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-   -   two phase flow (https://www.cfd-online.com/Forums/fluent-multiphase/116811-two-phase-flow.html)

 sahand.g April 25, 2013 10:47

two phase flow

could anyone tell me, how to define a volume fraction of solid particles in two phase flow, in boundary condition?

 A CFD free user April 29, 2013 15:07

Hey
you have to patch it along with initialization not defining it in BC.

 sahand.g April 30, 2013 02:01

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 ?

 A CFD free user April 30, 2013 16:59

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

 manjunath June 12, 2013 13:36

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.

 oj.bulmer June 12, 2013 14:23

Volume fraction of 0.1, have you explored the DPM?

OJ

 manjunath June 12, 2013 14:46

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.

Thanks,
Manjunath

 hossein65 June 30, 2013 18:35

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

 alireza.razeghi February 8, 2014 04:15

Request Guidance

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?