# About kinetic Theory in twoPhaseEulerFoam

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 March 13, 2012, 11:31 About kinetic Theory in twoPhaseEulerFoam #1 Member   Charlie Join Date: Dec 2010 Location: 415 Kinross Dr. Newark, DE 19711 Posts: 80 Rep Power: 7 Hi, I'm using twoPhaseEulerFoam now to study sediment transport, and I'm courious about the kinetic theory part. In the kineticTheory.C we can see that the dissipation due to inelastic collision has missed a term tr(D) as the laster term, has anyone evaluated how important is this term? [QUOTE]// dissipation (Eq. 3.24, p.50) volScalarField gammaCoeff ( 12.0*(1.0 - sqr(e_))*sqr(alpha_)*rhoa_*gs0_*(1.0/da_)*ThetaSqrt/sqrtPi ); /QUOTE] Also, the J2 term, that is the fluctuation energy production due to fluid-particle slip, does anyone know the original paper that propose this formula? [QUOTE]volScalarField J2 ( 0.25*sqr(betaPrim)*da_*sqr(Ur) /(max(alpha_, scalar(1e-6))*rhoa_*sqrtPi*(ThetaSqrt + TsmallSqrt)) );/QUOTE] and the last and the most important question is that, the 'pa' and 'tau' in kinetic theory is really alpha*pa or just pa, since it's wierd that it does not have alpha in front of it, while in UaEqn, the pa is directly added as normal pressure ( solved in pEqn). the question is , in pEqn, we should add pa or (pa/alpha) ? in pEqn: [QUOTE]if (kineticTheory.on()) { phiDraga -= rUaAf*fvc::snGrad(kineticTheory.pa()/rhoa)*mesh.magSf(); } /QUOTE] Thank you very much!

 March 13, 2012, 11:34 Reference ? #2 Member   Charlie Join Date: Dec 2010 Location: 415 Kinross Dr. Newark, DE 19711 Posts: 80 Rep Power: 7 BTW, could anyone be kind enough to tell me where the reference of this kinetic theory is, since it has some comments in the code, however, I really don't know what they are referring to, Thanks!

 October 17, 2014, 09:38 #3 New Member   Josefine Wilms Join Date: Sep 2009 Posts: 10 Rep Power: 9 Berend van Wachem phd thesis. I got the full document by simply googling: Van Wachem phd thesis TUDelft. Kinetic theory for particles starts at page 78. openfoammaofnepo likes this.

April 8, 2016, 16:32
#4
Senior Member

Join Date: Jan 2013
Posts: 310
Rep Power: 6
Dear Charlie,

For this kinetic theory model, is it possible to use it as the particle phase LES model? Thanks. Did you have the experinece for that?

[QUOTE=cheng1988sjtu;349196]Hi,

I'm using twoPhaseEulerFoam now to study sediment transport, and I'm courious about the kinetic theory part.

In the kineticTheory.C we can see that the dissipation due to inelastic collision has missed a term tr(D) as the laster term, has anyone evaluated how important is this term?

[QUOTE]// dissipation (Eq. 3.24, p.50)
volScalarField gammaCoeff
(
12.0*(1.0 - sqr(e_))*sqr(alpha_)*rhoa_*gs0_*(1.0/da_)*ThetaSqrt/sqrtPi
);
/QUOTE]

Also, the J2 term, that is the fluctuation energy production due to fluid-particle slip, does anyone know the original paper that propose this formula?

[QUOTE]volScalarField J2
(
0.25*sqr(betaPrim)*da_*sqr(Ur)
/(max(alpha_, scalar(1e-6))*rhoa_*sqrtPi*(ThetaSqrt + TsmallSqrt))
);/QUOTE]

and the last and the most important question is that, the 'pa' and 'tau' in kinetic theory is really alpha*pa or just pa, since it's wierd that it does not have alpha in front of it, while in UaEqn, the pa is directly added as normal pressure ( solved in pEqn). the question is , in pEqn, we should add pa or (pa/alpha) ?

in pEqn:
Quote:
 if (kineticTheory.on()) { phiDraga -= rUaAf*fvc::snGrad(kineticTheory.pa()/rhoa)*mesh.magSf(); } /QUOTE] Thank you very much!

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