# Boundary condition for Eulerian multiphase flow

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 August 29, 2015, 10:18 Boundary condition for Eulerian multiphase flow #1 New Member   Richard Lee Join Date: Mar 2014 Posts: 8 Rep Power: 12 I use the Eulerian-Eulerian multiphase flow model to solve the mass transfer in gas-solid fluidized bed. And I define 2 user-define-scalar (one in the primary gas phase, the other in the secondary solid phase). The problem I encountered is that the boundary conditions for the UDS in the secondary phase is invalid. No matter how I define the BC for this UDS (using DEFINE_PROFILE or constant), the computation results indicate that the BC for this UDS does not work. However, the BC for the UDS in primary phase is OK. This problem confused me for couple of weeks. I would be very appreciate if anybody can tells why?

 August 29, 2015, 15:29 #2 Senior Member   Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,683 Rep Power: 66 Is it related to the volume fraction? Maybe you are trying to calculate the scalar from the volume fraction of the 2nd phase? Can you instead use 1 - VF of the 1st phase?

August 29, 2015, 20:47
BC for UDS for EE multiphase flow model
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Richard Lee
Join Date: Mar 2014
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Quote:
 Originally Posted by LuckyTran Is it related to the volume fraction? Maybe you are trying to calculate the scalar from the volume fraction of the 2nd phase? Can you instead use 1 - VF of the 1st phase?
you mean the vof_s should be replaced by (1-vof_g) in the User-Define-Function? But the UDF using vof_s is working in my case, because a source term containing vof_s is added to the UDS (specified to the 2nd phase) and it works. Nevertheless, the inlet boundary condition (velocity inlet) for this UDS is invalid (seems that no matter what I define it, it becomes zero when calculating).

 January 8, 2016, 14:31 How to define a B.C in Eulerian-Eulerian model in Ansys Fluent? #4 New Member   parham Join Date: Oct 2015 Posts: 24 Rep Power: 10 I am trying to model two phase flow of oil and water in a horizontal pipe in which oil is introduced from a surface with diameter 30mm and water is injected from the annulus. the total diameter is 40mm. when I define a surface and annulus, I should define inlet velocity of oil and water for both surface and annulus and I dont want this. I want to define from surface only oil with specified velocity inlet and also inject water from annulus with velocity inlet. This option is only available for VOF model. How can I do it for Eulerian-Eulerian?

 Tags boundary condition, eulerian, multiphase model, user difine scalar