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Verify Pressure Drop result by changing inlet boundary condition to pressure from flow rate

Question asked by Chris Mohn on Feb 18, 2020
Latest reply on Feb 20, 2020 by Ryan Dark



Is this statement correct?  In a flow simulation, the resulting velocity and pressure profile within an arbitrary pipe should be VERY similar between using pressure inlet / pressure outlet BC's vs flow rate inlet / pressure outlet BCs?  


In other words... If I ran a flow simulation using 1 GPM inlet flow rate and environmental pressure (atm) outlet and my surface goal was pressure drop between the inlet and outlet and this yielded a 2 psi pressure drop.  


Now if I set up the same flow simulation with (exact same geometry and mesh) with a inlet pressure of 2 psi higher than the environmental pressure outlet with a surface goal of max volumetric flow rate at the inlet... I should yield 1 GPM inlet flow rate correct?  And these two simulations should yield very similar if not exact velocity/pressure profiles correct?


I find running these two simulations (using the result of one sim as a boundary condition of the other) a good way to verify the simulation results.


However, I don't seem to be getting similar results and the velocity and pressure profiles are different.