|
[Sponsors] |
heat transfer with s2s radiation model in fluent |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
July 23, 2008, 11:50 |
heat transfer with s2s radiation model in fluent
|
#1 |
Guest
Posts: n/a
|
Hi,
Recently I am running a model to study the heat transfer effect. The model is a hot object in a room. The B.C. for the hot object is fixed temperature, the B.C. for the room surfaces is 0 heat-flux. The s2s radiation model is on. After I got the result, I found the convection heat transfer is extremely high. The wall.-func.-heat-trans.-coeff. is couple of hundreds at many surfaces. If I turn off the rad model, the wall.-func.-heat-trans.-coeff. is back to normal (10~100). Could anybody tell me what's the reason that the wall.-func.-heat-trans.-coeff becomes so high after the radiation model is on? Thanks very much. D. L. |
|
July 28, 2008, 04:01 |
Re: heat transfer with s2s radiation model in flue
|
#2 |
Guest
Posts: n/a
|
Hi!
I am modelling a production hall with hot mashines in it, I think the problem is comparable to yours. But I use a heat-flux B.C. for the machines. What I found out is that without using a radiation model, the surface temperatures of the machines are much higher than with using radiation. So if you use a fixed temperature B.C., the heat flux with radiation will be much higher than without radiation, which results in a higher heat transfer coefficient. Have you tried other radiation models than s2s? |
|
July 29, 2008, 17:10 |
Re: heat transfer with s2s radiation model in flue
|
#3 |
Guest
Posts: n/a
|
The variable "wall func. heat trans. coeff." depends on T*, a dimensionless temperature. T* depends of the heat flux at the wall. Look at the equations in the user guide, you should find an answer to your question. For my version (6.3.26) the variable "wall func. heat trans. coeff." is define here: "30.4 Alphabetical Listing of Field Variables and Their Definitions" and T* is define here: "12.10.2 Standard Wall Functions"
|
|
July 31, 2008, 07:40 |
Re: heat transfer with s2s radiation model in flue
|
#4 |
Guest
Posts: n/a
|
check the reference values (i suffered from same problem but with some other context)(and i hope you have calculated you are calculating/reading shape factors) your case looks to be natural convection the value 10-100 itself is objectionable
research scholar ashish |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
radiation heat transfer | CFD_student | FLUENT | 1 | May 2, 2007 09:46 |
radiation heat transfer | hadi | FLUENT | 1 | September 22, 2004 05:04 |
Radiation heat transfer | mehdi | Main CFD Forum | 0 | July 1, 2003 08:10 |
Radiation Heat Transfer | The IFRF Heat Transfer Team | Main CFD Forum | 0 | January 31, 2000 14:02 |
Heat Transfer with Radiation | I.Dotsikas | Main CFD Forum | 6 | April 16, 1999 12:06 |