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-   -   Mesh generator for very complex geometries (http://www.cfd-online.com/Forums/openfoam-meshing/61628-mesh-generator-very-complex-geometries.html)

hsieh November 21, 2007 00:51

Hi, I am looking for a mesh
 
Hi,

I am looking for a mesh generator capable of meshing very complex geometries. This will be for conjugate heat transfer. I need to mesh the solid parts and the fluid domain. Ideally, the nodes on the solid/fluid common faces should match. In additional, I have thin wall parts inside the domain, such as heat sink.

I have looked into cartesian grid mesher, but, at least 2 cells is needed across the thin wall. This will generate more than 10 million cells even when coarsening is performed away from the thin wall areas.

Can someone here suggest a mesh generator for very complex geometries with thin walls?

Thanks!

Pei

egp November 21, 2007 09:13

Pei, I would recommend Harp
 
Pei,

I would recommend Harpoon.

We've recently used it for the canine olfactory system. It is the most complex geometry I've every worked with, and has many complex thin walls. If you are interested, you can see it in last months Anatomical Record:

Craven BA, Neuberger T, Paterson EG, Webb AG, Josephson EM, Morrison EE, Settles GS, "Reconstruction and morphometric analysis of the nasal airway of the dog (Canis familiaris) and implications regarding olfactory airflow," Anatomical Record, 2007 Nov;290(11):1325-40.

We've built grids of 100,000,000 cells, and it is nearly automatic. It would be impossible to build these kind of grids with our other commercial meshers (Gridgen, ICEM-CFD).

Harpoon does export directly to OpenFOAM, however, for this project we've not used OpenFOAM.

In my opinion, Harpoon is a major enabler for this type of uber-crazy geometry.

Enjoy.

hsieh November 21, 2007 14:53

Hi, Eric, Thanks for the re
 
Hi, Eric,

Thanks for the reply!

I did try out Harpoon about 1 - 2 years ago, when they just came out with direct OpenFOAM export. I got quite a few problem at that time. One of the major issue I have was getting boundary face information. Because Harpoon uses stl, the boundary faces in CAD does not carry into harpoon. I need to split the cells to get boundary faces, but, it is not clean if I have curved/complex boundary faces.

Maybe I will ask the Harpoon guy to see if I can try out their latest version to see if this has been improved.

Pei

philippose November 21, 2007 15:51

Hello Pei, Good Evening!
 
Hello Pei,

Good Evening!

I tried out Harpoon version 2.4b (and 2.4c) around the end of 2006 beginning 2007, exactly because of the direct export to OpenFOAM capabilities.

Well.... Lets say..... The mesher is great, but as far as version 2.4c, it was definitely not ready for use by an OpenFOAM user.

For the two months that I tested Harpoon, I was in very close contact with Richard Bardwell via mail, to try and sort out the problems I faced...

In the end, it turned out, that the OpenFOAM export module in Harpoon was buggy, and I was told that there would be no motivation to improve the system, unless I decided to buy the software.

The decision of Sharc was that the demand for export into OpenFOAM format was not big enough to warrant a bug-fix.

Funnily, I also had problems with exporting into Fluent format, and that turned out to be a bug in the way surfaces were handled in Harpoon.

If I remember right... this problem was partly solved by following a specific sequence in Harpoon.

I also spoke to Sharc regarding the fact that Harpoon uses only STL for CAD imports, and I was told that the many years of experience Sharc has in the field has shown that STL is the most reliable format for importing CAD geometry for meshing..... though my experiences dont quite seem to align with that :-)!

Hmmmm.... I must say, that I was impressed with the meshing capabilities of the software, but was disappointed by the responses of Sharc, and the lack of motivation they showed in fixing problems..... in addition to their extremely commercial outlook.

Just as a disclaimer..... this is purely my experience with Harpoon and Sharc.... maybe things have changed since then!

Regards,

Philippose


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