# Density as function of pressure

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 May 20, 2009, 15:08 Density as function of pressure #1 New Member   Santiago Orrego Join Date: Mar 2009 Posts: 9 Rep Power: 10 Hello Guys. Im making a steady simulation of a oil film. I need to establish the Density as function of pressure. rho=rho_initial*( (c1 + c2 * Pressure ) / ( c1 + Pressure ) ) Can anybody can please help me to establish that to the solver? Thanks a lot. Santiago.

 May 20, 2009, 15:42 #2 Member     Rui Igreja Join Date: Mar 2009 Location: Aveiro Posts: 68 Blog Entries: 1 Rep Power: 10 So far, what have you tried to set the density as that function of the pressure? __________________ Rui

 May 20, 2009, 18:04 #3 New Member   Santiago Orrego Join Date: Mar 2009 Posts: 9 Rep Power: 10 Hello. Thanks for reading. I try to create an expression called rho (and specify that expression in the Material propieties) rho= ((3e9+1.34*p)/(3e9+p)) * 860 [kg m^-3] But the solver said that the dimension are wrong. I tried several combinations of the dimensions and not succeded. Any ideas?? Thanks. Santiago

 May 20, 2009, 18:35 #4 Member   Jules Bell Join Date: May 2009 Posts: 31 Rep Power: 9 3e9 has no dimension, but 1.34*p has [Pa], that's why it doesn't work. -> try: ((3e9 [Pa] + 1.34*p)/3e9 [Pa] + p)) * 860 [kg m^-3] Regards, Jules

 May 21, 2009, 10:34 #5 New Member   Santiago Orrego Join Date: Mar 2009 Posts: 9 Rep Power: 10 Thanks Jules. It worked. I tryied that once, but the my mistake was that I was putting [pa] and not [Pa]. So. it finally worked using: ((5.9e8 [Pa] + 1.34*p) / (5.9e8 [Pa] + p) ) * 860 [kg m^-3] Bye! and thanks. Santiago

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