Hello,

I created a very tall tower (>1000m) and applied pressure boundary conditions at the inlet (bottom) and outlet (top) that correspond to the pressure are their relative altitudes. Gravity is turned on and set to 9.81 m/s^2. I was going to apply heat flux to the side of the model but without that I'd expect the air inside to be completely static. However, the air rushed out through the top of the tower as though it was not taking into account the effect of gravity. Have I missed something here or are pressure boundary conditions the wrong way to go about this problem?

Thanks.