Does mesh refinement affect solver?

cltkgkdk · May 24, 2018, 09:10

I was trying to simulate fluid flow through a channel with different size of mesh.
I've tried 80k, 104k, 174k, 192.5k, and 260k no. of mesh. They all converges well, but when I try 240k mesh, error occurs during solver.
I'm sure that same boundary conditions were applied.

ghorrocks · May 24, 2018, 18:29

The numerical scheme in CFX is dissipative (just as for all solvers I know of). When you run a coarse mesh the numerical scheme adds dissipation which helps stabilise the convergence. As you refine the mesh the dissipation reduces and there comes a point when the stability is not adequate to converge. This is normal CFD solver behaviour.

If you find you need the fine mesh solution you will probably have to run transient to get it to converge.

May 24, 2018, 09:10	Does mesh refinement affect solver?	#1
cltkgkdk New Member Young Gun Lee Join Date: May 2018 Posts: 1 Rep Power: 0	I was trying to simulate fluid flow through a channel with different size of mesh. I've tried 80k, 104k, 174k, 192.5k, and 260k no. of mesh. They all converges well, but when I try 240k mesh, error occurs during solver. I'm sure that same boundary conditions were applied.

May 24, 2018, 18:29		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	The numerical scheme in CFX is dissipative (just as for all solvers I know of). When you run a coarse mesh the numerical scheme adds dissipation which helps stabilise the convergence. As you refine the mesh the dissipation reduces and there comes a point when the stability is not adequate to converge. This is normal CFD solver behaviour. If you find you need the fine mesh solution you will probably have to run transient to get it to converge. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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