Learning Forum

[minzhang20]

Hello All,

I am using the Eulerian-Eulerian two-fluid model (in Ansys Fluent) to simulate the turbulent 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

 

But my simulation is not converging.

For the current model:

1. I reduced the inlet velocity to have a smaller Reynolds number (but it is still turbulent flow), it didn't converge.

2. I used a very small inlet velocity to have a laminar flow, it didn't converge.

3. I even established a new model on another reference paper. It did not converge, either. In this case, I think the mesh should be fine.

This is the reference:

Sand Transport and Deposition Behaviour in Subsea Pipelines for Flow Assurance. Yan Yang, Haoping Peng and Chuang Wen.

4. In addition, I saw some Console outputs before crashing:

Reversed flow on 2 faces of pressure-outlet 5.

Stabilizing epsilon to enhance linear solver robustness.

Stabilizing epsilon using GMRES to enhance linear solver robustness.

turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 465776 cells

 

Currently, I am thinking I might need to degrade my case further to ONLY simulate turbulent fluid flow first, then add the solid phase.

Your valuable comments would be greatly appreciated!

[minzhang20]

More info:

For the first reference paper:

The case I am trying to reproduce is: particle diameter = 270microns, particle volume fraction = 0.1.

The paper was using CFX and I am using Fluent.

The settings I am using are consistent with the settings mentioned in the paper. The settings that the paper did not mention and I think they might influence my simulation results are listed below.

In addition, there is a difference between their geometry and mine. In their paper, L=44D, and cell no. = 801,848. Since I am using the student free version and I have the limit of 512,000 cell number. So in my case, L=25D and my cell no. = 508,600. My mesh might be different from theirs but I think my mesh resolution should be fine compared with theirs. Please see the attached screenshot of my mesh.

My Scaled Residuals plot is also attached.

Your valuable comments would be very very appreciated!!

Settings were not mentioned in the paper:

1. Materials - Fluid - solid: what is the viscosity value? (1e-6 kg/(m.s))

2. Multiphase Model - Phases - Secondary Phase - Granular Conductivity: syamlal-obrien

3. Multiphase Model - Phases - Secondary Phase - Frictional Viscosity: shaeffer

4. Multiphase Model - Phases - Secondary Phase - Frictional Pressure: Johnson-et-al

5. Multiphase Model - Phases - Secondary Phase - Radial Distribution: lun-et-al

6. Multiphase Model - Phase Interaction - Forces - Drag Coefficient: gidaspow

7. Viscous Model - Turbulence Multiphase Model: Per Phase

8. Velocity Inlet - Turbulence - Turbulent Intensity: 3

    Velocity Inlet - Turbulence - Hydraulic Diameter: 0.0072

    Velocity Inlet - Granular Temperature: 0.007272

9. Pressure Outlet - Backflow Turbulent Intensity: 0

    Pressure Outlet - Backflow Turbulent Viscosity Ratio: 0

    Pressure Outlet - Backflow Granular Temperature: 0

    Pressure Outlet - Backflow Volume Fraction: 0

10: Wall - Granular Conditions: Johnson-Jackson

      Wall - Granular Properties - Restitution Coefficient: 0.2  

 

[ashishpeace]

Hi, I am working on similar problem. Have you been able to resolve this issue. In my case continuity was not converging. Also I coudnt observe suspension of sand particles. In my case, L=128D, cells= 280,000. Have you tried modifying the mesh.

 

best regards, Ashish