# Non-thermal equilibruim model in fluent

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 December 27, 2011, 05:55 Non-thermal equilibruim model in fluent #1 New Member   rohit mukare Join Date: Aug 2011 Location: rourkela Posts: 16 Rep Power: 7 is it possible to use non-thermal equilibrium model in fluent for porous zone... if yes what are the steps involved in it??

 December 27, 2011, 10:09 #2 Senior Member   Andrew Join Date: Mar 2009 Location: Washington, DC Posts: 195 Rep Power: 9 If I remember correctly, yes you can. I believe it was just a option you clicked - maybe where you activate the energy equation

 December 27, 2011, 11:13 #3 New Member   rohit mukare Join Date: Aug 2011 Location: rourkela Posts: 16 Rep Power: 7 yes i have defined the porous zone with viscous and inertial resistance along with porosity bt i dnt knw whr to attach the source term for solid matrix and i defined UDS for that bt still it won't run. i guess i m missing sumthing.if you can help. if you want i cant upload the udf for source term for fluid and solid matrix. bt i dnt knw hw to link it. it will be really helpful if you can help.

 December 27, 2011, 11:17 #4 Senior Member   Andrew Join Date: Mar 2009 Location: Washington, DC Posts: 195 Rep Power: 9 what are you using a UDF for? Fluent will do everything that you need to do regarding porous media.

 December 27, 2011, 11:25 #5 New Member   rohit mukare Join Date: Aug 2011 Location: rourkela Posts: 16 Rep Power: 7 we need to calculate the heat transfer coefficent between the gas and the porous matrix as the temp will nt be same at any instance and there will be heat transfer taking place between them. the udf which i wrote are for source term for solid matrix and for fluid region. as we know we need to solve two enegy equation in this case and fluent solves only one equation. my question is how to incorporate the energy equation for solid matrix in porous zone region in order to run the process...

 December 27, 2011, 11:34 #6 Senior Member   Andrew Join Date: Mar 2009 Location: Washington, DC Posts: 195 Rep Power: 9 You don't need to write a UDF for the non-equilibrium model. Fluent will do that for you. You just have to turn it on. I did a whole dissertation based on this. Are you running an actual lab model too? I did a bench model and used Fluent v's my code to determine which one was better. Fluent wasn't doing the non-equilibrium model when I was doing my research. The way my code worked for the non-equilibrium model was that I solved for the flow field first, and then brought those into the thermal model. I did not couple them. I had problems with the entrance region of the porous media.

 December 27, 2011, 11:39 #7 New Member   rohit mukare Join Date: Aug 2011 Location: rourkela Posts: 16 Rep Power: 7 how do you did that bcoz i hv been reading a lot of research papers whr they did the non-equilibrium model using udf. this is a link to one of that papers...ihope you can help me i m really trying to sove this problem for my masters thesis. http://www.sciencedirect.com/science...59431109002427 i hope this will help you understand my problem

 December 27, 2011, 11:50 #8 Senior Member   Andrew Join Date: Mar 2009 Location: Washington, DC Posts: 195 Rep Power: 9 the best thing I can do is tell you to call Fluent. If you have a 'legal' copy they will help you out. Sometimes it takes a few days, but I have had good experiences with their support.

 December 27, 2011, 12:03 #9 New Member   rohit mukare Join Date: Aug 2011 Location: rourkela Posts: 16 Rep Power: 7 ya i will do that...thanks for you help.

 December 27, 2011, 12:33 #10 Senior Member   Andrew Join Date: Mar 2009 Location: Washington, DC Posts: 195 Rep Power: 9 like I said earlier, I did a dissertation/journal paper based on the thermal non-equilibrium model and a matrix heat exchanger (basically porous media) and found that the TNE model does a better job of replicating the actually data. good luck

 December 27, 2011, 21:59 hi #11 Senior Member   shoeb khan Join Date: Nov 2011 Posts: 179 Rep Power: 6 hi Al ready there are lot of posts and discussion here but i wanna add something to it. Turn off energy equation. Go the porous zone tab in boundary condition and then click on souce and add the source term there. I hope that it will help you.

 December 28, 2011, 01:48 #12 New Member   rohit mukare Join Date: Aug 2011 Location: rourkela Posts: 16 Rep Power: 7 hi bt hw will it calculate the temperature if i disable the energy equation. as the inlet to porous zone is at high temp and as it passes through the porous zone it temp gets reduced so hw will you exactly do that??

 December 29, 2011, 10:23 #13 Senior Member   shoeb khan Join Date: Nov 2011 Posts: 179 Rep Power: 6 what is the problem that you are facing now.

 December 29, 2011, 11:25 #14 New Member   rohit mukare Join Date: Aug 2011 Location: rourkela Posts: 16 Rep Power: 7 i m doing the analysis of stirling inertance pulse tube refrigerator.in this geometry there is a porous zone which i need to model using local non-equilibruim method. it means that when fluid flows through the porous zone the temperature of fluid And the porous material are different and so heat transfer takes place between them.and as we knw fluent solves only one equation of energy. while i need to solve to separate energy equation one for fluid and the other for solid. i have written the code for solid phsae equation along with source term for solid and fluid bt i dnt knw hw we link the both equation in a single zone.i m using k-e model of turbulence

December 29, 2011, 21:12
#15
Senior Member

shoeb khan
Join Date: Nov 2011
Posts: 179
Rep Power: 6
Quote:
 Originally Posted by rohit.mukare7 i m doing the analysis of stirling inertance pulse tube refrigerator.in this geometry there is a porous zone which i need to model using local non-equilibruim method. it means that when fluid flows through the porous zone the temperature of fluid And the porous material are different and so heat transfer takes place between them.and as we knw fluent solves only one equation of energy. while i need to solve to separate energy equation one for fluid and the other for solid. i have written the code for solid phsae equation along with source term for solid and fluid bt i dnt knw hw we link the both equation in a single zone.i m using k-e model of turbulence
hi
Did you tried to use two different source term in the porous zone.
go to porous tab .click on source. Add two source there and hook your udf there .What is the problem in that case.
And first solve the flow and then add the udf and on the energy equation.

thanks
shk

 December 30, 2011, 00:35 #16 New Member   rohit mukare Join Date: Aug 2011 Location: rourkela Posts: 16 Rep Power: 7 ya i tried that it shows d following error- CAR type invalid pair not match" something like that what does it mean. how do i first solve the flow. it means first i need to do my analysis only for flow and then again do it by selecting energy eqyation from sove equation box.

December 30, 2011, 02:46
#17
Senior Member

shoeb khan
Join Date: Nov 2011
Posts: 179
Rep Power: 6
Quote:
 Originally Posted by rohit.mukare7 ya i tried that it shows d following error- CAR type invalid pair not match" something like that what does it mean. how do i first solve the flow. it means first i need to do my analysis only for flow and then again do it by selecting energy eqyation from sove equation box.
yES TRY TO SOLVE THE PROBLEM LIKE THAT WAY AND THEN SEE WHAT RESULTS COME
SOLVE FLOW FIRST
THEN HOOF TH E UDF INTO THE SOURCE TERM

 October 13, 2014, 02:18 LNTE in flluent 14 #18 New Member   sandy Join Date: Oct 2014 Posts: 4 Rep Power: 4 Hi Guys, Rohit, u can do this in fluent (at-least version i am using )& no need of UDF. i am facing similar problem.When i switch to non-thermal model in "Cell zone " i get a message like " U have to create a solid that is spatially coincident with the fluid body ( porous )" and then only all req fields like "heat transfer coeff (b/w solid and gas) "appears. this totally makes sense that energy eq will be solved for solid and fluid separately. But , in "Boundary Conditions " when u assign the conditions for this solid domain , error message is "Fluid boundary is adjacent to solid body " . Can u help ?? Ozair Piracha likes this.

 October 13, 2014, 09:44 #19 Senior Member   Andrew Join Date: Mar 2009 Location: Washington, DC Posts: 195 Rep Power: 9 it sounds like you have something wrong in your model - not the BCs. Did you join the fluid and solid boundaries so they see each other? fuzzylogic likes this.

 October 15, 2014, 01:22 #20 New Member   sandy Join Date: Oct 2014 Posts: 4 Rep Power: 4 NO , i just made a cuboid , meshed it (project orineted). and then in cell zone defined it as fluid type > porous .etc and then when i try to solve for LNTE model the problem as i told earlier arrived. I am not that much good at Fluent , can u please help me and elaborate your suggestion!

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