CFD Online Discussion Forums

CFD Online Discussion Forums (
-   CFX (
-   -   need help** (

kmgraju July 11, 2013 05:48

need help**
I have question.
In my case initial pressure and velocity of the fluid is 140 mmHg and 0.4m/s . I don't know velocity and pressure at the outlet.

I set velocity at the inlet 0.4 m/s and mass flow rate at the outlet (mass flow rate= inlet velocity * density of the fluid)

I introduce initialization condition velocity 0.4m/s and pressure 140mmHg .

When I run the solution and check the monitor points , I could not find the inlet pressure is not 140 mmHg .Kindly help me how to proceed.

Thank you

evcelica July 11, 2013 18:07

compressible flow? If so then your boundary conditions are underconstrained.
If incompressible then it doesn't matter since it is only a relative pressure.

I'm not sure if this will work, but you could try to Define Outlet Pressure as:
(140mmHg - (areaAve(Pressure)@inlet - areaAve(Pressure)@outlet))
and define inlet with your 0.4 m/s
One thing that might help is making a good initial condition pressure guess that includes the pressure drop through the geometry.

You could also iterate your outlet pressure using a monitor point and change it while its running to achieve your desired inlet pressure.

All times are GMT -4. The time now is 12:12.