thermal non-equilibrium

m5m5kh · October 3, 2013, 14:27

HI foamers
I run my case in a thermal equilibrium condition for a porous media with porousSimpleFoam
I want to consider non thermal equilibrium and write a thermal equation for solid phase and fluid phase.is it possible?
what should I do?

the equation added in file

any help would be appreciated

best regards
Mohsen

klilla · October 7, 2013, 02:40

Dear Mohsen,

you have at least 2 choices depending on your problem.

1. You can stay with porousSimplefoam. Here the porosity is actually handled as a momentum sink. Now, your non-equilibrium means, I guess, that there is heat transfer between your fluid and solid. So you need a heat sink/source in your temperature equation to represent it.

2. Now, if you do not know the form of this heat sink, you have to go for conjugate heat transfer. This way is a bit more difficult, since there is no incompressible cht solver in openfoam. So you have to change the fluid solver in chtMultiRegionSimpleFoam. Then you can have your desired equations to be solved.

Best,
Lilla

m5m5kh · October 18, 2013, 14:51

hi Killa
would you please describe it to me step by step. I am not as professional as you in OF.

regards
Mohsen

Quote:

Originally Posted by klilla

Dear Mohsen,

you have at least 2 choices depending on your problem.

1. You can stay with porousSimplefoam. Here the porosity is actually handled as a momentum sink. Now, your non-equilibrium means, I guess, that there is heat transfer between your fluid and solid. So you need a heat sink/source in your temperature equation to represent it.

2. Now, if you do not know the form of this heat sink, you have to go for conjugate heat transfer. This way is a bit more difficult, since there is no incompressible cht solver in openfoam. So you have to change the fluid solver in chtMultiRegionSimpleFoam. Then you can have your desired equations to be solved.

Best,
Lilla

klilla · October 25, 2013, 04:42

Dear Mohsen,

I can't give you steps without you deciding what problem you wish to solve. As I wrote, you have 2 choices depending your problem. And the choice you need to take depends on physical considerations not how professional you are in OF.
Best,
Lilla

Daniel_P · January 17, 2014, 10:30

Hello!

I am also trying to model porous media in OpenFOAM and am facing the same problem as Mohen. I would like to model thermal non-equilibrium and consequently two energy equations have to be solved, one for the fluid and one for the solid. The two temperatures T_f and T_s are connected by the volumetric heat transfer h_v.
I do not want to mesh the porous media itself (e.g. the particle bed) and then perform a conjugated heat transfer simulation but hope to find a way of modelling the porous medium as one integral block.

I am new to OpenFOAM but as far as I understand the porous solvers that are implemented only consider the porosity by adding a source term in the momentum equation. There is no consideration of the porosity in the energy equation, right?
As Lilla wrote, it should be possible to consider the heat exchange between solid and fluid by heat sources in the energy equation. However, by doing this I only solve the energy equation for the fluid and not for the solid. I would have to give the temperature of the solid as a direct or "indirect" input variable (example for "indirect" input: defining a heat flow from the solid to the fluid).

I also want to solve the energy equation of the solid and hence include heat conduction in the solid. Since there will be an energy exchange between fluid and solid this corresponds to a conjugated problem.

Can you imagine a way of calculating this conjugated problem without resolving the porous structure (e.g. the particle bed) in the mesh?
Maybe it would be possible to define the porosity block in a way that it is fluid and solid at the same time. Both energy equations (for solid and fluid) could be solved consecutively for this region of the mesh. What do you think?

Best regards,
Daniel

cdegroot · January 20, 2014, 13:26

I have done extensive research into solving non-equilibrium energy equations in porous media. You will find that you get much nicer convergence if you solve the two energy equations as a coupled set. I have written a paper about a method I developed for my own finite volume code. You can download here http://dx.doi.org/10.1080/10407790.2011.601180. Send me a message if you can't access that link and I can provide you with a copy. Perhaps you will be able to apply this method in OpenFOAM. I have been considering doing so myself, but I have not had much time to look into it.

Daniel_P · January 21, 2014, 01:49

Your work looks very interesting, thank you very much for the reference!
I will work through the report in the coming days...

mmunige · July 13, 2016, 08:56

Dear all,

I am modelling heat transfer in porous medium (from hot air to porous medium) in Fluent. I have defined non-equilibrium thermal model in 'porous zone' in cell zone conditions (type: fluid). Fluent have created co-incident (shadow) solid zone adjacent to the fluid zone. and for that solid zone i have defined fixed temperature (fixed value).
Other settings for porous medium like resistance coeffecients have been defined as usual.
But
I am not sure is this all we need to do to define non-equillibrium thermal model??
in result analysis I have to check solid temperature at different points along the height of column. But i dont know how to get this display? currently i have created some points by point creation in my geometry but i think it displays fluid or solid-fluid mean temperature, not the solid temperature that i need.

Please help me on these problems.

Thank you very much.
Regards

Adri_12 · February 1, 2018, 06:01

Hi Foamers,

Someone could tell me what is the state of art in OpenFoam considering heat exchanges in pourous media with a non-equilibrium model ?

That is to say that the fluid & the solid are modeled as 2 independent parts (2 different thermal equations & 2 meshing) and we resolve 2 conservation laws and one heat transfer between both of them.

Thanks for the reply I'm really wondering if that exists in OpenFoam.

Adrià

svramana · February 15, 2018, 07:55

Quote:

Originally Posted by m5m5kh

HI foamers
I run my case in a thermal equilibrium condition for a porous media with porousSimpleFoam
I want to consider non thermal equilibrium and write a thermal equation for solid phase and fluid phase.is it possible?
what should I do?

the equation added in file

any help would be appreciated

best regards
Mohsen

Hello Mohsen,
Can yiou share your PoroussimpleFoam solver and case file which has TEqn inplimemted intoit.i am struggling to add Temp. equation to porous simplefoam.

Regards,
S.V.Ramana

Adri_12 · February 15, 2018, 10:08

Quote:

Originally Posted by klilla

Dear Mohsen,

you have at least 2 choices depending on your problem.

1. You can stay with porousSimplefoam. Here the porosity is actually handled as a momentum sink. Now, your non-equilibrium means, I guess, that there is heat transfer between your fluid and solid. So you need a heat sink/source in your temperature equation to represent it.

2. Now, if you do not know the form of this heat sink, you have to go for conjugate heat transfer. This way is a bit more difficult, since there is no incompressible cht solver in openfoam. So you have to change the fluid solver in chtMultiRegionSimpleFoam. Then you can have your desired equations to be solved.

Best,
Lilla

Dear Lilla,

I have the intention of modelize a thermal energy storage by using a 3 region system, air/porous/air, and your 1. approach, considering heat transfer between your fluid and solid, is the one I would like to use to modelize with openfoam. Hier some little practical questions:

- Do you think that it is possible to do that with the porousSimpleFoam solver
- From which tutorial do you think I can start my case?
- Do you think that I have to modify the solvers a lot, do you have any advice to do that? (step by step procedures...)

Thank you very much for your help.

Adrià

Adri_12 · February 16, 2018, 11:31

Hi Ramana,

Quote:

Originally Posted by svramana

Hello Mohsen,
Can yiou share your PoroussimpleFoam solver and case file which has TEqn inplimemted intoit.i am struggling to add Temp. equation to porous simplefoam.

Regards,
S.V.Ramana

Why do you prefer to stay with PorousSimpleFoam solver instead of using chtMultiRegionSimpleFoam with integration of porous zone ?

I am wondering what is the best solution when considering heat transfers with fluid/porous region/fluid flow.

Thanks for your help and good luck !

Adrià

svramana · February 16, 2018, 11:41

Quote:

Originally Posted by Adri_12

Hi Ramana,

Why do you prefer to stay with PorousSimpleFoam solver instead of using chtMultiRegionSimpleFoam with integration of porous zone ?

I am wondering what is the best solution when considering heat transfers with fluid/porous region/fluid flow.

Thanks for your help and good luck !

Adrià

i want to do the simulation using single domain approach.(single set of equations utilized for solving both porous and fluid zones).moreover i am new to OF
My simulation domaincfd domain.png
Governing EqnsGEqn.png

Best regards,

Adri_12 · February 19, 2018, 09:19

Quote:

Originally Posted by svramana

i want to do the simulation using single domain approach.(single set of equations utilized for solving both porous and fluid zones).moreover i am new to OF
My simulation domainAttachment 61419
Governing EqnsAttachment 61420

Best regards,

Hi Ramana,

Have you seen this report : https://www.politesi.polimi.it/bitst..._DiStefano.pdf

It is maybe what you need ? In my case, I am looking for a thermal non equilibrium problem. That is why I think that it would be better to start from the chtMultiRegion solvers.

adri

PRATBHARAT · November 13, 2019, 14:59

Quote:

Originally Posted by cdegroot

I have done extensive research into solving non-equilibrium energy equations in porous media. You will find that you get much nicer convergence if you solve the two energy equations as a coupled set. I have written a paper about a method I developed for my own finite volume code. You can download here http://dx.doi.org/10.1080/10407790.2011.601180. Send me a message if you can't access that link and I can provide you with a copy. Perhaps you will be able to apply this method in OpenFOAM. I have been considering doing so myself, but I have not had much time to look into it.

I an unable to access it.

January 20, 2014, 13:26		#6
cdegroot Senior Member Chris DeGroot Join Date: Nov 2011 Location: Canada Posts: 414 Rep Power: 17	I have done extensive research into solving non-equilibrium energy equations in porous media. You will find that you get much nicer convergence if you solve the two energy equations as a coupled set. I have written a paper about a method I developed for my own finite volume code. You can download here http://dx.doi.org/10.1080/10407790.2011.601180. Send me a message if you can't access that link and I can provide you with a copy. Perhaps you will be able to apply this method in OpenFOAM. I have been considering doing so myself, but I have not had much time to look into it. fuzzylogic likes this.

July 13, 2016, 08:56	Non-equilibrium thermal model for porous medium	#8
mmunige New Member mm Join Date: May 2016 Posts: 24 Rep Power: 8	Dear all, I am modelling heat transfer in porous medium (from hot air to porous medium) in Fluent. I have defined non-equilibrium thermal model in 'porous zone' in cell zone conditions (type: fluid). Fluent have created co-incident (shadow) solid zone adjacent to the fluid zone. and for that solid zone i have defined fixed temperature (fixed value). Other settings for porous medium like resistance coeffecients have been defined as usual. But I am not sure is this all we need to do to define non-equillibrium thermal model?? in result analysis I have to check solid temperature at different points along the height of column. But i dont know how to get this display? currently i have created some points by point creation in my geometry but i think it displays fluid or solid-fluid mean temperature, not the solid temperature that i need. Please help me on these problems. Thank you very much. Regards

February 1, 2018, 06:01	OpenFoam State of developpement of non-equilibrium in porous media	#9
Adri_12 New Member Adri Join Date: Sep 2017 Posts: 24 Rep Power: 8	Hi Foamers, Someone could tell me what is the state of art in OpenFoam considering heat exchanges in pourous media with a non-equilibrium model ? That is to say that the fluid & the solid are modeled as 2 independent parts (2 different thermal equations & 2 meshing) and we resolve 2 conservation laws and one heat transfer between both of them. Thanks for the reply I'm really wondering if that exists in OpenFoam. Adrià

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October 7, 2013, 02:40		#2
klilla Member Kapa Lilla Join Date: Mar 2009 Location: Bruxelles, Belgium Posts: 57 Rep Power: 17	Dear Mohsen, you have at least 2 choices depending on your problem. 1. You can stay with porousSimplefoam. Here the porosity is actually handled as a momentum sink. Now, your non-equilibrium means, I guess, that there is heat transfer between your fluid and solid. So you need a heat sink/source in your temperature equation to represent it. 2. Now, if you do not know the form of this heat sink, you have to go for conjugate heat transfer. This way is a bit more difficult, since there is no incompressible cht solver in openfoam. So you have to change the fluid solver in chtMultiRegionSimpleFoam. Then you can have your desired equations to be solved. Best, Lilla

October 25, 2013, 04:42		#4
klilla Member Kapa Lilla Join Date: Mar 2009 Location: Bruxelles, Belgium Posts: 57 Rep Power: 17	Dear Mohsen, I can't give you steps without you deciding what problem you wish to solve. As I wrote, you have 2 choices depending your problem. And the choice you need to take depends on physical considerations not how professional you are in OF. Best, Lilla

January 17, 2014, 10:30		#5
Daniel_P New Member Join Date: Dec 2013 Posts: 11 Rep Power: 12	Hello! I am also trying to model porous media in OpenFOAM and am facing the same problem as Mohen. I would like to model thermal non-equilibrium and consequently two energy equations have to be solved, one for the fluid and one for the solid. The two temperatures T_f and T_s are connected by the volumetric heat transfer h_v. I do not want to mesh the porous media itself (e.g. the particle bed) and then perform a conjugated heat transfer simulation but hope to find a way of modelling the porous medium as one integral block. I am new to OpenFOAM but as far as I understand the porous solvers that are implemented only consider the porosity by adding a source term in the momentum equation. There is no consideration of the porosity in the energy equation, right? As Lilla wrote, it should be possible to consider the heat exchange between solid and fluid by heat sources in the energy equation. However, by doing this I only solve the energy equation for the fluid and not for the solid. I would have to give the temperature of the solid as a direct or "indirect" input variable (example for "indirect" input: defining a heat flow from the solid to the fluid). I also want to solve the energy equation of the solid and hence include heat conduction in the solid. Since there will be an energy exchange between fluid and solid this corresponds to a conjugated problem. Can you imagine a way of calculating this conjugated problem without resolving the porous structure (e.g. the particle bed) in the mesh? Maybe it would be possible to define the porosity block in a way that it is fluid and solid at the same time. Both energy equations (for solid and fluid) could be solved consecutively for this region of the mesh. What do you think? Best regards, Daniel

January 21, 2014, 01:49		#7
Daniel_P New Member Join Date: Dec 2013 Posts: 11 Rep Power: 12	Your work looks very interesting, thank you very much for the reference! I will work through the report in the coming days...