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How to specify both the mixture velocity and solid volume fraction at the inlet? 

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April 14, 2020, 22:05 
How to specify both the mixture velocity and solid volume fraction at the inlet?

#1 
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Min Zhang
Join Date: Mar 2017
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Ansys/Fluent/Multiphase
Hello All, I am using the EulerianEulerian twofluid model (in Ansys Fluent) to simulate the solidliquid twophase flow in a horizontal pipe. This is the reference paper I am trying to reproduce: EulerianEulerian Simulation of ParticleLiquid Slurry Flow in Horizontal Pipe Titus Ntow Ofei and Aidil Yunus Ismail I want to specify both the mixture velocity (the liquid and solid have the same inlet velocity) and solid volume fraction at the inlet. Initially, I was using "velocityinlet" but I couldn't define the volume fraction. Then I used "massflowinlet", where the mass flow rate of both liquid and solid phases is calculated based on inlet velocity, solid volume fraction, liquid and solid densities, inlet area, etc. So I am wondering whether I am doing it right? Thanks! 

April 15, 2020, 06:48 
Volume Fraction

#2 
Senior Member

When you use velocity inlet, there is option is choose volume fraction for all the secondary phases under the inlet. This option will appear as a separate tab within velocity inlet option for secondary phase not for primary phase.
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April 15, 2020, 11:44 
Yes!

#3 
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Min Zhang
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You are right! Thanks!
For the "Velocity inlet" of the solid phase, how to specify the Granular Temperature? I know that the granular temperature is related to the "the mean square of particle velocity fluctuations", but how could I know the "particle velocity fluctuations"? For the "Turbulence" parameters of the solid phase, if the solid inlet velocity is the same as the liquid phase, these parameters would be the same as the liquid phase, right? 

April 15, 2020, 12:40 
Granular Temperature

#4 
Senior Member

Just like turbulence intensity, you can assume a similar fluctuations since the fluctuations are because of turbulence.
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April 15, 2020, 17:18 
Calculate Granular Temperature at the inlet

#5 
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Min Zhang
Join Date: Mar 2017
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This is my way:
The main reference is here: https://www.afs.enea.it/project/nept...ug/node238.htm I estimated Turbulent Kinetic Energy (k) and Turbulent Dissipation Rate (epsilon), and then I calculated "continuous/liquid phase mean square velocity fluctuations" = 2/3*k. Then, the "solid phase mean square velocity fluctuations" = C^2*"continuous/liquid phase mean square velocity fluctuations", where C is a function of Stokes number (that is the ratio of particle relaxation time and turbulence time). Finally, the granular temperature = 1/3*"solid phase mean square velocity fluctuations". Your valuable comments would be greatly appreciated! In addition, I am wondering whether a small difference of these turbulence related parameters' values will make a difference in the simulation results. 

April 16, 2020, 03:07 
Granular Temperature

#6 
Senior Member

You are right; a small difference at boundaries won't affect your simulation. So, you can go ahead. The field inside the domain very quickly adjusts to the turbulence field.
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April 16, 2020, 11:59 

#7 
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Min Zhang
Join Date: Mar 2017
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inlet boundary condition 
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