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Old   April 25, 2013, 10:47
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could anyone tell me, how to define a volume fraction of solid particles in two phase flow, in boundary condition?
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Old   April 29, 2013, 15:07
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A-A Azarafza
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Hey
you have to patch it along with initialization not defining it in BC.
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Old   April 30, 2013, 02:01
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thank you for your answer
but, when you using pressure inlet and outlet BC. you have to define volume fraction of the solid particles...
I have mole fraction of products (in this case Alumina and other gas products) but i don't know how to turn it into the volume fraction of solids ?
thanks in advance
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Old   April 30, 2013, 16:59
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hey pal
I think it's not a CFD problem anymore, it's a chemical engineering problem. I suppose you need to use experimental methods to calculate volume fraction of the solid particles, here's a method I used for my thesis:
actually, I needed to patch a volume fraction in a specific zone of my stirred tank. I used this formula to calculate solid particles volume fraction:
volume fraction=(mass of solid / mass of solution)*(solution density/solid density)
hope it help
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Old   June 12, 2013, 13:36
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A CFD free user,

I am trying to simulate solid liquid flows in a stirred tank. I was able to set up and simulate the case for two phase flow, 100 micrometer diameter solid particles (VF = 0.1) in water using both Mixture and Eulerian model. I am interested in adding particles of different diameter (1000 micrometer dia, VF = 0.1) to the tank essentially creating a three phase solid-solid-liquid flow. I am getting divergence error if I solve for the volume fraction equations even if I start with a converged initial solution. Do you have any experience of setting up and simulating such flows.
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Old   June 12, 2013, 14:23
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Volume fraction of 0.1, have you explored the DPM?

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Old   June 12, 2013, 14:46
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OJ,

No I haven't explored the DPM approach because the total volume fraction of solids (0.1 + 0.1 = 0.2) is over 0.1. Dense DPM (DDPM) might work since it doesn't place a restriction on high VF, I feel DDPM is better suited but I haven't tried it. I will update on the forum if I am able to get it to work.

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Old   June 30, 2013, 18:35
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First, you have to define that you have a bed or you want to enter the particles?
if you have a bed, you have to patch a medium with a definite volume fraction of your material
if you want to enter a cloud of particles, then you have to define an injection and then define the size and material of your particles
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Old   February 8, 2014, 04:15
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Dear Friends
I am trying to model the nano-particles flow in a straight tube, but I have encountered a problem.
I define the nano-particles volume fraction in boundary conditions of fluent software and under the velocity input for second phase under the multiphase tab.
but after some iterations the magnitude of residuals decrease instantly to the 10^-15 order.
what is your opinion about it, is there any problems in setting the problem?
could you give more information about patching?
Thanks
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