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-   -   [GAMBIT] Not sure how to mesh this (http://www.cfd-online.com/Forums/ansys-meshing/63577-not-sure-how-mesh.html)

 mbeals April 13, 2009 13:10

Not sure how to mesh this

I am attempting to simulate flow around an instrument that is to be mounted under the wing of an aircraft. Instead of attempting to describe it, here is a screen shot from gambit:

http://i39.tinypic.com/ftd4le.jpg

The model I'm working with is extended back a little by projecting the rear [hidden] face in the +x direction to simulate the body of the probe past the shroud. This probe will be typically flying around 30k feet (200 mb) and 225 m/s, and I need to be able to simulate it with a compressible regime.

I've managed to mesh and model a test run, but It's not to my liking and I'm not sure exactly how to proceed.

Currently the bulk of the surface of the probe is meshed at a 1mm interval at the front working back to a 5mm interval on the less complicated portions of the shroud and body. This is as course as I could go while maintaining skewness under 0.5. The probe, from tip to back of the housing is approx 500 mm long and the tips are (outside edge-edge) 200 mm wide. I currently have a domain that is 1100x1000x1000 mm along the same axis layout as in the image. That puts 550 mm of clear air in front of the probe, about 350 in the +/- y direction and nearly 450 in the +/- Z.

I can successfully mesh this volume using T-grid, which produces reasonable results when run in noncompressible mode. However, the mesh interval in the critical region I want to study (between the tips and out in front) becomes very coarse, very quickly and I'm not sure I'm achieving the particle calculation accuracies I need.

Is there a way to essentially mesh an interior part of the volume on a constant mesh spacing, then grow that out through the rest of the volume? I tried dividing the volume into two parts...with a cylindar surrounding the probe, meshed at a small interval, then growing the mesh in the outer domain using a boundary layer and the cooper scheme, but that interface between the two volumes is causing weird things to happen.

 -mAx- April 14, 2009 02:04

you can mesh everything with gambit (even complex geometries).
The problem occures when you try getting full hexa-mesh
Regarding your issue, try with tet-hexcore and apply size-function

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