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- - **[Variation of the solution as the time step varies. RANS/Channel/Moser]**
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[Variation of the solution as the time step varies. RANS/Channel/Moser]Dear Foamers,
While testing the differents two equations eddy viscosity models with pisoFoam (modified) on a channel I experienced difficulties.With the k-w models, the converged mean profile and turbulent kinetic energy are time steps dependent. According to this, I would expect better results as I reduce the time step, or it is the reverse. As the time step is reduced the wall shear stress decreases and therefore the pressure drop I apply (to maintain a constant mass flux over my stream-wise periodic length). Result is that the Re_tau is way to low... Target Re_tau is 395 as in Moser simulations.http://img842.imageshack.us/img842/9412/plota.th.png The corresponding tau_wall and Re_tau is given in the table below (as a function of the time step): http://img573.imageshack.us/img573/5...donline.th.png Uploaded with ImageShack.us Does anyone experienced such results with the k-w and k-w SST models? My mesh is refined in the near wall region and I am using omegaWallfunction to provide proper boundary conditions to omega. PS: I am not observing the same behavior with "resolved" (without wallFunctions) LaunderSharmaLowKE. I therefore suspect the trouble from the boundary condition of omega or the numerics... I'm using OpenFoam 1.6.x |

any insight? :) I am really confused now...
Is it a good idea to increase to bulk velocity in order to obtain the right wall shear stress? I guess not.... |

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