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Old   January 9, 2007, 14:34
Default How to correct negative volume
  #1
aero
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Hi, I am doing Hexahedral Meshing (using block method).

but i am getting negative volume near one of the surface.

please help me how to correct it.

Thanks & regards aero
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Old   January 9, 2007, 17:54
Default Re: How to correct negative volume
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Joe
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Convert to unstruc mesh then run the quality checker it will offer to automatically fix the problem.
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Old   January 12, 2007, 00:31
Default Re: How to correct negative volume
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Luke
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You have to check your blocking and the distribution of nodes along the edges near the negative volume elements.

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Old   January 16, 2007, 07:19
Default Re: How to correct negative volume
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aero
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Hi,

Thanks for responses given. I have worked on improving quality of Tetra Mesh but this is my first problem in which i have to improve the Hexa Mesh Quality.

can you give some details on how to improve the Hex-Mesh Quality after converting into unstructured Mesh.

Thanks & Regards aero
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Old   January 16, 2007, 07:24
Default Re: How to correct negative volume
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Luke
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The important quality parameter to check for Hex-Mesh is Determinant 3X3X3. It should be >= 0.4 To improve the quality of a hex-mesh you should first check the jump of element size between adjacent edges. The jump should not be more than 1 to 1.5 times. The second thing to check is parallel edges should have the same distribution of elements and nodes. Sometimes you might have to join/split edges to get that. After plotting the determinant histogram you can see which are the cells falling below the value 0.4 and accordingly improve on those regions. Hope this helps.

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Old   January 19, 2007, 10:53
Default Re: How to correct negative volume
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aero
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Hi,

Thanks for response. It was very usefull.

In my model i want to increase Determinant 3X3X3 to a value of 0.7 but the problem is i am geting angle value less.

Please tell me what to do?

Thanks & regards aero
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