problem mesh scale

jc_muaddib · May 28, 2010, 09:16

Hi!
I'm using cfx-mesh for the first time and I'm doing a hvac simulation of a big workshop. And I have some problems to get a mesh as I would like. Indeed there are quite a lot of devices which complicate the design; and when I have tried to mesh, one time I got this error: It's continually adding and removing the same element (I think it's because the mesh scale it's to big for a part of my geometry).
But when I have refined the mesh until the error disappeared, the generation time for meshing became to long. I try to use proximity only to refine the part causing the error but I was only able to use it for the entire volume.
So finally my questions are:
How can I refine only a part of a volume (as in icem)?
Should I simplify my geometry? (but in this case the simulation would be affected)

I'm looking for your hints!

Jordi · May 28, 2010, 12:27

Sometimes small details can be simplified... If your domain is big as you say I would suggest bodies and shapes be "smoothed out". This easies the mesher work, your waiting time and your computer load...
Anyways, simulations are approximations to real behaviour, and you always can make it more complex.
For fluids it's important to set up inflations at the walls, because fluid speed is zero.
You can partition your fluid domain into as many volumes as needed and set different size limits for each domain

jc_muaddib · May 31, 2010, 10:38

Ok,

I'll try to simplify the geometry and refine the mesh in some critical parts.

Thanks for the explanations!

May 28, 2010, 09:16	problem mesh scale	#1
jc_muaddib New Member anonymous Join Date: Mar 2010 Posts: 8 Rep Power: 16	Hi! I'm using cfx-mesh for the first time and I'm doing a hvac simulation of a big workshop. And I have some problems to get a mesh as I would like. Indeed there are quite a lot of devices which complicate the design; and when I have tried to mesh, one time I got this error: It's continually adding and removing the same element (I think it's because the mesh scale it's to big for a part of my geometry). But when I have refined the mesh until the error disappeared, the generation time for meshing became to long. I try to use proximity only to refine the part causing the error but I was only able to use it for the entire volume. So finally my questions are: How can I refine only a part of a volume (as in icem)? Should I simplify my geometry? (but in this case the simulation would be affected) I'm looking for your hints!

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May 28, 2010, 12:27		#2
Jordi New Member Jordi Join Date: May 2010 Posts: 26 Rep Power: 15	Sometimes small details can be simplified... If your domain is big as you say I would suggest bodies and shapes be "smoothed out". This easies the mesher work, your waiting time and your computer load... Anyways, simulations are approximations to real behaviour, and you always can make it more complex. For fluids it's important to set up inflations at the walls, because fluid speed is zero. You can partition your fluid domain into as many volumes as needed and set different size limits for each domain

May 31, 2010, 10:38		#3
jc_muaddib New Member anonymous Join Date: Mar 2010 Posts: 8 Rep Power: 16	Ok, I'll try to simplify the geometry and refine the mesh in some critical parts. Thanks for the explanations!