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-   -   A DMZ for snappyHexMesh (http://www.cfd-online.com/Forums/openfoam-meshing-snappyhexmesh/107190-dmz-snappyhexmesh.html)

ConnClark September 19, 2012 20:19

A DMZ for snappyHexMesh
 
Hello,

I have been meshing with some large meshes (at least for my laptop) and have about 6GB of data swapped out before snappyHexMesh starts eliminated mesh cells that are in enclosed surfaces. Is there a way to designate a Don't Mesh Zone to tell sHM not to bother with refining or meshing in volume before it gets to the point of eliminating cells in an enclosed surface? (if not it would be a nice feature to save time meshing )


Thank You

Conn

SirWombat September 20, 2012 04:23

Here's an idea: you could use a "coarse" snappyHexMeshDict with a smaller surface than the original one. Then use your "fine" snappyHexMeshDict on that mesh. This will only work, if all of the "fine" surfaces is still inside a mesh region. Otherwise snappy won't snap at all.

SirWombat September 20, 2012 04:29

just tried it with my setup, 'cause I really like the idea of saving memory and time!!

for the coarse mesh (snappyHexMeshDict_coarse):
Code:

castellatedMesh true;
snap            false;
addLayers      false;

then turn all your surface refinements to "0" and delete all refinementRegions.

for the fine mesh (snappyHexMeshDict_fine):
just take you original snappyHexMeshDict.


I used the following script "fastermesh.sh"
Code:

#!/bin/sh
cp system/snappyHexMeshDict_coarse system/snappyHexMeshDict
blockMesh
snappyHexMesh -overwrite
cp system/snappyHexMeshDict_fine system/snappyHexMeshDict
snappyHexMesh -overwrite


Seems to work very well in my case.


Greetings,
Jan

ConnClark September 20, 2012 18:56

Thank You, That helped a lot!!

Conn

ConnClark September 21, 2012 12:58

Oops,

I spoke too soon. After looking at the simulation data something wasn't right. The Mercedes I was simulating has been turned into a rice-boy neo-cubist car. :rolleyes: The coefficient of lift is an impressive value of 1.4 . I don't think anybody has achieved that in auto design before. ;)

back to swapping to disk.


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