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July 11, 2013, 05:48 |
need help**
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#1 |
Senior Member
Govindaraju
Join Date: Apr 2010
Posts: 209
Rep Power: 17 |
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 |
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July 11, 2013, 18:07 |
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#2 |
Senior Member
Erik
Join Date: Feb 2011
Location: Earth (Land portion)
Posts: 1,167
Rep Power: 23 |
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. |
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