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fully developed channel flow with kOmega, wrong results |
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April 19, 2016, 11:46 |
fully developed channel flow with kOmega, wrong results
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#1 |
New Member
Bob
Join Date: Nov 2014
Posts: 1
Rep Power: 0 |
Hi, everyone:
I am validating RANS models with channel flow using OpenFOAM-2.3.1, however, it went wrong with kOmega and kOmegaSST. The mesh is 2D, meanwhile, 1 cell in the streamwise direction. The bottom and upper boundaries are walls, which y+ =0.7. The left and right side are set to cyclic bc, and the frontAndBack is set to empty.(physical model, mesh and boundary conditions are shown in physical.jpg and mesh&bc.jpg) kOmega, kOmegaSST, and kEpsilon are used. kqRWallFunction, omegaWallFunction, nutkWallFunction, epsilonWallFunction are used for k, omega, nut, and epsilon. A pressure gradient term was added to simpleFoam, renaming as simpleFullyDevelopFoam, giving a pressure gradient to drive the fluid flow. Modification in UEqn.H Code:
//solve(UEqn() == -fvc::grad(p)); solve(UEqn() == -fvc::grad(p)-pGrad); Code:
//U = HbyA - rAU*fvc::grad(p); U = HbyA - rAU*fvc::grad(p) - rAU*pGrad; The results, however, is very wrong for kOmega. As can be seen from kOmega-res.jpg, there is a discontinuity of du/dy and dk/dy in the center of the channel. Also, kOmega converged to different results given different initial ux value. On the other hand, the kEpsilon do not exhibits such misbahavior (kEpsilon-res.jpg). Given all that shown, I am wondering if there is something wrong with kOmega and kOmegaSST model. Or, is there something wrong with the method that I added the pressure gradient? Is there a better way to achieve this? Hope to hear your suggestions. Best wishes, boshynova Last edited by boshynova; April 19, 2016 at 22:27. |
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April 20, 2016, 11:54 |
Should you try to use OpenFOAM-dev?
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#2 |
New Member
Xinze
Join Date: Mar 2009
Location: Shenyang, China
Posts: 15
Rep Power: 17 |
The turbulence library has been rewriten in the latest version, OpenFOAM-dev. you should try to use OpenFOAM-dev and check if it is a bug.
xz |
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boundary layer, fully developed, komega, openfoam 2.3.1 |
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