twoPhaseEulerFoam turbulence model

GerhardHolzinger · May 25, 2012, 08:50

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, 13:12

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!

sharonyue · October 16, 2012, 03:25

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?

GerhardHolzinger · October 16, 2012, 04:59

Hello,

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

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

sharonyue · October 16, 2012, 05:03

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.

GerhardHolzinger · October 16, 2012, 05:25

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, 05:28

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

May 25, 2012, 08:50	twoPhaseEulerFoam turbulence model	#1
GerhardHolzinger Senior Member Gerhard Holzinger Join Date: Feb 2012 Location: Austria Posts: 342 Rep Power: 28	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: ... == betaG - fvm::Sp(betaepsilon/k, k) Does anyone know what is the reason for this? Last edited by GerhardHolzinger; May 25, 2012 at 08:51. Reason: added page and equation numbers

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October 16, 2012, 04:59		#4
GerhardHolzinger Senior Member Gerhard Holzinger Join Date: Feb 2012 Location: Austria Posts: 342 Rep Power: 28	Hello, you can find H. Rusches thesis amongst others at this page: http://www.foamcfd.org/resources/theses.html

October 16, 2012, 05:25		#6
GerhardHolzinger Senior Member Gerhard Holzinger Join Date: Feb 2012 Location: Austria Posts: 342 Rep Power: 28	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