Pressure loss by bouyantPressure
 

Hi,

I've got an issue about the bouyantPressure BC in sprayFoam.

In my tunnel case I have two side patches set to buoyantPressure with value 101300.

In the ceiling there is an inlet with pressure set to zeroGradient. Due to the hydrostatic pressure distribution air with a lower pressure than the mean pressure in the system is entering. Thus the pressure in the whole system is decreasing by time, supported by the buoyantPressure BC which adapts to the pressure of the internal field.

When I simply set the inlet pressure to 101300, I get an undesired acceleration by the overpressure. Setting the side patches' values to fixedValue will produce pressure driven flow from the internal field to the patch or vice versa. Deactivating gravity is no solution for me.

Please help me, I don't know how to fix this... :/

Robert