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-   -   hydrostatic pressure (http://www.cfd-online.com/Forums/fluent/28871-hydrostatic-pressure.html)

Amanda August 29, 2001 23:48

hydrostatic pressure
 
Hi! In FLUENT, do the viscous models take care of the hydrostatic pressure? for exp, i have a close basin without any inflow and outflow, just run the laminar model, i can not observe the hydrostatic pressure distribution in the vertical direction. Anybody can help?

david August 30, 2001 00:34

Re: hydrostatic pressure
 
A) Have you considerd g ? gradivational accelation ? B) Put a right value and direction in operating conditons C) Solve again, and check the hydrostatic pressure now.

DC

Amanda August 30, 2001 01:53

Re: hydrostatic pressure
 
yes. i have already turn the gravity on. but the pressure appears to be zero

John C. Chien August 30, 2001 02:10

Re: hydrostatic pressure
 
(1). Can you get a sample case from the vendor? (2). If what you are saying is true, then you must be on the ISS (space station), or there is a black hole somewhere.

Anthony Wachs August 30, 2001 04:53

Re: hydrostatic pressure
 
Hi,

I already experienced that frustrating situation but I finally found the answer. The reason why you did not manage to see the hydrostatic pressure distribution might probably be the fact that you did not specify the operating density. To see the hydrostatic pressure distribution, you are to specify a operating density of 0. Actually, the operating density is a kind of reference density used by the solver to take into account the gravity source term, that can be written as :

(ro(fluid)-ro(oper))*g*V

where ro(fluid)=density of the fluid you consider

ro(oper)= operating density

g=gravity acceleration

V=volume

By defaults, if you do not specify ro(oper), the solver takes the same value as the fluid considered, e.g. ro(oper)=ro(fluid), then your gravity source term vanishes. That's why you could not see the hydrostatic pressure distribution. If you set ro(oper)=0, it will work !!

Hope it might help

Anthony

Amanda September 3, 2001 04:23

Re: hydrostatic pressure
 
Der Anthony, Thank you very very much! I solve the problems with your help!



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