# twoPhaseEulerFoam turbulence model

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 May 25, 2012, 07:50 twoPhaseEulerFoam turbulence model #1 Senior Member   Gerhard Holzinger Join Date: Feb 2012 Location: Austria Posts: 316 Rep Power: 26 Hello, I am trying to find out which equations are under the hood of twoPhaseEulerFoam. Most of them can be found in H. Rusches thesis, which is great because to me C++ source code is not self explanatory in the case of fluid dynamics. I have a question about the turbulence model. In H. Rusches thesis (page 105, eq. 3.14 and 3.15) the k-equation reads as follows (forgive the LaTeX syntax) \frac{\partial k_b}{\partial t} + (U_b \cdot \nabla) k_b - and so on ... but the source code in kEpsilon.H is: Code: fvm::ddt(beta, k) + fvm::div(phib, k) + and so on ... what I would translate into \frac{\partial \beta k_b}{\partial t} + \nabla \cdot (U_b k_b) - and so on ... The same is also the case for the epsilon equation. Also the right hand side of both equations seem to have been multiplied by beta. Code: ... == beta*G - fvm::Sp(beta*epsilon/k, k) Does anyone know what is the reason for this? Last edited by GerhardHolzinger; May 25, 2012 at 07:51. Reason: added page and equation numbers

May 25, 2012, 12:12
#2
New Member

Qingang Xiong
Join Date: May 2012
Location: Ames, IA, USA
Posts: 20
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Quote:
 Originally Posted by GerhardHolzinger Hello, I am trying to find out which equations are under the hood of twoPhaseEulerFoam. Most of them can be found in H. Rusches thesis, which is great because to me C++ source code is not self explanatory in the case of fluid dynamics. I have a question about the turbulence model. In H. Rusches thesis (page 105, eq. 3.14 and 3.15) the k-equation reads as follows (forgive the LaTeX syntax) \frac{\partial k_b}{\partial t} + (U_b \cdot \nabla) k_b - and so on ... but the source code in kEpsilon.H is: Code: fvm::ddt(beta, k) + fvm::div(phib, k) + and so on ... what I would translate into \frac{\partial \beta k_b}{\partial t} + \nabla \cdot (U_b k_b) - and so on ... The same is also the case for the epsilon equation. Also the right hand side of both equations seem to have been multiplied by beta. Code: ... == beta*G - fvm::Sp(beta*epsilon/k, k) Does anyone know what is the reason for this?
Hi GerhardHolzinger,
I also found this difference in twoPhaseEulerFoam. But when I run the code, it seems that no problem. May be you can modify it to standard k-e. Good luck!

October 16, 2012, 02:25
#3
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Dongyue Li
Join Date: Jun 2012
Location: Beijing, China
Posts: 794
Rep Power: 15
Quote:
 Originally Posted by GerhardHolzinger Hello, I am trying to find out which equations are under the hood of twoPhaseEulerFoam. Most of them can be found in H. Rusches thesis, which is great because to me C++ source code is not self explanatory in the case of fluid dynamics. I have a question about the turbulence model. In H. Rusches thesis (page 105, eq. 3.14 and 3.15) the k-equation reads as follows (forgive the LaTeX syntax) \frac{\partial k_b}{\partial t} + (U_b \cdot \nabla) k_b - and so on ... but the source code in kEpsilon.H is: Code: fvm::ddt(beta, k) + fvm::div(phib, k) + and so on ... what I would translate into \frac{\partial \beta k_b}{\partial t} + \nabla \cdot (U_b k_b) - and so on ... The same is also the case for the epsilon equation. Also the right hand side of both equations seem to have been multiplied by beta. Code: ... == beta*G - fvm::Sp(beta*epsilon/k, k) Does anyone know what is the reason for this?
hi , do u know where can I get H. Rusches thesis? or the full name?

 October 16, 2012, 03:59 #4 Senior Member   Gerhard Holzinger Join Date: Feb 2012 Location: Austria Posts: 316 Rep Power: 26 Hello, you can find H. Rusches thesis amongst others at this page: http://www.foamcfd.org/resources/theses.html

October 16, 2012, 04:03
#5
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Dongyue Li
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Quote:
 Originally Posted by GerhardHolzinger Hello, you can find H. Rusches thesis amongst others at this page: http://www.foamcfd.org/resources/theses.html
thanks! you are online.

by the way, can u recommend me some papers about twophaseeulerfoam?

some of the parameters I dont know the exact mean.

 October 16, 2012, 04:25 #6 Senior Member   Gerhard Holzinger Join Date: Feb 2012 Location: Austria Posts: 316 Rep Power: 26 I haven't really found any research papers dealing with the basics of twoPhaseEulerFoam. H. Rusches thesis is a good point to start digging into the solver. Also the article about bubbleFoam in the OpenFOAM Wiki helps to understand the solver http://openfoamwiki.net/index.php/BubbleFoam

October 16, 2012, 04:28
#7
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Dongyue Li
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Quote:
 Originally Posted by GerhardHolzinger I haven't really found any research papers dealing with the basics of twoPhaseEulerFoam. H. Rusches thesis is a good point to start digging into the solver. Also the article about bubbleFoam in the OpenFOAM Wiki helps to understand the solver http://openfoamwiki.net/index.php/BubbleFoam
Okay, thank you very much! that would do me alot of favor

 Tags turbulence, two-phase, twophaseeulerfoam