The wind load from a south wind makes intuitive sense, with positive pressures on the wall facing the wind, and negative pressures in the lee of the building. The magnitude of the forces are similar to what would be predicted from the building codes. Pressures are shown below.
However, the results from a north wind don’t make sense. Even the vertical wall facing into the wind has substantial negative pressures. Every part of the building has negative pressure, and the magnitudes are significantly greater than what would be predicted from building codes. Pressures are shown below.
If the wind is from the northwest, the resulting pressures are quite different, and make more intuitive sense. Positive pressures facing into the wind, and negative pressures on the lee side, with reasonable magnitudes. Pressures are shown below.
I have also tried running the simulation with winds from two other directions, southeast and east/west. However, both of these simulations failed. One because the pressure field started diverging, the other because the velocity field started diverging. Not sure of the cause of that?