Setting 'lowest pressure' pMin in compressibleInterFoam

kjetil · December 2, 2009, 10:49

Dear foamers,

the only thing remaining in my university term project, is to get get my water-air simulation from solver interFoam to the compressibleInterFoam. I have searched for info on how to use the compressible solver, but nothing of any use exists. My main problem is that setting the pressure pMin to a fixed value, the internal pressure fluctuates constantly/periodically - and in turn so does the velocity field. Does anybody have any hints at all to what to set pMin to, to get a stable simulation going? And what is the purpose of this pMin in the first place?

Thank you.

Marta · April 21, 2010, 14:30

Hi! Do you know how to set the pMin parameter correctly depending on the case you are solving? How does it affect the solution exactly?

Thanks

Marta

kjetil · April 21, 2010, 18:00

Hi Marta
unfortunately I didn't get an answer to this - but you might try to set it to zero or something close to zero, as 10E-6 or around that.

So, I too wish that someone could elaborate on the use of this pMin.

flowman · April 21, 2010, 21:40

Hi Kjetil,

compressibleInterFoam uses an equation of state: rho=p*psi. For isothermal expansion psi=1/RT. The value of the minimum pressure, pmin, must be set to something greater than zero to ensure the equation of state returns a density greater than zero to the solver.

See this thread for more info on compressibleInterFoam.

What type of problem are you trying to solve? Are you sure this equation of state is appropriate?

December 2, 2009, 10:49	Setting 'lowest pressure' pMin in compressibleInterFoam	#1
kjetil Senior Member Join Date: Mar 2009 Location: Norway Posts: 138 Rep Power: 17	Dear foamers, the only thing remaining in my university term project, is to get get my water-air simulation from solver interFoam to the compressibleInterFoam. I have searched for info on how to use the compressible solver, but nothing of any use exists. My main problem is that setting the pressure pMin to a fixed value, the internal pressure fluctuates constantly/periodically - and in turn so does the velocity field. Does anybody have any hints at all to what to set pMin to, to get a stable simulation going? And what is the purpose of this pMin in the first place? Thank you.

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April 21, 2010, 14:30		#2
Marta Member Marta Lazzarin Join Date: Jun 2009 Location: Italy Posts: 71 Rep Power: 17	Hi! Do you know how to set the pMin parameter correctly depending on the case you are solving? How does it affect the solution exactly? Thanks Marta

April 21, 2010, 18:00		#3
kjetil Senior Member Join Date: Mar 2009 Location: Norway Posts: 138 Rep Power: 17	Hi Marta unfortunately I didn't get an answer to this - but you might try to set it to zero or something close to zero, as 10E-6 or around that. So, I too wish that someone could elaborate on the use of this pMin.

April 21, 2010, 21:40		#4
flowman New Member Aidan Join Date: Apr 2010 Posts: 18 Rep Power: 16	Hi Kjetil, compressibleInterFoam uses an equation of state: rho=p*psi. For isothermal expansion psi=1/RT. The value of the minimum pressure, pmin, must be set to something greater than zero to ensure the equation of state returns a density greater than zero to the solver. See this thread for more info on compressibleInterFoam. What type of problem are you trying to solve? Are you sure this equation of state is appropriate?