[zxw2006063]

Hi all,

I used the similar method as this video(https://www.youtube.com/watch?v=T1pVFCzrmGI) in pyformex(www.pyFormex.org) to generate the hexahedral elements for my vascular cfd in abaqus. The meshes were very well(very good 8 nodes 3d bricks). Then I exported the meshes to a .inp file with the nodes and elements information. In the .inp file, I set the element type as FC3D8 manually. After that I can import the .inp file in Abaqus/CAE with file-->import-->model. Then I got the orphan mesh in Abaqus/CAE. Everything goes well at this point. But when I use the mesh verify in abaqus/cae to check the meshes. It shows 100% elements with analysis errors.

I tried to create a job with these meshes and run it. But there was one error popping out, saying "Quadrature Errors in Pressure Poisson Equation - Element(s) severely distorted. Possible diagnostics are: (A) Check the quality of the elements in the mesh to see if they confirm to the element type specified. It is possible that certain elements are interpenetrating or have become degenerate during the mesh generation. "

I doubt the meshes generated from Pyformex are not compatible with the FC3D8 element type. However, the elements I can see from pyformex are quite well(very nice 8 nodes brick). And the group who developed the pyformex also used abaqus/cfd to do their simulation based on the meshes generated from pyformex.

I really don't know the reason. If anybody can give me some clues on this issue, I will be very grateful.

PS. I attached the .inp file and the pictures of the meshes. (https://www.dropbox.com/sh/hkgxbk3n5...oeVBo9bUa?dl=0)


Cheers
Charlie.

[zxw2006063]

I got this problem solved. It's because of the negative volume of the mesh. After reversing the meshes, everything goes well.

[danny261083]

Originally Posted by zxw2006063

I got this problem solved. It's because of the negative volume of the mesh. After reversing the meshes, everything goes well.

Hello Charlie,

I had a quick question regarding the implementation of the Bifmesh plugin in pyformex 0.9.1. I was unable to get the centerlines to work and the bifurcation geometry to slice correctly as indicated in your post. I followed the steps in the video tutorial but was not able to get it to work correctly. I was not sure whether the plugin works only for planar geometries. For some reason the bifmesh tutorial file ran without any errors. I was also wondering whether you could give me some tips on how to export the resulting mesh to either Abaqus or ANSYS Fluent.

Thanks

[zxw2006063]

Hi,

The original Bifmesh plugin indeed could not work well with non-planar geometry and you have to adapt the code by yourself in that case. Besides, the plugin only works with the geometry with one birfurcation. It means if your geometry does not have bifurcation or more than one bifurcation, it will not work at all.

By the way, if you want to adapt the code for your application, you first have to understand the python code the author wrote.

Hope this helps.


Charlie.