Do I need PRESTO!?, Body force weighted or ??

September 30, 2007, 00:38

Hi. I have a jet hitting a wall before leaving the outlet located at one end of the wall. Between the impingement point and the outlet, there are some swirls. Flow is incompressible and laminar.

In this case, should one apply a more elaborate pressure discretization scheme? I used the standard scheme and the outlet pressure is off by 20% compared to expt data. When I tried PRESTO!, solution diverges.

September 30, 2007, 19:38

To elaborate further, I also use the SIMPLEC. When in combination with PRESTO and with skewness correction of 1 or more, solution diverges. Without skewness correction, convergence can be achieved.

The question now is if skewness correction is necessary? Does it change the solution or does it affects only convergence speed?. The mesh is an unstructured hex.

If I use body force weighted, I can get a stable solution even with some skewness correction.

Can someone make sense out of these observations?

Bionico · August 31, 2012, 11:33

Hi everybody,
I'm modeling a heat source in a closed room. My mesh is quite dense: 4M tetra (around the source) and 4k Hexa (far from the source).
Can anybody tell me which discretization method for pressure is better? PRESTO! o BODY FORCE WEIGHTED? What are the differences between them?

Thanks in advance

Bionico · September 3, 2012, 08:38

I read something about the presence of corners: for this reason PRESTO! should be better. Can anyone confirm it?

wc34071209 · January 22, 2018, 08:32

Have you found the answers? I asked a similar question but have not received help yet.

September 30, 2007, 00:38	Do I need PRESTO!?, Body force weighted or ??	#1
jrg Guest Posts: n/a	Hi. I have a jet hitting a wall before leaving the outlet located at one end of the wall. Between the impingement point and the outlet, there are some swirls. Flow is incompressible and laminar. In this case, should one apply a more elaborate pressure discretization scheme? I used the standard scheme and the outlet pressure is off by 20% compared to expt data. When I tried PRESTO!, solution diverges.

September 30, 2007, 19:38	Re: Do I need PRESTO!?, Body force weighted or ??	#2
jrg Guest Posts: n/a	To elaborate further, I also use the SIMPLEC. When in combination with PRESTO and with skewness correction of 1 or more, solution diverges. Without skewness correction, convergence can be achieved. The question now is if skewness correction is necessary? Does it change the solution or does it affects only convergence speed?. The mesh is an unstructured hex. If I use body force weighted, I can get a stable solution even with some skewness correction. Can someone make sense out of these observations?

August 31, 2012, 11:33	PRESTO! or BFW ??	#3
Bionico Senior Member Flavio Join Date: Sep 2011 Location: Brescia, Italy Posts: 181 Rep Power: 16	Hi everybody, I'm modeling a heat source in a closed room. My mesh is quite dense: 4M tetra (around the source) and 4k Hexa (far from the source). Can anybody tell me which discretization method for pressure is better? PRESTO! o BODY FORCE WEIGHTED? What are the differences between them? Thanks in advance __________________ Bionico Last edited by Bionico; September 3, 2012 at 08:36.

September 3, 2012, 08:38		#4
Bionico Senior Member Flavio Join Date: Sep 2011 Location: Brescia, Italy Posts: 181 Rep Power: 16	I read something about the presence of corners: for this reason PRESTO! should be better. Can anyone confirm it? __________________ Bionico

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wc34071209 Senior Member Yuehan Join Date: Nov 2012 Posts: 142 Rep Power: 14	Have you found the answers? I asked a similar question but have not received help yet.