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-   -   ANSYS CFX volume fraction definition for multiphase simulation (http://www.cfd-online.com/Forums/cfx/91069-ansys-cfx-volume-fraction-definition-multiphase-simulation.html)

 juliom July 29, 2011 09:25

ANSYS CFX volume fraction definition for multiphase simulation

Dear Collegues,
I have been working on my thesis of master degree, It is related to multiphase fluid flow simulation, especifically in: gas-liquid vertical gravitational separator.
I´m working in ANSYS CFX and the most difficult part is to setup the volume fraction at the inlet.
The main goal of the thesis is to evaluate the separation process within the vessel, but the data used is from the real process, for example:
Oil rate, gas rate, pressure, densities, viscocity and so on..
THE VOLUMEN FRACTION DOES NOT APPEAR IN NO DATA SHEET.
How can I get this volume fraction?

 Zahid Ibrahim November 6, 2013 01:47

Quote:
 Originally Posted by juliom (Post 318041) Dear Collegues, I have been working on my thesis of master degree, It is related to multiphase fluid flow simulation, especifically in: gas-liquid vertical gravitational separator. I´m working in ANSYS CFX and the most difficult part is to setup the volume fraction at the inlet. The main goal of the thesis is to evaluate the separation process within the vessel, but the data used is from the real process, for example: Oil rate, gas rate, pressure, densities, viscocity and so on.. THE VOLUMEN FRACTION DOES NOT APPEAR IN NO DATA SHEET. How can I get this volume fraction? please help me
Hi I'm new in use (cfx-14) I want the different volume fraction. Actually my problem is water and air flow through straight pipe. Can somebody tell how I can get the lower half of pipe fill in water and the upper half fill in air.

Help urgently required

Thanks

 Antanas November 6, 2013 06:30

Quote:
 Originally Posted by Zahid Ibrahim (Post 460770) Hi I'm new in use (cfx-14) I want the different volume fraction. Actually my problem is water and air flow through straight pipe. Can somebody tell how I can get the lower half of pipe fill in water and the upper half fill in air. Help urgently required Thanks
You should refer to CFX tutorial 9. Look at expressions for UpVFAir, UpVFWater and DownVFAir, DownVFWater

 Zahid Ibrahim November 7, 2013 14:19

Hi, Sorry but I read Tutorial 9: Flow Through a Butterfly Valve and I don't found any expressions for UpVFAir, UpVFWater and DownVFAir, DownVFWater.

Help urgently required

Thanks

 juliom November 7, 2013 15:23

You have two options. You can either define the volumen fraction through an user define function (UDF) or during your meshing process and your modelling at Design modeler or whichever you use, you can have the inlet Split by two parts. In each part you will have a boundary condition and there you will be able to define the volumen fraction at each one!!

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