# TwoPhaseEulerFoam viscosity models

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 May 20, 2008, 02:59 I compared the equations in th #1 Member   Juho Peltola Join Date: Mar 2009 Location: Finland Posts: 80 Rep Power: 8 I compared the equations in the source code of the Gidaspow and Syamlal viscosity models of twoPhaseEulerFoam to those presented in the Fluent 6.3 manual. In both models the first term equals to the collisional viscosity equation in the Fluent manual multiplied by alpha. The other terms in the Gidaspow model also equal the Gidaspow's kinetic viscosity model in the Fluent manual multiplied by alpha. However, in the Syamlal model the rest of the terms equal the Fluent's Syamlal's kinetic viscosity model _without_ the multiplication by alpha. Openfoam Gidaspow = Fluent 6.3 Manual ( 23.5-63 + 23.5-65 ) * alpha Openfoam Syamlal = Fluent 6.3 Manual 23.5-63 * alpha + 23.5-64 Gidaspow: =============================================== return rhoa*da*sqrt(Theta)* ( (4.0/5.0)*sqr(alpha)*g0*(1.0 + e)/sqrtPi + (1.0/15.0)*sqrtPi*g0*(1.0 + e)*sqr(alpha) + (1.0/6.0)*sqrtPi*alpha + (10.0/96.0)*sqrtPi/((1.0 + e)*g0) =============================================== Syamlal: =============================================== return rhoa*da*sqrt(Theta)* ( (4.0/5.0)*sqr(alpha)*g0*(1.0 + e)/sqrtPi + (1.0/15.0)*sqrtPi*g0*(1.0 + e)*(3.0*e - 1.0)*sqr(alpha)/(3.0 - e) + (1.0/6.0)*alpha*sqrtPi/(3.0 - e) ); =============================================== Is there a reason for the difference or is it a bug?

 May 20, 2008, 04:44 It's an error in the Fluent 6. #2 Member   Juho Peltola Join Date: Mar 2009 Location: Finland Posts: 80 Rep Power: 8 It's an error in the Fluent 6.3 manual. It has been corrected in the newest manual. In the new manual the equations are identical to twoPhaseEulerFoam's equations.

 May 20, 2008, 11:31 Good :-) A. #3 Senior Member   Alberto Passalacqua Join Date: Mar 2009 Location: Ames, Iowa, United States Posts: 1,894 Rep Power: 26 Good :-) A. __________________ Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as live DVD/USB, hard drive image and virtual image. OpenQBMM - An open-source implementation of quadrature-based moment methods

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