CFD Online Logo CFD Online URL
Home > Forums > CFX

need help**

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   July 11, 2013, 05:48
Default need help**
Senior Member
Join Date: Apr 2010
Posts: 206
Rep Power: 8
kmgraju is on a distinguished road
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
kmgraju is offline   Reply With Quote

Old   July 11, 2013, 18:07
Senior Member
Join Date: Feb 2011
Location: Earth (Land portion)
Posts: 496
Rep Power: 10
evcelica is on a distinguished road
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.
evcelica is offline   Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 15:40.