Leakage in star ccm+
 

Hi,
How is it possible to simulate room with open window? That is I want to consider the air leakage through the window.

I suppose you should use the 'buoyancy feature' and simulate air inside and outside the room.

Hi,
If you want to simulate the natural flow from the room through an open window, then it means that you have an over pressure inside.
The reason could be stack effect or wind effect.
For any case you need to define an inlet where the fresh air comes into the room. Then you will put your window as flow split outlet.