two phase flow

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 April 25, 2013, 10:47 two phase flow #1 New Member   sahand Join Date: Apr 2013 Location: tehran Posts: 10 Rep Power: 5 could anyone tell me, how to define a volume fraction of solid particles in two phase flow, in boundary condition? Parashuram likes this.

 April 29, 2013, 15:07 #2 Senior Member     A-A Azarafza Join Date: Jan 2013 Posts: 206 Rep Power: 6 Hey you have to patch it along with initialization not defining it in BC. tangfl likes this. __________________ Regard yours

 April 30, 2013, 02:01 #3 New Member   sahand Join Date: Apr 2013 Location: tehran Posts: 10 Rep Power: 5 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

 April 30, 2013, 16:59 #4 Senior Member     A-A Azarafza Join Date: Jan 2013 Posts: 206 Rep Power: 6 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 __________________ Regard yours

 June 12, 2013, 13:36 #5 New Member   Manjunath Join Date: Dec 2012 Location: Salt Lake City, Utah, USA Posts: 14 Rep Power: 5 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.

 June 12, 2013, 14:23 #6 Senior Member   OJ Join Date: Apr 2012 Location: United Kindom Posts: 475 Rep Power: 12 Volume fraction of 0.1, have you explored the DPM? OJ

 June 12, 2013, 14:46 #7 New Member   Manjunath Join Date: Dec 2012 Location: Salt Lake City, Utah, USA Posts: 14 Rep Power: 5 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

 June 30, 2013, 18:35 #8 New Member   Hossein Join Date: Oct 2010 Location: Greensboro, NC, USA Posts: 29 Rep Power: 8 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 __________________ Hossein Amini PhD student in Biochemical Engineering; Computational Science and Engineering department; North Carolina Agricultural and Technical State University

 February 8, 2014, 04:15 Request Guidance #9 New Member     alireza razeghi Join Date: Dec 2010 Posts: 14 Rep Power: 7 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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