edgeGrading
 

Hi everyone,

I'm a beginner with openFOAM.

I have some problem to understand edgeGrading...I understood that I have to define the expansion ratio for each edge of the hexahedron. They are grouped along the three directions, so the first 4 edges are all the edges along X1 and so on for X2 and X3. The thing I can't understand is to which edge corresponds each number in the parenthesis :confused:. How are they ordered?

Thanks!

Hi,

I would think they are ordered from 0 to 11 within the parenthesis with edge 0 etc. being defined as described here:

http://cfd.direct/openfoam/user-guide/blockMesh/

No?

Cheers,
Antimony

Hi Antimony!

Thank you for your reply! You're right. In my case, I had this error:

Inconsistent number of faces between block pair 2 and 7

and I thought it was due to grading, but it wasn't. The problem was the way I had defined the blocks: I didn't take care of the order of vertices in the hex(...), but now I understood that this order defines axis X1, X2 and X3 for each block.

Is it correct?

Hi,

Generally if you have inconsistent number of faces, it usually means that the number of cells between the different blocks has a mismatch. Unless you are duplicating vertices (and therefore duplicating edges), the common edge shared by two blocks will need to have the same number of divisions.

And yes, the ordering of the vertices determines the axes and consequently, whether or not your cells are "proper". In case your order of vertices is wrong, you will end up with cells with negative volumes which blockMesh will report during its run.

Hope this helps.

Cheers,
Antimony