convergence problem
Hi there.
I am quite new into modelling but i got a convergence problem as follow DICPCG ask a many iteration. How to make it less? is improving the grid resolution or lowering the grid resolution could help? or a better approximation of k and epsilon is the solution? And all link about it are welcome Quote:
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hello...
I think the problem is because of the mesh resolution. I just want to know which type of grid have you used? Is it Unstructured?
If it's unstructured then it's usual you will observe the error, check out with structured if you get the same. :o -------- |
Check the mesh quality with checkMesh - you could have problems with skewed cells, etc. If you get good results from checkMesh, you are ready to start working on the solution. First, instead of refining the mesh, I would do the opposite. A coarse mesh lets you get the 'outline' of the solution quickly, and shows if your setup is valid. If you can get a coarse mesh solution to converge, then start refining your mesh.
Good luck, Alan |
Hi thanks for your answers.
What do you mean by unstructured? My grid got a sinus form... and my my grid resolution is around 0.01m and dT = 0.001; This is the answer of the checkMesh Quote:
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In your checkMesh, I see an outlet but no inlet, which will cause problems with the continuity equation (conservation of mass). Most of your setup is like the cavity tutorial, except for the outlet. Can you describe what you are trying to model? You will certainly need some kind of inlet if you have an outlet.
Alan |
Can you please upload your case file??
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I don't specify the inlet, i just want a uniform wind field at the boundaries
Moving wall +-------------------------------------------------------------------+ | .................................................. ........................................ | |................................................. .......................................... | Moving Wall .................................................. .....................outlet | .................................................. .........................................| | .................................................. .........................................| _.-._.-._.-._.-._.-._.-._.-._.-._-._.-._.-._.-._.-._.-._.-._.-._.| The ground is a sin function, and i want to view the turbulence around it. [QUOTEFoamFile { version 2.0; format ascii; class volVectorField; object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { movingWall { type fixedValue; value uniform (1 0 0); } fixedWalls { type fixedValue; value uniform (0 0 0); } outlet { type zeroGradient; } frontAndBack { type empty; } } // ************************************************** *********************** // ][/QUOTE] If you need more just ask Thank you for your interest anyway |
I had try a lower grid scale as around 0.05m and there is a good convergence
... How to explain it? :confused: my first guess was more the grid scale is small more the convergence is fast ... |
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