# twoPhaseEulerFoam: Defining angle of repose and viscosity for solid phase

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 January 16, 2018, 07:24 twoPhaseEulerFoam: Defining angle of repose and viscosity for solid phase #1 New Member   Lennart Steffen Join Date: Mar 2017 Location: Braunschweig, Germany Posts: 17 Rep Power: 5 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.

 January 16, 2018, 07:44 #2 Senior Member   Join Date: Aug 2014 Location: Germany Posts: 292 Rep Power: 10 Have you checked this paper: https://pdfs.semanticscholar.org/b5c...0d92eec4b4.pdf

 January 16, 2018, 07:54 #3 New Member   Lennart Steffen Join Date: Mar 2017 Location: Braunschweig, Germany Posts: 17 Rep Power: 5 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.

January 25, 2018, 23:14
#4
New Member

Kai Jiang
Join Date: Aug 2017
Posts: 19
Rep Power: 5
Quote:
 Originally Posted by RL-S 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?

 February 2, 2018, 13:29 #5 New Member   Lennart Steffen Join Date: Mar 2017 Location: Braunschweig, Germany Posts: 17 Rep Power: 5 @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.

February 2, 2018, 13:38
twoPhaseEulerFoam-pipeline(3D)- diverges
#6
New Member

Kai Jiang
Join Date: Aug 2017
Posts: 19
Rep Power: 5
Quote:
 Originally Posted by RL-S @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
***************************
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.

February 2, 2018, 13:43
twoPhaseEulerFoam-pipeline(3D)- diverges
#7
New Member

Kai Jiang
Join Date: Aug 2017
Posts: 19
Rep Power: 5
Quote:
 Originally Posted by Jack_Kerouac 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.
Attached Images
 code.png (138.9 KB, 6 views)

 February 2, 2018, 13:53 #8 New Member   Lennart Steffen Join Date: Mar 2017 Location: Braunschweig, Germany Posts: 17 Rep Power: 5 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.

 February 2, 2018, 14:17 #9 New Member   Kai Jiang Join Date: Aug 2017 Posts: 19 Rep Power: 5 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"

 Tags angle of repose, openfoam, solid, twophaseeulerfoam, viscosity