CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   conjugate heat transfer boundary condition (http://www.cfd-online.com/Forums/fluent/77065-conjugate-heat-transfer-boundary-condition.html)

 Souviktor June 11, 2010 10:52

conjugate heat transfer boundary condition

Hi all,

I am simulating a conjugate heat conduction problem in which a fluid is inside a glass tube having very large wall thickness.So I want to study the conduction through the wall as well as through the fluid.
So I have created an axisymmetric model in gambit.Now,the problem is setting of boundary condition for the internal surface of the glass tube.This surface is in contact with the fluid as well as the glass tube.

If I set it as wall what should be the thermal b.c at this wall?
If I set it as interface there is initialization error in fluent,

The heat flux is applied at the outer boundary of the tube.
If I apply wall b.c at the internal tube wall, then the heat does not conduct to the fluid as the default b.c in fluent is adiabatic wall b.c.

 CFDtoy June 11, 2010 15:54

bc for conjugate

there is a bc called "coupled" bc - if there are 2 fluids on either side of the wall, you can use this condition and input wall thickness and material property (for resistance calculation) - this will serve to transmit data across different fluid regions.

fluent manual gives a very good explanation on how to do this.

Thanks,

/CFDtoy

Quote:
 Originally Posted by Souviktor (Post 262644) Hi all, I am simulating a conjugate heat conduction problem in which a fluid is inside a glass tube having very large wall thickness.So I want to study the conduction through the wall as well as through the fluid. So I have created an axisymmetric model in gambit.Now,the problem is setting of boundary condition for the internal surface of the glass tube.This surface is in contact with the fluid as well as the glass tube. If I set it as wall what should be the thermal b.c at this wall? If I set it as interface there is initialization error in fluent, The heat flux is applied at the outer boundary of the tube. If I apply wall b.c at the internal tube wall, then the heat does not conduct to the fluid as the default b.c in fluent is adiabatic wall b.c. I am confused.can anyone please help?

 chinc July 3, 2010 00:31

Coupled thermal Boundary Condition

I have created a 3 Dimensional two fluid zone (fluid-solid) with one of the two of the faces coupled to each of the fluid zone. When I read the mesh file, Fluent separate the coupled face into its "shadowed face". However, I did not manage to see the "couple" option under the wall zone during the setting of boundary condition. I am wondering what could be wrong with my setting.

 CFDtoy July 7, 2010 14:26

conjugate

did you check wall -> thermal boundary condition?

if you have a shadow wall..you will definitely see thermal coupled boundary condition. please check.

Quote:
 Originally Posted by chinc (Post 265557) I have created a 3 Dimensional two fluid zone (fluid-solid) with one of the two of the faces coupled to each of the fluid zone. When I read the mesh file, Fluent separate the coupled face into its "shadowed face". However, I did not manage to see the "couple" option under the wall zone during the setting of boundary condition. I am wondering what could be wrong with my setting. Appreciate if you could provide some advice. Many thanks in advance.

 saksham.pachar January 5, 2012 11:25

Hi

I have a flow condition.

http://www.cfd-online.com/Forums/ans...flow-duct.html

as I want to define the bottom of the fin at constant wall temp of 400 k.

but all the adjacent walls are also coming at 400K.

For a fin, In forced convection the temp should decrease , which is not happening.

 thermal energy March 13, 2014 10:23

hello cfdtoy,

ı have a question about coupled boundry condition. ı need help. thank you. good work.

Should i activate coupled option for both wall and wall-shadow, for each side of the two-sided wall?

 magicalmarshmallow April 6, 2014 17:34

Interface resistance units

Hi guys,

I'm a little confused about the units FLUENT requires. I am modelling conjugate heat transfer from a heated body, through an interface material to a fluid. Essentially I have a scenario of

Al block - Interface material - Cu pipe - Water
I have set up so that the interfaces between the materials are 'wall' and I have a 'wall-shadow' in all cases. Given water wets the surface of copper, I'm assume there is a negligible inter-facial resistance there. Application of a 0 m wall thickness gives a result which is nowhere near the experimental value.

So the Gap filler data sheet has a spec which reads

Thermal Resistance °C-Inē/W - 0.015

However, this unit doesn't seem to appear in FLUENT, so how do I convert this to "m", which is what FLUENT wants for the boundary layer thickness.

Does anyone have any experience of this. I'm guessing I'm missing a boat somewhere along the line