNutw = max(oldnut[faceCellI], nuw[faceI]); ... Thanks! John Last edited by jposunz; October 1, 2009 at 18:40. |
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October 2, 2009, 02:56 |
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#2 |
Senior Member
Join Date: Mar 2009
Posts: 854
Rep Power: 22 |
Yes, we fixed this a couple of days ago and are testing the fix at the moment and will push it into 1.6.x shortly.
H |
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