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jeevan_yadav July 25, 2012 02:47

Heat transfer modeling between two domains
 
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Hi!
I am new to CFX.I am trying to model heat transfer from solid(copper) to fluid(air) domain.
Solid is placed inside circular air duct. I have to model heat transfer from heated solid to fluid domain by assigning heat flux over solid boundary surfaces. At same time i want to analyse the temperature profile in fluid as well as solid domain.

I tried to define physics in CFX-11 with creating two domains(solid and fluid domain) After solving , i observed no heat flow from solid to fluid domain.

How can i solve problem...

monibjel July 25, 2012 03:55

What are your boundary conditions? And how is the contact area between the solid and fluid?

flotus1 July 25, 2012 04:24

You will need to define an interface between the two regions.

jeevan_yadav July 25, 2012 09:34

Hi all!
Thanks for your interest.
I have created velocity inlet and pressure outlet as BC in fluid domain and wall with constant heat flux as BC in solid domain. Also I have activated 'automatic domain interface creation' in CFX.

Still no heat transfer takes from solid to fluid.

keeper July 25, 2012 09:57

try to do it manually and check box with "heat transfer" to define conservative heat flux and it should work

jeevan_yadav July 25, 2012 11:22

Hi keeper!
I created two different tet mesh files for solid and fluid domain in ICEM and import to CFX 11. After creating manual domain interface for solid and fluid domain, i stuck with following error.

2D regions present in solid domain used in fluid domain.

Actually i created two meshes to create domain interface regions in CFX. common faces where Heat Transfer takes place were present in two meshes with different names. Still i get above error

ghorrocks July 25, 2012 18:41

If you say there is a constant heat flux at the solid interface then this is not a coupled solution. Why don't you do one simulation with the fluid domain only with the solid replaced by a constant heat flux, then a second simulation with the solid only with the boundary replaced by a constant flux.

No point running a coupled simulation when the simulation is not actually coupled.

jeevan_yadav July 26, 2012 04:00

Hi glen!
In my case, i require heat transfer coefficients from solid sufrface to air at various locations. Also i want to model internal heat distribution pattern inside solid domain.

ghorrocks July 26, 2012 07:35

Do you know the heat transfer coefficient or do you want the simulation to provide that?

jeevan_yadav July 29, 2012 07:49

I want to get it from simulation

ghorrocks July 29, 2012 07:51

In that case the solid/fluid interface is modelled as a simple solid fluid interface and the solver calculates the heat flux. This is a straight forward CHT (Conjugate heat transfer) simulation. Have you looked at the CHT simulations in the tutorials? There are a few and they show how they are set up.

Shljuki August 1, 2012 21:43

If possible it might be more appropriate to assign volume heat source [W/m3] to the solid?

jeevan_yadav August 2, 2012 01:59

Hi !
In heating coil tut they used volumetric heat flux. In my case i have to define fix temperature on one side of solid domain and want to see the heat transfer in solid domain as well as temperature distribution on solid and fluid domain.
I did it as given in tut but unable to define the constant temp. wall BC in solid domain.
Pl reply how to do it

Shljuki August 2, 2012 02:24

I am not sure that i understand correctly interaction between the solid and fluid in your case. If non of the above suggestions work for you, you might try to decompose your solid and crteate a thin volume at the location of the surface with constant temperature. Than you can assign constant temperarture to all surfaces af that volume (acting as a surface) and volume itself shall be excluded form simulation domain. You will have a thin hole in your solid domain acting as a constan surface temperature.

jeevan_yadav August 3, 2012 11:01

Hi!
In my case, one cube is placed in other cube. Inner cube is solid domain and annular space is fluid domain.
one of the surface out of 6 inner surfaces of inner cube(solid domain) is at constant temperature. and heat is released in surrounding fluid domain and at the same time conducted through solid domain.

ghorrocks August 4, 2012 06:39

This is straight forward - and I wish you had explained this before :)

Then 5 sides of the solid cube is an interface for coupling to the fluid domain, and one face of the solid cube is a wall, which has a specified temperature on both the solid and fluid side. Note that this will actually be two walls on top of each other - one on the fluid side, one on the solid side.


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