[alirezame]

Hello,


I am simulating three-phase slurry case using water, air and solid (slurry defines as solid and water with solid.vf=65%). Inlet is slurry (65% solid and 35%water) defined as mass flow rate and initially air was inside the mixing tank.

I have defined all phases a a continius phase (I defined solid as a liquid phase while the viscosity changes based on the volume fraction) and have done inhomogenious (standard free surface) simulation. I defined free surface for the water-air and air-solid phases while I defined mixing model for the solid-water phases. After convergence, the results is not reaistic and all phases are seperated. there is no mixing. Then I set the intereface compression level to zero, but it did not help.

There is no heat transfer and surface tention.

I would appreciate if you can inform me how can I improve the simulation accuracy to get mixture of the water and solid.

Best regards

[Gert-Jan]

Do you mean that in the end the solids are at the bottom, air at the top and water in the middle? So, the phases separate. But isn't that logical? The end situation will be that the solids will be at the bottom. Or isn't that what you intend?

In other words, it is unclear what you want to simulate.......... Do you intend to study the filling of a vessel with a slurry and see where the solids are at the time you switch off the pump?

[alirezame]

Thanks for your post.
Actually the expectation is to have a mixture of water and solid but different in volume fraction, maximum 0.6. there should not be any free surface between the water and solid in the reality. Slurry comes in and there is a mixer rotating inside the tank which affects the slurry volume fraction, but should not be separated completely.

[Gert-Jan]

Lets state it differently: What question are you trying to answer using CFD? What problem are you trying to tackle?
Also, I wonder....... you have a solids volume fraction of 65%. That is very, very high. I would expect that this is about the highest you can get in reality. You'll never obtain 100% since there will always be water present between the particles, unless they are cubes, and ideally positioned. So, is you question valid anyway?

But assuming you want to quantify the differences in solids fraction. If the solids fraction separate, then your interaction between solids and water is not set right. It is impossilbe to judge from here if you set everything correct. What settings did you use?

[alirezame]

Actually the aim is to find out that how long it takes for the slurry to exit and see the volume fraction along the mixer. I set mixing interaction between solid and water, and free surface between the solid-air and water-air. Do you think should I use homogenious instead of inhomogenious?

[Gert-Jan]

I am not talking about homogeneous or inhomogeneous, but the forces (drag, turbulent dispersion, etc) between the water and solids.

[alirezame]

Constant drag coefficient and laminar flow

[ghorrocks]

Please post an image of your geometry and setup, the results you are getting and the result you expect to get and your CCL.