(Help)udf for inlet boundary condition
 

Hello，i want specify Instant velocity,u,v,w,for the inlet condition.The three velocities are related because the continue equation, they can be only produced on one run.
I used random function in define profile. So if i use three define profile functions for the three velocities,they can't fit the continuity.
How to manage it?
Thank you in advance

Maybe i can use external variables?

No. Check the equations: the continuity equation relates the derivatives of the velocity. Since you prescribe them on a surface, there is one derivative that you don't prescribe, and that one will follow from the continuity equation automatically.