I am carrying out a numerical simulation of a hydrocyclone using FLUENT5.46,RSM modeling.

Firstly,I choose a simple modelne-phase(water),2D,axisymmetric.

As you know,a hydrocyclone has an inlet and two outlets, in "boundary conditions",I define the inlet as "velocity inlet", and the two outlets(overflow and underflow) as "outflow", the problem is: in RSM modeling, you must give a "Flow Rate Weighting" for all outflow boundaries(between 0 and 1), in my simulation the overflow and underflow are not equal, but I do not know the exact fraction of each outflow, so how could I define the "Flow Rate Weighting"?

Any suggestion is urgent! Thanks a lot!

Hi,
Have you tried the pressure-outlet condition? In this kind of BC you don't need to specify this weighted flowrate. You only need to specify the gauge pressure distribution and the turbulent parameters.
Regards, cfd guy

Use Pressure Outlet. Do not use outlet.

use pressure outlet, not outflow

All replying posting is correct. Use pressure outlet rather than outflow. But you should know the static pressure of both outlet. The problem is, in most cases, the static pressure at the two outlet is not the same and fairly difficult to obtain.

Sincerely, Jinwook