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Problem incompressible Navier Stokes, using Flow in porous media (Brinkman Equation)
Posted 2010年6月25日 GMT-4 04:37 12 Replies
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I have a problem when a use the incompressible Navier Stokes with the activation of Flow in porous media (Brinkman Equation).
I get the next error:
Error:
Failed to find consistent initial values.
Matrix_has_zero_on_diagonal
What can I do?, I have tried everithing but nothing happen.
Regards
Pablo
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This is because of the solver, as the first guess. Switch to a Direct solver if possible to see if the problem is the solver or you have missed some physics. Also, since you enabled another physic, your stiffness matrix changes character and without fine tuning of pre-conditioners for iterative solvers (venka) it will give that error. I'm sure more experienced people can give your more detailed answer.
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What you mean with "Direct solver"? Is a option or something in the program?
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Thank a lot i didn't know this part.
I will try with this now and I will tell you the results
regards
Pablo
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now is running with the "Flow in porous media", thanks a lot for your help
Other question: There are a lot of different between the direct solve and the iteration solve? or is a goos solution too?
regards
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I would like to know what solver and what preconditionner that you used for your problem.
Regard
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I was using BigStab, but was not working, after i have change to PARDISO and is work.
But i have also the problem that when i try to mix with the Convection and diffusion equation (using the ouput of the navir stokes u,v,w ) only work with small values of the Initial Velocity in the Navier and this value is like 10000 time more small that the real value that i nedd.
What you mean with precondition. which values you need?
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we have preconditioner when we use indirects solvers like GMRES or FGMRES
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You have some ideo why is not working with big values in the Initial Velocity and only for small values?
regards
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merci
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