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Joel July 23, 2007 15:13

Concave meshing in Gridgen
I am trying to extrude a block from domains in a concave corner. On the horizontal is an unstructured domain, and on the vertical is a structured domain. I am running a type "normal" extrusion. The gridlines try to extrude normal to their original surface, which mostly works fine. But as the extrusion progresses, the bottom row of cells of the structured domain remains the same width but becomes increasingly shorter as the unstructured domain is extruded up towards it. Eventually the gridlines of the bottom row cross themselves and the extrusion stops. I have tried increasing the stretch factor in the corner to its maximum but that doesn't work.

Is there any way to run the extrusion so the gridlines (of both structured and unstructured domains) will not extrude normal to their original orientation? Or is there another way to run the extrusion?

Thanks in advance

John Chawner July 28, 2007 15:07

Re: Concave meshing in Gridgen
Hello Joel,

There are a number of controls you can set for normal extrusion that will effect how the angle of the grid lines' trajectories are computed. They all involve smoothing various geometric parameters over the corner between your two surfaces. Look at the 1D and 2D smoothing attributes. If you need some help figuring out which ones to use or how to set the coefficients, contact our Tech Support at

Another technique you might try is the anisotropic tetrahedral extrusion in Gridgen Version 15.10. This method requires triangles for the surface grids, but it's much more flexible when it comes to handling sharp, concave corners.

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