Learning Forum

[Kirei]

Dear all,

I Intend to simulate slurry flow that consists of air, water, and ore, so it will be three phase simulation in Ansys CFX. The phase modeling that I did was:

1. Water: Continuous fluid
2. Air: Continuous fluid
3. Ore: dispersed solid

I used in-homogeneous multiphase model (with standard free surface model) and homogeneous turbulence model. I want to simulate a steady-state simulations of the slurry fills a box with one inlet and several outlets (at first the box is filled with air only).

I faced a problem when I modeled the ore particle-particle interaction with kinetic theory. The problem that I faced was the simulation was not converging. It showed residuals that do not converge and go up and down very unstable. However, when I turn of the kinetic theory model, the result can be obtained and more stable (even though it did not converged to the residual target, but still stable than when I turn on the kinetic theory model).

I already read several journal regarding multiphase flow that involves solid, activating kinetic theory model is best for modeling particle-particle interactions.

Does anyone have suggestions to solve this problem?

Thank you very much.

[CFD_Friend]

Hi Kirei,

The kinetic Theory model is suited for transient simulations. Have a look at this, these are modelling guides for solid particle collision models.

7.9.3. Kinetic Theory Models

Thanks

 

 

 

[CFD_Friend]

The fact that your simulation becomes unstable when you enable the kinetic theory model suggests that there may be issues with the model setup.

Check the mesh quality and make sure the time step size. Try reducing the time step size and see if it improves convergence.

[Kirei]

Dear CFD_Friend,

I already checked the model setup and I believe the setup is correct because I made a simulation comparison from a reference about water-sand modeling and it worked. So from your suggestion better to use transient simulation to simulate using the kinetic theory model?