Add a mass source/sink to simpleFoam

palarcon · March 13, 2019, 07:56

Hello everybody

I want to add a mass source/sink term to the simpleFoam solver, but I fear that it will need more modifications than I would expect.
In summary, what I want to code is the following system:

$\nabla\cdot U =$ S
$U\cdot \nabla U = - \nabla p + \nabla \cdot \nu(\nabla U + \nabla U^T)$

Given the fact that $\nabla\cdot U$ is no longer equal to 0, I assume that in addition to the pressure equation, the stress computation will be also affected, meaning that adding that source term is not as easy as adding a constant to the continuity equation.

My question is, is there any way of adding that source term into simpleFoam, without going into deep modification of additional functions like devDivReff or others?

I was looking and I found that using fvOption could be an option to add a source term without modifying the solver, but it will add a source term to the momentum equation, not to the continuity equation.

Z.Q. Niu · May 13, 2019, 09:50

Hi Pablo,
Have u got it? Thanks!

mAlletto · May 14, 2019, 11:58

in the solver firefoam there is mass source term included. it has to be added in the pressure equation.

you can have a look https://openfoamwiki.net/index.php/FireFoam where the principle is explained a bit.

palarcon · May 15, 2019, 02:31

Quote:

Originally Posted by Z.Q. Niu

Hi Pablo,
Have u got it? Thanks!

Hi.
Yes, I did, but not in a "simple way" like I was looking for. I developed all the equations by hand starting from the transport equations and then I add the necessary terms to the mass equation and the momentum equation.
After that, I just wrote on the code the resultant equations.

palarcon · May 15, 2019, 02:33

Quote:

Originally Posted by mAlletto

in the solver firefoam there is mass source term included. it has to be added in the pressure equation.

you can have a look https://openfoamwiki.net/index.php/FireFoam where the principle is explained a bit.

Thank you for the tip, I will have a look and compare to what did I do.

Pablo

March 13, 2019, 07:56	Add a mass source/sink to simpleFoam	#1
palarcon Member Pablo Alarcón Join Date: Mar 2018 Location: Liège Posts: 59 Rep Power: 9	Hello everybody I want to add a mass source/sink term to the simpleFoam solver, but I fear that it will need more modifications than I would expect. In summary, what I want to code is the following system: $\nabla\cdot U =$ S $U\cdot \nabla U = - \nabla p + \nabla \cdot \nu(\nabla U + \nabla U^T)$ Given the fact that $\nabla\cdot U$ is no longer equal to 0, I assume that in addition to the pressure equation, the stress computation will be also affected, meaning that adding that source term is not as easy as adding a constant to the continuity equation. My question is, is there any way of adding that source term into simpleFoam, without going into deep modification of additional functions like devDivReff or others? I was looking and I found that using fvOption could be an option to add a source term without modifying the solver, but it will add a source term to the momentum equation, not to the continuity equation. Kummi likes this. Last edited by palarcon; March 14, 2019 at 02:58.

May 14, 2019, 11:58		#3
mAlletto Senior Member Michael Alletto Join Date: Jun 2018 Location: Bremen Posts: 616 Rep Power: 16	in the solver firefoam there is mass source term included. it has to be added in the pressure equation. you can have a look https://openfoamwiki.net/index.php/FireFoam where the principle is explained a bit. Kummi likes this.

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May 13, 2019, 09:50		#2
Z.Q. Niu Member Niu Join Date: Apr 2014 Posts: 55 Rep Power: 13	Hi Pablo, Have u got it? Thanks!