[Belimane]

In Ansys fluent, during the simulation of an upward fluid flow through a vertical tube (which has a complicated geometry and variable fluid rheology characteristics), we have the boundary condition at the outlet (P_out) then using simulation, we get the results at the inlet (P_in). then, we will play on the rheology and some other conditions, so that the simulation result (P_in) will change.
To control and maintain the pressure at the inlet (the result of the simulation) constant, we want to adjust and play on the the boundary condition (P_out).
.........
My question is... can i estimate the values of
(P_out) so that (P_in) stays constant. And How?
Thanks in advance.

[vinerm]

The question is not very clear. If inlet pressure is required to be constant, you may just set it as Pressure Inlet Boundary Condition. If you want static pressure to be constant at the inlet, then set a value of total pressure, go to initialization tab, enable standard initialization, and choose Inlet boundary under Initialize From. It will calculate static pressure and show the value. Modify the total pressure until you get the desired value.

Please provide more description, if I have misunderstood your requirement.