[minzhang]

Ansys/Fluent/Multiphase

Hello All,

I am using the Eulerian-Eulerian two-fluid model (in Ansys Fluent) to simulate the solid-liquid two-phase flow in a horizontal pipe.
This is the reference paper I am trying to reproduce:
Eulerian-Eulerian Simulation of Particle-Liquid Slurry Flow in Horizontal Pipe
Titus Ntow Ofei and Aidil Yunus Ismail

Initially, I didn't know how to give the viscosity value of the solid phase. Then, I choose to use "kinetic-theory" to calculate the viscosity (please see the attachment1). Then I found that, I am solving two energies equations (Energy-p1 and Energy-p2) (please see the attachment2). I am wondering why? Am I supposed to solve the energy equations?

I know that, for the solid phase calculation, such as pressure and viscosities, I am supposed to use the granular kinetic theory. In the "Multiphase Model" settings, I already set the "Partial Differential Equation" Granular Temperature Model.

In addition, my simulation could not converge.

Your valuable comments would be greatly appreciated!

[minzhang]

These are the attachments.
Thanks!

[vinerm]

Kinetic theory uses temperature to determine viscosity. If you you use kinetic theory to determine viscosity then temperature field is required. Though its on user whether he wants to solve this field or not. However, if you do not solve it then the viscosity is fixed and you don't really need to use kinetic theory. Do note that fixed does not imply that it is homogeneous.

Granular kinetic theory implies granular model and not a model for viscosity.

[minzhang]

Thanks for the reply!

In the "Multiphase Model - Phases - solid secondary phase", I chose the models for the Granular Viscosity, Granular Bulk Viscosity, Frictional Viscosity calculations, please see the attachment. So I think the solid phase viscosity is calculated by these models I choose here. Is that right?

So I am wondering why I still need to specify the viscosity in "Materials - Fluid - silicon solid"?

Thanks!

Originally Posted by vinerm

Kinetic theory uses temperature to determine viscosity. If you you use kinetic theory to determine viscosity then temperature field is required. Though its on user whether he wants to solve this field or not. However, if you do not solve it then the viscosity is fixed and you don't really need to use kinetic theory. Do note that fixed does not imply that it is homogeneous.

Granular kinetic theory implies granular model and not a model for viscosity.

[vinerm]

In Euler-Euler model. Navier-Stokes equations are solved for all the phases. The diffusion component require viscosity. The granular model provides extra stresses but diffusion component has its own role to play due to viscosity. However, the molecular viscosity plays role in a very small, low Re zone. So, you can use some small number, comparable to the primary phase.

[minzhang]

Hello Vinerm,
Thanks for your reply. Let me read more about the solid phase viscosity.

[vinerm]

Yes, reading is always, always helpful.