Is it possible to use this set of boundary conditions in Fluent for 2D pipe flow:

Pressure inlet and constant mass flow rate?

For compressible flow: Total Pressure inlet & Static Pressure outlet

or

Mass Flow Inlet & Static Pressure Outlet

For incompressible flow: Velocity inlet & outlet condition

Hi!

I'm not shure what you want. Maybe you have the same problem as me...I have a known upstream pressure and velocity, but in Fluent you can't define both parameters on inlet bc. What I do is I define velocity inlet and pressure outlet (upstream pressure - pressure losses in pipe), and after simulation converges check if the pressure on inlet agrees with experimental one.

It's a bit awkward solution but I think most of the people with this problem solve it this way...

regards

MATEUS

Thanks all. I am suprised that Fluent doesn't have a constant mass flowrate outlet boundary condition.

I think the outlet boundary condition 'outflow' may help you for your problem and get constant mass flow rate. thomas

constant mass flow rate is controled by approciate pressure. this may be the reason for no boundary conditions of constant mass flow rate in fluent software.

Note that outflow boundaries cannot be used in the following cases:

if a problem includes pressure inlet boundaries; use pressure outlet boundary conditions (see Section 6.8) instead

For non critical flow, the mass flow rate is governed by both inlet and outlet pressures. To obtain a constant mass, it seems that I should use constant pressure inlet and try-and-error outlet pressure. Is this a correct way?

for the compressible flow,you can use these boundary condition:"Mass Flow Inlet & Static Pressure Outlet " then you have made the mass flow as a constant when you define the "Mass Flow Inlet".

To be clear, the conditions I have are: constant mass flow rate and constant inlet pressure. But I don't know the downstream pressure. The question was: How to set the boundary conditions?