# compressibleInterFoam: specific gas constant of liquids

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 February 1, 2015, 11:24 compressibleInterFoam: specific gas constant of liquids #1 New Member   Join Date: Dec 2013 Posts: 3 Rep Power: 12 Hey, I am a new user on OpenFoam. I would like to run a compressible, multiphase (molten metal and air) case with compressibleInterFoam. I use “perfectFluid” for the molten metal and I have a question about the specific gas constant R. The significance of this value has already been discussed in the thread http://www.cfd-online.com/Forums/ope...ion-state.html . Why is the gas constant in the tutorials for water 3000? I don´t know whether the value was calculated or just selected. Regards, Niklas joshmccraney and cjacob like this.

 April 10, 2015, 06:12 #2 New Member   mohammed musthafa Join Date: Dec 2014 Location: India Posts: 5 Rep Power: 11 Dear Niklas Its easy to run that case, but the gas constant value given in tutorial is not correct. So kindly check all the values before you run your case. Regards musthafa

 May 17, 2016, 04:23 #3 Senior Member   Huynh Phong Thanh Join Date: Aug 2013 Location: Ho Chi Minh City Posts: 105 Rep Power: 12 Dear all, I computed the fluid constant R with perfect fluid state for water material that it is difference tutorial compressibleInterFoam OF 2.2.2 But in tutorial R equal to 3000 J/(kg K). Does any people explain me what R tutorial value is? Thank you so much, Thanh RaghavendraRohith and joshmccraney like this.

November 5, 2017, 17:59
#4
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M. C.
Join Date: May 2013
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Quote:
 I computed the fluid constant R with perfect fluid state for water material that it is difference tutorial compressibleInterFoam OF 2.2.2 R = \frac{8314.32}{Mole Weight}=\frac{8314.32}{18}=461.9066667 J/(kg K) But in tutorial R equal to 3000 J/(kg K).
compressibleInterFoam : biphasic, compressible, equation of state

I was looking for an explanation of R and I found your post. I think your calc is correct.
According to a previous post, I think that value 3000 is to give an incompressible behavour to liquid phase of specie; 461.9 should refer to compressibility factor for vapour phase of water ...just a trick...should it be?

 January 22, 2024, 11:04 #5 New Member   Nainah Join Date: Jan 2024 Posts: 3 Rep Power: 2 Hi there, In the compressibleInterFoam solver, how can the value of air density be adjusted? Thank you