# Convection heat transfer with unknow stream temperature

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February 21, 2013, 17:52
Convection heat transfer with unknow stream temperature
#1
New Member

Moien Farmahini
Join Date: Feb 2013
Posts: 5
Rep Power: 6
We are try to calculate temperature distribution over a solid surface. We know stream velocity, temperature and heat transfer coefficient at the entrance. However, we need to calculate temperature of the surface.
The surface is not in a constant temperature. Also, we dont know the heat flux.
How do you think we can set up the configuration for the situation here.
Please let us know if you have any idea.

One idea is to assign the UDF file that extract temperature after each iteration and consider that temperature as the free stream temperature. However, we dont know how we can develop such a UDF file!!!
It is idea possible?? if yes, How??
Please let me know if you have any good resources or tutorials.

Thank you.
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 setup-post.jpg (19.8 KB, 21 views)

February 22, 2013, 10:50
#2
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François Grégoire
Join Date: Jan 2010
Posts: 389
Rep Power: 10
Some stuff is not clear in your model, see picture.
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 setup-post.jpg (57.1 KB, 20 views)

February 22, 2013, 11:36
#3
New Member

Moien Farmahini
Join Date: Feb 2013
Posts: 5
Rep Power: 6
Hi,

Thank you for the post.
1- Solid part are not modeled or simulated.
2- Boundary condition at very low is antisymmetric.
3- boundary condition at right side is a wall or dead end. in fact, fluid circulates back.
Model is 3D but a 2d image is shown here.
Input is on the very left side.
See the attached image.
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 setup-post2.jpg (21.8 KB, 7 views)

February 22, 2013, 11:49
#4
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François Grégoire
Join Date: Jan 2010
Posts: 389
Rep Power: 10
- I guess the green solid block is modeled?

- Transient simulation? just give initial temperature to your green solid and Fluent will do the rest for you (then it's your job to go read the theory guide in order to know how Fluent calculates the heat transfer coefficient, etc.).

- In short, just specify initial and boundary conditions and Fluent should give you an answer. No need to develop a complex UDF for heat transfer coefficient unless you want to use some fancy equation of your own.

- I wonder how Fluent will react since there is no outlet? backflow at the inlet? never done that. Maybe someone else could advise on that.
Attached Images
 setup-post.jpg (52.7 KB, 7 views)

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