# ANSYS CFX volume fraction definition for multiphase simulation

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 July 29, 2011, 09:25 ANSYS CFX volume fraction definition for multiphase simulation #1 Senior Member   Julio Mendez Join Date: Apr 2009 Location: Greensboro, U.S.A Posts: 177 Rep Power: 9 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 Zahid Ibrahim likes this.

November 6, 2013, 01:47
#2
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Zahid Ibrahim Mohammed
Join Date: Jul 2013
Posts: 4
Rep Power: 5
Quote:
 Originally Posted by juliom 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

November 6, 2013, 06:30
#3
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Join Date: Feb 2011
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Quote:
 Originally Posted by Zahid Ibrahim 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

 November 7, 2013, 14:19 #4 New Member   Zahid Ibrahim Mohammed Join Date: Jul 2013 Posts: 4 Rep Power: 5 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

 November 7, 2013, 15:23 #5 Senior Member   Julio Mendez Join Date: Apr 2009 Location: Greensboro, U.S.A Posts: 177 Rep Power: 9 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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