# densit.f-subroutine

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 July 9, 2007, 09:45 densit.f-subroutine #1 Hanti Guest   Posts: n/a Hello Could someone tell me how to write a densit.f-file for a compressible medium like oil including the bulk modulus. It is mainly dependant on the pressure. Appreciate your help Thx Hanti

 July 10, 2007, 00:05 Re: densit.f-subroutine #2 Mike Guest   Posts: n/a Include the speed of sound in DENDP, which is a function of bulk modulus and density ~~ 1300 m/s. Let me know if this works !!

 July 10, 2007, 03:27 Re: densit.f-subroutine #3 Richard Guest   Posts: n/a To be precise, DENDP is not the speed of sound, it is d(density)/d(pressure) at constant temperature. The speed of sound is the square root of d(density)/d(pressure) at constant entropy.

 July 10, 2007, 04:08 Re: densit.f-subroutine #4 Hanti Guest   Posts: n/a If I have initialized my model with 100 bar, do i have to substract the 100 bar from PR? Because the pressure values i get are strange (too high, about 300.000). Or has it something to do that in my model there is no pressure boundary and no in- or outlet???

 July 10, 2007, 05:17 Re: densit.f-subroutine #5 Richard Guest   Posts: n/a The variable PR is relative to PREF. It's likely that your equation of state is in terms of absolute pressure, in which case you have to be careful to code (PR+PREF) in densit when you want pressure.

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