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-   -   laminar flow with heat transfer (http://www.cfd-online.com/Forums/openfoam/120053-laminar-flow-heat-transfer.html)

rajcfd June 29, 2013 10:56

laminar flow with heat transfer
 
Hi everyone,


I have been trying simulate laminar flow with a constant heat flux through a cylindrical pipe. I have tried using buoyantBoussinesqSimpleFoam, buoyantBoussinesqPimpleFoam and even icoFoam with chnages in code. The buoyantSimple case is not converging and the other two cases are also not giving correct answers.

I have used bc T- fixedGradient along wall to incorporate heat flux thing....

Can anyone suggest why the results are not coming correct??
Please, I am stuck with this one for two weeks....I need help..

Thanks in advance....

nimasam June 29, 2013 15:44

what is your fluid?
why dont you use bouyantSimpleFoam?

rajcfd July 2, 2013 02:34

Hi nimasam,

My fluid is water, incompressible case. Also, I need to take into account gravity also. The solver which you are suggesting works for compressible fluids?

nimasam July 2, 2013 03:58

yes, it almost use for compressible fluid, but it can be used for incompressible fluid too ;), if you choose apropriate thermoPhydicalDict

However you choose some how suitable solvers, would you please, share your results in different solvers, and make much more declare why results are not correct

rajcfd July 3, 2013 04:57

Quote:

Originally Posted by nimasam (Post 437240)
yes, it almost use for compressible fluid, but it can be used for incompressible fluid too ;), if you choose apropriate thermoPhydicalDict

However you choose some how suitable solvers, would you please, share your results in different solvers, and make much more declare why results are not correct

I worked with buoyantBoussinesqSimpleFoam solver. I made the beta value zero and used potential foam initially as boundary condition was outflow.
It has worked and I have got similar profiles but the magnitude is not correct.

Like the maximum average velocity should have been 0.002 but it is coming out to be 0.0015 & similarly the expected temperature ranges were 307-338 but it is giving 301-334.
I have checked the bc's. It looks correct to me. So, why it is so?

nimasam July 3, 2013 05:01

its damn close ;), maybe you need to play with ur numerical schemes forexample using second order schemes or refine your mesh

rajcfd July 5, 2013 04:04

Quote:

Originally Posted by nimasam (Post 437498)
its damn close ;), maybe you need to play with ur numerical schemes forexample using second order schemes or refine your mesh

Thanks nimasam... I m working on it.

Umut April 19, 2014 09:25

Hello good foamers,

I'm a new beginner in openfoam. I need to ask 2 questions.
A)I'd like to solve a laminar channel flow in 2D. I'll use air as the working fluid and will use constant heat flux in one boundary. I tried to use buoyantBousinesqSimpleFoam but can't figure out how to arrange case files. Here is what I tried;
1) In RASProperties, I choose turbulence off and laminar as model. I deleted every variables in 0 folder except than p_rgh and copied the p,T,U files from my_icoFoam applications.
2) I used the same BCs for p_rgh as given in the iglooWithFridges tutorial by rearranging them to the geometry which I used.
3) The rest is the same with iglooWithFridges tutorial. I ran blockMesh without error.
When I type buoyantBousinesqSimpleFoam in the terminal an error occurs concerning alphat. So how can I overcome this problem?
B) Is there any standard solver to solve this problem transient?

Kind Regards.
Umut

nimasam April 19, 2014 09:33

Quote:

When I type buoyantBousinesqSimpleFoam in the terminal an error occurs concerning alphat. So how can I overcome this problem?
add alphat to your 0 directory and put the values of all boundaries and internal domain zero

Umut April 19, 2014 09:57

Dear nimasam;

Thank you for your reply, your suggestion worked just fine. I also found that buoyantBousinesqPimpleFoam works for transient flows.
Kind regards,

Umut


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