Inlet/Outlet Boundary Conditions
Submitted by sdup on April 18, 2011 - 09:18
Two questions:
1. Is it possible, instead of assigning a velocity to fluid, to assign an inlet and outlet pressures? I realise this will imply some transient flow solutions.
2. How can one easily determine the stagnation pressure of the fluid at any position? One can get P (I assume static pressure) and U results. It should be relatively easy to combine those to give the stagnation pressure change. I’m thinking specifically in terms of determining pressure losses over industrial ventilation and pollution control equipment.
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Boundary Condition Types and use of Reference option
In answer to your questions:
Still seem to require a reference velocity
Managed easily to create new outputs. Thanks
However. I still seem to have to assign a velocity to the fluid else the analysis falls over easily.
Reference Velocity is Necessary
You'll always need to assign a Substance->Properties->Reference->U (Velocity), it's used by turbulent variables and by default (with options to override) it's used to initialize the velocity field. The reference velocity doesn't have to be exact - just in the right ballpark.
I've often seen that using a pressure inlet boundary condition will cause a simulation to converge much slower than the equivalent velocity inlet.
Another think to watch is to make sure you are using relative pressures (not absolute) for incompressible flows.