Hydrostatic Pressure Reference Point

brenton_101

Hi,

 

I am modelling heat transfer, (natural and forced convection) of a cabinet with an internal heat source. Please see attached figure.

 

I am using the Boussinesq approximation and including gravity so need to use 'Hydrostatic pressure on' setting.

 

Can someone please explain where to set the hydrostatic pressure origin?

 

Am I right to assume it is in the middle of my outflow surface that is venting to atmosphere?

 

Thanks in advance.

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acupro

I don't believe it matters too much what you use for the origin, so long as every boundary where you activate it you use the same origin.  Your choice is to put it on that outflow surface is reasonable.  Assuming up/down in the image is also the gravity direction, you probably do not need to activate hydrostatic on the outlet surface.  It only has effect on a boundary that has any component parallel to the gravity direction.  If you used a pressure or stagnation pressure type at the Inflow as pictured, you would need to use hydrostatic pressure there.  It basically makes the pressure value at the boundary consistent with the gravity body force.  The outlet at the top really wouldn't see any pressure gradient due to gravity as that surface is normal to the applied gravity.