[blockMesh] I think my solution is distorted by my mesh

allanZHONG · October 14, 2021, 22:26

Hi,

I am simulating external flows around a simple building array using simpleFoam, and I am using a structured hexahedral mesh generated by blockMesh. I have to make the wall-adjacent mesh denser, and I am using the cell-to-cell expansion ratio of 1.1. When I am simulating using the coarser mesh (y+ > 30), the solution looks fine, and it does not show weird patterns. But, after I switched to the finer mesh (y+ = 7~9, same expansion ratio), I got weird patterns from my solution, and I think this has something to do with the mesh being too stretched, bu I cannot be sure as I've seen others getting perfect OK solutions with similar stretched meshes. Anyone who have seen this problem before? Maybe your words will help me get out of this difficult position.

The slice view of the x-y plane for my finer mesh is attached as below,

The same view for my solution is attached as below.

allanZHONG · October 14, 2021, 22:28

Seems like the way i inserted the images is wrong, so I am simply uploading them as attachments now

allanZHONG · October 19, 2021, 09:15

Having let the calculation to proceed for a while, I found that these weird patterns on the solution disappeared.

October 14, 2021, 22:26	I think my solution is distorted by my mesh	#1
allanZHONG New Member Allan ZHONG Join Date: May 2021 Posts: 3 Rep Power: 4	Hi, I am simulating external flows around a simple building array using simpleFoam, and I am using a structured hexahedral mesh generated by blockMesh. I have to make the wall-adjacent mesh denser, and I am using the cell-to-cell expansion ratio of 1.1. When I am simulating using the coarser mesh (y+ > 30), the solution looks fine, and it does not show weird patterns. But, after I switched to the finer mesh (y+ = 7~9, same expansion ratio), I got weird patterns from my solution, and I think this has something to do with the mesh being too stretched, bu I cannot be sure as I've seen others getting perfect OK solutions with similar stretched meshes. Anyone who have seen this problem before? Maybe your words will help me get out of this difficult position. The slice view of the x-y plane for my finer mesh is attached as below, The same view for my solution is attached as below.

October 19, 2021, 09:15	The weird solution is just due to unconverged calculation	#3
allanZHONG New Member Allan ZHONG Join Date: May 2021 Posts: 3 Rep Power: 4	Having let the calculation to proceed for a while, I found that these weird patterns on the solution disappeared. guin likes this.

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