[engineerm]

How can I simulate a fan inside a room without knowingt boundary conditions of inlet and outlet such as velocity, mass flow rate and pressure ?

Thanks in advance.

[Jonas Holdeman]

You must specify SOMETHING as a boundary condition. When I look at ceiling fans at the store, the one specification always given is the flow rate. The flow rate can be specified by the difference in stream function across the blades in 2D or the line integral of the tangential component of the vector potential around the blades in 3D. No velocity or pressure drop is needed. About 10 years ago I modeled 2D flow in a room with an obstacle on the floor with a generic fan as a simple example. The result is shown in the attached figure. I have not tried the fan example in 3D, but have used the line integral to control flow in a 3D duct.