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-   -   [snappyHexMesh] Is the changing on size of baground mesh of blockMesh; effect on the SHM result? (https://www.cfd-online.com/Forums/openfoam-meshing/124764-changing-size-baground-mesh-blockmesh-effect-shm-result.html)

s.m October 12, 2013 09:57

Is the changing on size of baground mesh of blockMesh; effect on the SHM result?
 
Hi,
i am simulating the flow over an airfoil, i use snappyHexMesh for meshing the domain around airfoil.
As we know in the first step is to produce a rectangular domain with blockMesh as background mesh of SHM

1. For the first snappyHexMesh run, i creat this backgraound mesh
convertToMeters 1;

vertices
(
(-1.2 -2.2 0.05)
( 5 -2.2 0.05)
( 5 2.2 0.05)
(-1.2 2.2 0.05)
(-1.2 -2.2 0.15)
( 5 -2.2 0.15)
( 5 2.2 0.15)
(-1.2 2.2 0.15)
);

blocks
(
hex (0 1 2 3 4 5 6 7) (182 176 1) simpleGrading (1 1 1) //(30*6.2 40*4.4 1)
);


2. For the second run of SHM, i change the size of the domain from 5 to 10 in +x axis and also the number of the subdivisions in this direction from 182 to 336:
convertToMeters 1;

vertices
(
(-1.2 -2.2 0.05)
( 10 -2.2 0.05)
( 10 2.2 0.05)
(-1.2 2.2 0.05)
(-1.2 -2.2 0.15)
( 10 -2.2 0.15)
( 10 2.2 0.15)
(-1.2 2.2 0.15)
);

blocks
(
hex (0 1 2 3 4 5 6 7) (336 176 1) simpleGrading (1 1 1) //(30*11.2 40*4.4 1)
);

As you see, i change the size of the domain over th +x axis and the instructions on this direction with eachother :
"(-1.2 to 5) --> (-1.2 to 10) & (30*6.2=182) --->( 30*11.2=336)

Now my question is:
Are thease two mesh the same as eachother?

all of the setting are the same for thease two mesh, only the size of domain for the first mesh over +x axis is till 5 and for the other one is till 10 in +x direction.
as you see the size of the cells that are filled the bacground domain mesh, are (1/30 * 1/40) for two mesh.
and all the settings for snappyHexMeshDict are also the same.

please clarify this question for me, if you can
Thank you very much.:)


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