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not sure how to approach meshing/continutiy

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Old   October 8, 2006, 02:36
Default not sure how to approach meshing/continutiy
  #1
Matthew R
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Hello all. I'm trying to mesh a tangentially fired boiler. I'm having trouble with the floating point error and i think it's because of my geometry. Fluent has identified 3 non positive volumes. I'm not sure if my approach to the mesh is correct. I will attempt to describe the geometry, anyone who would like it just ask. I have cubic burner ports arranged in the corners. Primary and secondary have slightly different angles. I have made a volume by intersecting these cubes at the correct angle into the main body. They protrude some depth into the body. The volume of the cubes that is outside of the main body has been removed. Hope that makes sense. The only mesh i can get to work is an unstructured tet/hybrid with hex core. Due to the nature of the geometry this gives me a poor mesh. Is this the right approach?

Secondly, i tried to have the non-complicated parts of my geometry filled with quad mesh, and the burner part the tet/hyrbrid. Strangely when i load the mesh in fluent there is no continuity between the the burner section and the others. Am i missing some step for the meshing...for continuity? I am quite an amateur at this, and just want to finish the damn thing since its a research project for uni!

Regards, Matt
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Old   October 8, 2006, 04:05
Default Re: not sure how to approach meshing/continutiy
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HSeldon
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Hey Matt! Itīs late here so my mind is at 20%, I couldnīt get well the picture of your problem, but Iīll tell you how I handle stranges geometries. First, I try to avoid asintotic edges joints (I mean, edges that finishes almost tangent between them). Then I try to avoid very sharps joints between faces (the same as the edges but with faces). In this case you can cut the end of the geometry by a planar face at the end, for example, if the trailing edge of an airfoil is too sharp Iīll cut that end by a small face, perpendicular to the mean chord of the airfoil. And finally if the geometry has smalls zones with complicated shapes I put a size function to control the growth rate to avoid bad/negative volume elements.

Hope this help!! Good luck with your project!
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Old   October 8, 2006, 04:07
Default Re: not sure how to approach meshing/continutiy
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Matthew R
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Hi HSeldon, thanks for the reply. Yeah, i do have almost tangential, and very small spots in the geometry. I think i'm going to simplify the geometry so the mesh is better. I'll look into size functions, thanks for the tip.

Regards, Matt
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