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-   -   recommended cell expansion ratio (http://www.cfd-online.com/Forums/openfoam/80797-recommended-cell-expansion-ratio.html)

guy_smiling October 6, 2010 15:24

recommended cell expansion ratio
 
Hi all,

I remember reading somewhere that the recommended cell expansion ratio was between 0.833 and 1.2 from adjacent cells, but I can't seem to find that reference anywhere now. Does anyone know if there is a recommended cell expansion ratio and if there's a good reason for it?

Thanks.

LarsPT October 12, 2010 13:15

Maybe I found something. If I use high expansion rates, i.e. high cell aspect ratios and run checkMesh -allGeometry -allTopology, I will get an error message because of small determinant of some cells. A cell determinant of 1 relates to a hexahedral cell whereas a small value relates to an illegal flattened cell. As far is I had a look at this problem the error occurs when the cell determinant is smaller than 1e-03. So one can maybe conclude to a maximal aspect ratio?

Lars


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