# Multiphase Modeling-Different Velocities at inlet

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 November 19, 2012, 01:24 Multiphase Modeling-Different Velocities at inlet #1 New Member   Kamyar Join Date: Nov 2009 Posts: 4 Rep Power: 10 Hi I am trying to simulate multiphase flow in a pipe. There are water, oil and air flowing simultaneously together. I could define three different regions for three phases by using field function. now I want to set a constant velocity for oil and water and different constant velocity for air. I do not know how to set it. anybody can help me? Thank You

 November 19, 2012, 11:55 #2 Senior Member   Reza Join Date: Mar 2009 Location: Appleton, WI Posts: 116 Rep Power: 10 I don't know if this will work or not, but it might be worth trying. If you have defined the volume fractions for the three phases, then just multiply the velocity that you want for each phase by that phase's volume fraction and add all three of these velocities: air inlet velocity * air vf + water inlet velocity * water vf + oil inlet velocity * oil vf This will give you the correct profile, I think.

 November 20, 2012, 01:40 #3 New Member   Kamyar Join Date: Nov 2009 Posts: 4 Rep Power: 10 The problem is that I want to have two different boundary conditions instead of one. Thanks for your suggestion though

 November 20, 2012, 09:22 #4 Senior Member   Reza Join Date: Mar 2009 Location: Appleton, WI Posts: 116 Rep Power: 10 What do you mean by different boundary conditions?

 November 20, 2012, 10:42 #5 New Member   Kamyar Join Date: Nov 2009 Posts: 4 Rep Power: 10 I want to have different constant values for liquid and gas phases. Oil and water need to have 0.5 m/s and air 1m/s velocity.

 November 20, 2012, 11:23 #6 Senior Member   Reza Join Date: Mar 2009 Location: Appleton, WI Posts: 116 Rep Power: 10 Then this field function should work: <0.5 m/s> * (\$oilvf + \$watervf) + <1 m/s> * \$airvf (you need to define these field functions: oilvf, watervf, and airvf for inlet.)

 November 22, 2012, 19:49 #7 Senior Member   Join Date: Oct 2009 Location: Germany Posts: 637 Rep Power: 15 Use an Eulerian-Eulerian approach. In STAR-CCM+ called segregated multiphase. A VOF approach is not suitable for doing this. __________________ We do three types of jobs here: GOOD, FAST AND CHEAP You may choose any two!

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