[MFN]

hello,


i'am using blockmesh for meshing and i dont know how the mesh can be graded on the top of my geometry ?

The expansion ratio enables the mesh to be graded only in the bottom with SimpleGrading.

hex (27 26 15 14 0 1 12 13) (100 180 1) sampleGrading (1 18 1) // block 0 outlet
hex (26 25 16 15 1 2 11 12) (800 180 1) sampleGrading (1 18 1) // block 1
hex (25 24 17 16 2 3 10 11) (10 180 1) sampleGrading (1 18 1) // block 2 inlet
hex (24 23 18 17 3 4 9 10) (10  180 1) sampleGrading (1 18 1) // block 3 inlet
hex (23 22 19 18 4 5 8 9) (800 180 1) sampleGrading (1 18 1) // block 4
hex (22 21 20 19 5 6 7 8) (100 180 1) sampleGrading (1 18 1) // block 5 outlet2

Anyone can help me please ?

[clapointe]

I came upon this thread yesterday -- it looks like what you're looking for has been coded previously : https://www.cfd-online.com/Forums/op...e-grading.html.

Otherwise, I've created half my domain and used mirrorMesh before to obtain the same result.

Caelan

[GerhardHolzinger]

With the current version of OpenFOAM, this is possible using standard blockMesh, see the user guide

Apart from the usual expansion ratio per direction, you can specify the grading for sections in a certain direction. The example below defines 2 sections with different grading in x-direction, and a uniform grading in the other directions.

// ( % dir, % No. of cells, expansion ratio )
hex ( 27 36 36 27 28 37 41 32 )   ( 96 1 11 )  grading (  ((0.05 0.3 50) (0.95 0.7 3.5)) 1 1  )

Each triple defines

• percentage of the edge's length
• percentage of the number of cells to use
• expansion ratio

Thus, the block definition above translates to a block, having 96 cells in x-direction, with a grading in x-direction of

• 30 % of the cells, on 5 % of the edge having an expansion ratio of 50
• 70 % of the cells, on 95 % of the edge having an expansion ratio of 3.5

The user guide says, that the percentages do not need to add up to 1 or 100. They simply specify the relative amount of the edge's length, or the number of cells.