What are rhoMin and rhoMax in rhoPimpleFoam?

immortality · January 9, 2013, 13:31

in rhoPimpleFoam there are rhoMin and rhoMax what they mean?what are their coefficients?
thaaaaaaaaaaanks!

maHein · January 11, 2013, 18:30

The density in the solver rhoPimpleFoam is limited by the values "rhoMax" and "rhoMin" defined in fvSolutions.

immortality · January 12, 2013, 04:34

thanks.how should it be adjusted based on case?

immortality · January 15, 2013, 12:43

any idea about setting the rhoMin and rhoMax?
do we should a guess about minimum and maximum f rhos in the problem we solve?or its default should be used?
please give me a guide.
thanks alot.

mturcios777 · January 15, 2013, 13:36

These are values that you set based on your knowledge of the case you are simulating. It is up to you to ensure they are correct. If you look in the pEqn.H file you will see that is the operation done rho = max(rho,rhoMax) and the like.

immortality · January 16, 2013, 10:46

im not sure about max and min of rho exactly.can i set it by a factor of safety?then turn the results less exact or just each iteration takes more time?
Thanks.

mturcios777 · January 16, 2013, 13:55

No, all that happens is that after the p is solved for, rho is then limited by the max/min values. All cells where rho is > rhoMax are set to rhoMax, all cells where rho < rhoMin are set to rhoMin.

immortality · January 16, 2013, 18:10

excuse me.why it is intended?density is obtained from equation of state,isn't it?if thats true why rho is bounded?and if we acept that it doesn't seem an accurate way.could give me a bit guidance?

mturcios777 · January 16, 2013, 18:21

The bounding is there for your convenience; this is to bound the solution if you want. If you don't want rho to be bounded, just set rhoMin 0 and rhoMax to something absurdly high.

January 9, 2013, 13:31	What are rhoMin and rhoMax in rhoPimpleFoam?	#1
immortality Senior Member Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,208 Rep Power: 27	in rhoPimpleFoam there are rhoMin and rhoMax what they mean?what are their coefficients? thaaaaaaaaaaanks!

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January 11, 2013, 18:30		#2
maHein Member Join Date: Jun 2012 Posts: 76 Rep Power: 14	The density in the solver rhoPimpleFoam is limited by the values "rhoMax" and "rhoMin" defined in fvSolutions.

January 12, 2013, 04:34		#3
immortality Senior Member Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,208 Rep Power: 27	thanks.how should it be adjusted based on case?

January 15, 2013, 12:43		#4
immortality Senior Member Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,208 Rep Power: 27	any idea about setting the rhoMin and rhoMax? do we should a guess about minimum and maximum f rhos in the problem we solve?or its default should be used? please give me a guide. thanks alot.

January 15, 2013, 13:36		#5
mturcios777 Senior Member Marco A. Turcios Join Date: Mar 2009 Location: Vancouver, BC, Canada Posts: 740 Rep Power: 28	These are values that you set based on your knowledge of the case you are simulating. It is up to you to ensure they are correct. If you look in the pEqn.H file you will see that is the operation done rho = max(rho,rhoMax) and the like.

January 16, 2013, 10:46		#6
immortality Senior Member Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,208 Rep Power: 27	im not sure about max and min of rho exactly.can i set it by a factor of safety?then turn the results less exact or just each iteration takes more time? Thanks.

January 16, 2013, 13:55		#7
mturcios777 Senior Member Marco A. Turcios Join Date: Mar 2009 Location: Vancouver, BC, Canada Posts: 740 Rep Power: 28	No, all that happens is that after the p is solved for, rho is then limited by the max/min values. All cells where rho is > rhoMax are set to rhoMax, all cells where rho < rhoMin are set to rhoMin.

January 16, 2013, 18:10		#8
immortality Senior Member Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,208 Rep Power: 27	excuse me.why it is intended?density is obtained from equation of state,isn't it?if thats true why rho is bounded?and if we acept that it doesn't seem an accurate way.could give me a bit guidance?

January 16, 2013, 18:21		#9
mturcios777 Senior Member Marco A. Turcios Join Date: Mar 2009 Location: Vancouver, BC, Canada Posts: 740 Rep Power: 28	The bounding is there for your convenience; this is to bound the solution if you want. If you don't want rho to be bounded, just set rhoMin 0 and rhoMax to something absurdly high.