[Ordo]

Hi everyone

Inexperienced CFD user here. I'm trying to simulate the flow around a building in Ansys CFX, but I'm receiving some weird results, when I plot the velocities on my opening BC surfaces. The surface normal to Y axis and X axis are my inlets. There I've defined a logarithmic velocity profile. As I wanted to simulate different angles of attack of the wind, I've also split it into Y and X components. The other free surfaces (the ones displayed in the plot) I have defined as openings with reference pressure 0 Pa and Flow Direction normal to BC. The Walls of the building and the ground are defined as smooth walls.

Now, when I plot velocity on the opening BCs, I get these weird regions, where velocity is 0. These also move with my angle of attack, which is why I'm thinking it's not the mesh, that's causing problems, rather the BCs. I've also encountered this problem in another case, where the building geometry is slightly different, but all the BCs have been defined the same way.

Was also thinking about the height of the domain maybe not being large enough, currently the total height is 3 times the building height.

Any ideas, what this might be?
Would be grateful for any tips.