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twoPhaseEulerFoam: Defining angle of repose and viscosity for solid phase

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Old   January 16, 2018, 07:24
Default twoPhaseEulerFoam: Defining angle of repose and viscosity for solid phase
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Lennart Steffen
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Dear Foamers,

I am currently trying to model a two-phase system of water and quartz sand using twoPhaseEulerFoam. My simulation runs smoothly, but does not produce accurate results: The sand is moved very easily and does not seem to offer enough shear resistance.

Therefore, my question is: How do I make the sand behave more rigid and more resistant to shear?

The thermophysicalProperties dict for the solid phase currently looks like this:

Code:
thermoType
{
    type            heRhoThermo;
    mixture         pureMixture;
    transport       const;
    thermo          hConst;
    equationOfState rhoConst;
    specie          specie;
    energy          sensibleInternalEnergy;
}

mixture
{
    specie
    {
        nMoles      1;
        molWeight   60;
    }
    equationOfState
    {
        rho         2650;
    }
    thermodynamics
    {
        Cp          2000; //2000 for rock, 730 for quartz sand
        Hf          0;
    }
    transport
    {
        mu          1e-3;
        Pr          1;
    }
}
Changing mu (the viscosity) had no discernible effect. Furthermore, it is unclear to me how to define an angle of repose, which is more appropriate for a solid phase than a viscosity. My search for the topic turned up empty.

Any help would be greatly appreciated.
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Old   January 16, 2018, 07:44
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Have you checked this paper:

https://pdfs.semanticscholar.org/b5c...0d92eec4b4.pdf
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Old   January 16, 2018, 07:54
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Lennart Steffen
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Thanks for the quick reply. I just checked the paper you proposed. It is about ANSYS Fluent, not OpenFOAM. Therefore, it does not help me with my OpenFOAM problem. But thank you nonetheless.
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Old   January 25, 2018, 23:14
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Kai Jiang
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Quote:
Originally Posted by RL-S View Post
Dear Foamers,

I am currently trying to model a two-phase system of water and quartz sand using twoPhaseEulerFoam. My simulation runs smoothly, but does not produce accurate results: The sand is moved very easily and does not seem to offer enough shear resistance.

Therefore, my question is: How do I make the sand behave more rigid and more resistant to shear?

The thermophysicalProperties dict for the solid phase currently looks like this:

Code:
thermoType
{
    type            heRhoThermo;
    mixture         pureMixture;
    transport       const;
    thermo          hConst;
    equationOfState rhoConst;
    specie          specie;
    energy          sensibleInternalEnergy;
}

mixture
{
    specie
    {
        nMoles      1;
        molWeight   60;
    }
    equationOfState
    {
        rho         2650;
    }
    thermodynamics
    {
        Cp          2000; //2000 for rock, 730 for quartz sand
        Hf          0;
    }
    transport
    {
        mu          1e-3;
        Pr          1;
    }
}
Changing mu (the viscosity) had no discernible effect. Furthermore, it is unclear to me how to define an angle of repose, which is more appropriate for a solid phase than a viscosity. My search for the topic turned up empty.

Any help would be greatly appreciated.
Hello,Lennart Steffen
I am also trying to model two-phase system using twoPhaseEulerfoam, but ,my simulaiton isn't successful. So, i want to learn the setting of your case. Can i discuss the problem about the initial condition setup with you?
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Old   February 2, 2018, 13:29
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Lennart Steffen
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@Jack_Kerouac: Go ahead, I accepted your request.

On topic of the original question:

It looks like the value for mu in thermophysicalProperties is just a dummy. Solid phase stresses are implemented as a turbulence model.
This model, kineticTheory, has a couple of sub-models. One of them is viscosity, and no constantCoefficient model is available. Therefore, it is not possible to just increase the simulated solid phase viscosity manually.
Another sub-model pertains to frictional stress, i.e. the stress that occurs at phase fractions approaching the closest packing, when particles are not interacting in binary collisions anymore, but instead tend to stay in sustained contact. For both frictional stress models, JohnsonJackson and Schaeffer, the parameter phi in the respective subdict represents the angle of repose in degrees.

So far, no progress has been made on getting the bed to behave more rigidly, however.
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Old   February 2, 2018, 13:38
Default twoPhaseEulerFoam-pipeline(3D)- diverges
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Quote:
Originally Posted by RL-S View Post
@Jack_Kerouac: Go ahead, I accepted your request.

On topic of the original question:

It looks like the value for mu in thermophysicalProperties is just a dummy. Solid phase stresses are implemented as a turbulence model.
This model, kineticTheory, has a couple of sub-models. One of them is viscosity, and no constantCoefficient model is available. Therefore, it is not possible to just increase the simulated solid phase viscosity manually.
Another sub-model pertains to frictional stress, i.e. the stress that occurs at phase fractions approaching the closest packing, when particles are not interacting in binary collisions anymore, but instead tend to stay in sustained contact. For both frictional stress models, JohnsonJackson and Schaeffer, the parameter phi in the respective subdict represents the angle of repose in degrees.

So far, no progress has been made on getting the bed to behave more rigidly, however.
Hi,Lennart Steffen
Thanks for your reply.
***************************
my current project is as follows:
I want to discuss a problem about two phase system of water and solid particle( slurry flow in 3D pipeline ) using twoPhaseEulerFoam.
**********************************************
The basic description about the problem i'm studying:
1.the solid-liquid two phase flow, that is slurry flow.
2.This is an isothermal flow. So, It doesn't have to solve the temperature equation from the document-"twoPhaseEulerFoam.C".
3.It is considered that the drag force and turbulent diffusion force affect the interphase momentum exchange.
4.the volume fraction of solid particle is more than or equal to 0.2.
5.the initial inlet velocity of water is 0.4m/s. the initial lnlet velocity of solid particle is 0.4m/s.
************************************************
The problem i met :
The calculation has always been divergent and the terminal display for P_rgh, the number of iterations is always more than 500.
**************************************************
Now, i can't solve the problem.
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Old   February 2, 2018, 13:43
Default twoPhaseEulerFoam-pipeline(3D)- diverges
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Kai Jiang
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Quote:
Originally Posted by Jack_Kerouac View Post
Hi,Lennart Steffen
Thanks for your reply.
***************************
my current project is as follows:
I want to discuss a problem about two phase system of water and solid particle( slurry flow in 3D pipeline ) using twoPhaseEulerFoam.
**********************************************
The basic description about the problem i'm studying:
1.the solid-liquid two phase flow, that is slurry flow.
2.This is an isothermal flow. So, It doesn't have to solve the temperature equation from the document-"twoPhaseEulerFoam.C".
3.It is considered that the drag force and turbulent diffusion force affect the interphase momentum exchange.
4.the volume fraction of solid particle is more than or equal to 0.2.
5.the initial inlet velocity of water is 0.4m/s. the initial lnlet velocity of solid particle is 0.4m/s.
************************************************
The problem i met :
The calculation has always been divergent and the terminal display for P_rgh, the number of iterations is always more than 500.
**************************************************
Now, i can't solve the problem.
The checkMesh is ok.
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Old   February 2, 2018, 13:53
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Lennart Steffen
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I'll answer you in a PM, because your question is not really on topic here. You may, however, open a new thread if you so choose.
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Old   February 2, 2018, 14:17
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OK, Thank you.
I have opened the new thread. the name of thread is"For P_rgh, the number of iterations is always greater than 500. Reply to Thread"
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angle of repose, openfoam, solid, twophaseeulerfoam, viscosity

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