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-   -   Size Functions in Gambit (http://www.cfd-online.com/Forums/fluent/32676-size-functions-gambit.html)

chanchala December 8, 2003 12:38

Size Functions in Gambit
 
Hi,

For a curved geometry, I wanted to use Curvature Size Function. You are asked to specify: Angle, Growth rate, Distance and Size limit. I understand what Growth rate is but Gambit help files are pretty vague about the others. If anyone's used size functions please explain how I can make sense of these. I've had a few trials trying to mesh using the curvature size function but can't see any difference really.

thanks, Chanchi

Rahul December 9, 2003 07:44

Re: Size Functions in Gambit
 
Hi you have written as if you are compleing to Support group of Fluent. Anyway I have used Size function many times and found very usefull specially if you have many opening in a area and also area is iregular. Many time we can not get mesh without size funtion or we have to split areas. Size functions are good for free meshing only. Using Curvature Size Function may times you may not much difference with change in angle as Gambit will try to give better mesh by adjsting it. Actually we use shape function to get better controlled over mesh.

Size limit is max size of cell in that zone (area or edge) I hope I clarified your doubts.

chanchala December 9, 2003 09:24

Re: Size Functions in Gambit
 
Hi Rahul,

Sorry if it sounded as if I was complaining, after a whole afternoon playing with size functions I think I felt disheartened.

Thanks for your help. I hope maybe you can help me a bit more. I have to mesh a cylindrical pipe with tetrahedral mesh (for various reasons). I got a big difference in results when I compared results from a hex mesh to tet mesh so I asked fluent support why this may be. They said I should make sure that I use the right size function for the tet mesh. I thought perhaps curvature was the best one. Does the fact that applying this gives me no difference mean that there is no improvement necessary?

thanks again, chanchi

Rahul December 9, 2003 09:50

Re: Size Functions in Gambit
 
Usually you should use bit finer mesh when you go for tet. If you are having simple goemetry then you need not to go for size function. Even if you for size function go for fixed one instead of curved size function as it seems your geomery is not having so much curved faces. Best way to compare hex and tet resuts is compare grid-independent results. Rahul


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