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Salome 3.2.1: Meshing the OpenCascade rim brep file

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  • Salome 3.2.1: Meshing the OpenCascade rim brep file

    Posted by JMB at September 24. 2006
    Hello all,

    I am trying to mesh a BREP file from the OpenCascade website.  The one I am attempting is "http://www.opencascade.org/ex/att/58_rim.brep.gz"  found at: "http://www.opencascade.org/showroom/shapegallery/gal5/"

    Some others I have tried from the same website, seem to work fine.  It appears that the more complex ones are failing.  All my attempts have been unsuccessful.  I am begining to think that the flaws are in Salome 3.2.1 because any attempts have resulted in "Failed to mesh" or it ties up my PC for 3-4 hours resulting in my having to abort the program.

    Could somebody assist please?  I would very much appreciate someone trying it and showing me what I am doing wrong.

    Thanks
    JMB


    • Re: Salome 3.2.1: Meshing the OpenCascade rim brep file

      Posted by Joël Cugnoni at September 24. 2006
      Hi,

      usually when Salome's tetra mesher runs forever, it is due to the iterative mesh optimization of the netgen algorithm.
      In order to have some feedback of the activity of the meshing plugins, you can try to run Salome from a console with:
      . /opt/salome/env_product.sh
      /opt/salome/KERNEL_XYZ/bin/salome/runSalome

      You will see the progress of the meshing algorithms. This could give you an hint on what's going on.

      Moreover, in most cases, a Mesh failed error comes when not all the surfaces have been meshed before a call to the tetrahedral mesher. So in general, it is a good approach to first try to mesh in 1D, then in 1D-2D and finally in 1D-2D-3D.
      After each mesh computation, try to update the mesh and check which surface or edge mesh fails.
      Some possible causes for mesh failed:
      1) 1D hypothesis not suitable for the geometry: average length or size of elements too large for the shortest edges for example.
      2) surface curvatures or aspect ratio (very long & narrow surface) creating errors in the meshing algorithm
      3) bad topology: free edges, open holes in surfaces.

      In general, too mesh complex geometries, the best option is to decompose the hypotheses:
      1) assign a general 1D hypothesis on the whole geometry
      2) create local 1D hypothesis for regions requiring finer meshes
      3) create 2D / 3D local hypothesis on each region with optimized parameters for each region
      This procedure is especially usefull when you have large volumes with small details in specific regions, which can make a global hypothesis to fail.

      Good luck...
    • Re: Salome 3.2.1: Meshing the OpenCascade rim brep file

      Posted by ashu106 at April 05. 2008
      JMB wrote:
      Hello all,

      I am trying to mesh a BREP file from the OpenCascade website.  The one I am attempting is "http://www.opencascade.org/ex/att/58_rim.brep.gz"  found at: "http://www.opencascade.org/showroom/shapegallery/gal5/"

      Some others I have tried from the same website, seem to work fine.  It appears that the more complex ones are failing.  All my attempts have been unsuccessful.  I am begining to think that the flaws are in Salome 3.2.1 because any attempts have resulted in "Failed to mesh" or it ties up my PC for 3-4 hours resulting in my having to abort the program.

      Could somebody assist please?  I would very much appreciate someone trying it and showing me what I am doing wrong.

      Thanks
      JMB



      hi ia trying to mesh but i can't do please provide me some help
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