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Schiller Naumann with Mixture Model

Posted Jul 12, 2012, 6:58 a.m. EDT Fluid & Heat, Computational Fluid Dynamics (CFD), Studies & Solvers Version 4.2a 2 Replies

Rui Silva
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Hi folks,

I have been trying to use the Schiller Naumann with Mixture Model to simulate a particle flow in water.

I have previously used the Hadamard-Rybczynski model with smaller particles (Rep <1) and had no problems in getting a steady convergence.

However, the Schiller Naumann is not making it easy for me.
With larger particles and higher density I get a Rep roughly in 500. So, the Schiller Naumann applies, and I can't use the Hadamard-Rybczynski model for the drag anymore.

But, I can't seem to get a convergence with the the Schiller Naumann model. I have searched the forum and found that using P=0 in the initial conditions might be the problem so I used about 2000 Pa (rough estimate) but still no convergence. I have attached the convergence plot for a better understanding.

The segregated group 1 is P,V,PHID; The segregated group 2 is k and epsilon; and The segregated group 3 is the slipvel.

Does anyone have some experiences with this or any advices?

Best Regards,

Rui

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2 Replies Last Post Dec 15, 2012, 2:42 p.m. EST
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Hello Rui Silva

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Sin Kim
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Posted: 1 decade ago Dec 15, 2012, 11:03 a.m. EST


Hi Rui,

Sorry to bother you but I want to ask that were you able to achieve the convergence with the mixture model coz I am also facing prblems to achieve convergence. Can you plz let me know few tips and tricks. Which type of grid and scaling values you used in artifcial diffusion regarding NS equations and Discrete phase equation.

Kindest regards

Hi Rui, Sorry to bother you but I want to ask that were you able to achieve the convergence with the mixture model coz I am also facing prblems to achieve convergence. Can you plz let me know few tips and tricks. Which type of grid and scaling values you used in artifcial diffusion regarding NS equations and Discrete phase equation. Kindest regards
Rui Silva
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Posted: 1 decade ago Dec 15, 2012, 2:42 p.m. EST
Hello Sin Kim,

I used the mixture model with some modifications, and thus I had some issues with convergence.

If you are using the mixture model, with the Schillher-Naumann slip model, I have found that providing an estimate of the pressure drop and slipvel in the "Initial Values" really helps in the convergence process. Also, I had to use Inconsistent Stabilization for the Disperse Phase because I couldn't get a very fine mesh (due to RAM limitations of my server). In the Scaling for the stabilization I used the initial particle concentration.
Some other tips that I can provide:

- Try refining the mesh near the wall and use a boundary layer;
- Try decreasing the damping value for the segregated Newton Solver in the dispersed phase;

Hope this helps. If you would like you can upload your file and I can take a look at it.

Best Regards,

Rui Silva


Hi Rui,

Sorry to bother you but I want to ask that were you able to achieve the convergence with the mixture model coz I am also facing prblems to achieve convergence. Can you plz let me know few tips and tricks. Which type of grid and scaling values you used in artifcial diffusion regarding NS equations and Discrete phase equation.

Kindest regards


Hello Sin Kim, I used the mixture model with some modifications, and thus I had some issues with convergence. If you are using the mixture model, with the Schillher-Naumann slip model, I have found that providing an estimate of the pressure drop and slipvel in the "Initial Values" really helps in the convergence process. Also, I had to use Inconsistent Stabilization for the Disperse Phase because I couldn't get a very fine mesh (due to RAM limitations of my server). In the Scaling for the stabilization I used the initial particle concentration. Some other tips that I can provide: - Try refining the mesh near the wall and use a boundary layer; - Try decreasing the damping value for the segregated Newton Solver in the dispersed phase; Hope this helps. If you would like you can upload your file and I can take a look at it. Best Regards, Rui Silva [QUOTE] Hi Rui, Sorry to bother you but I want to ask that were you able to achieve the convergence with the mixture model coz I am also facing prblems to achieve convergence. Can you plz let me know few tips and tricks. Which type of grid and scaling values you used in artifcial diffusion regarding NS equations and Discrete phase equation. Kindest regards [/QUOTE]

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