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-   -   twoPhaseEulerFoam turbulence model (http://www.cfd-online.com/Forums/openfoam-solving/102224-twophaseeulerfoam-turbulence-model.html)

GerhardHolzinger May 25, 2012 07:50

twoPhaseEulerFoam turbulence model
 
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?

Qingang Xiong May 25, 2012 12:12

Quote:

Originally Posted by GerhardHolzinger (Post 363097)
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!:cool:

sharonyue October 16, 2012 02:25

Quote:

Originally Posted by GerhardHolzinger (Post 363097)
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?

GerhardHolzinger October 16, 2012 03:59

Hello,

you can find H. Rusches thesis amongst others at this page:

http://www.foamcfd.org/resources/theses.html

sharonyue October 16, 2012 04:03

Quote:

Originally Posted by GerhardHolzinger (Post 386815)
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.

GerhardHolzinger October 16, 2012 04:25

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

sharonyue October 16, 2012 04:28

Quote:

Originally Posted by GerhardHolzinger (Post 386821)
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


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