Asking size function...
 

Hi Everybody,,
In meshing banki water turbin. i have problem in controlling pattern of meshing. I've read that it can be solved by size function. I've tried to apply the step from "gambit tip & trick" but it can't work. Can you help me out my problem?? do you have reference??
thanks:D
teguhtf

check User Guide, size functions are well described

i have problems with the size function too. i dont think they are that well explained in the online help for someone who is unexperienced.

i have a simple airfoil and an outerflowfield. i want to create a mesh which is fine near the airfoil and gets bigger at the flowfield borders. what do i need to set as source and attachment?

and what values should i use for start size, growth and size limit.

thanks

thanks max. I have understood it. But my geometry is complex enough hence i cannot apply size function easily. I have tried to make inflated boundary but it cannot work so i just mesh in high density of mesh around the blade.

Hi
check this out!! www.anova.com.tr/dosyalar/destek/gambittips.pdf
Maybe it can help you out your problem.
By the way, for smooth mesh near wall, why you don't use boundary layer mesh?? i think its great to get drag value!!
teguhtf

for complex geometries, you need to split your domain into several smaller subdomains.
You will have more control on your mesh

thank you for your help.

the thing i am doing is for a schoolproject. we are told to find the cl of an airfoil. we need to create a boundary layer around the airfoil and then us tri/pave for the mesh.

i attached some pictures so that you can see what i mean. the outerflowfield is a face and the innerflowfield is a face too.

if i now use the size function and pick the edges of the airfoil as source and the innerflowfield face as attachment it doesnt quite seem to work. i dont get a mesh at all. maybe someone of you knows some good values i need to enter?

outerflowfield:

http://i45.tinypic.com/ixf8rn.jpg

innerflowfield:

http://i45.tinypic.com/210hmow.jpg

we can't see the pictures

I can see...
 

I can see the pics... Maybe it is because I wear these cool shades :cool:

i dont know why max cant see the pictures. maybe you have an adblocker which blocks tinypic?

anyways, i figured out how to use the size function now thanks again for your help.
the next problem i have is that i have a negative volume (i am in 2d though, dont know whats happening) somewhere in my mesh when i read it into fluent.

You can check the worst element of your mesh and repair it. I think that is the troublemaker of your case.
teguhtf

Thank's max, I'll try that!!!:D
teguhtf

In Gambit go to examine mesh.
Choose Volume, and set the max value to 0.
It will show you all cells with negative volume

i think i have one element with a negative volume and 10 left handed elements. how can i find those?