CFD Online Discussion Forums

CFD Online Discussion Forums (
-   FLUENT (
-   -   free surface heat transfer! (

NR May 5, 2004 03:56

free surface heat transfer!
Hi,everyone! sorry for distrub you! I am a new fluent user, now I have a difficlut problem to solve by Fluent. My task is to simulate the process of a heat-exchanger, inside the heat exchanger flowing the refrigerating medium where the temperature is very low, and outside the heat exchanger, the air flow across it ,and it temperture is relatively high. So when the external of the heat-exchanger surface temperature is lower than the air dew-point, there must be some water condensation on the surface, and this may be add a heat resistance, so the heat transfer take place on the free surface of the condensation water, until the it is steady. My question is can fluent simulate the process. For I am not very farmilar with Fluent, I have tried some models for it, but none is very approporiate for it. I need you give me some suggestion! Thanks a million!

George May 5, 2004 07:58

Re: free surface heat transfer!
This is really a difficult problem and I'm afraid you cannot solve it in a full detail. You would have to take into account formation of drops, film, etc, if the surfaces are not horizontal, it is far beyond the capabilities of the present general-purpose CFD codes.

What you may do is to try and find some correlations in the literature for the change in heat transfer coefficient as the tubes get wet. This coefficient you may then use in your simulation. Of course you need to solve this as a steady problem, or a sequence of such solutions.

maziar May 5, 2004 10:32

VOF and free surface
Hi everyone,I need to some information about VOF and current research about it and CFD+VOF in multiphase flow.Also,do fluent software include VOF and free surface flow?thanks be happy in your dynamic life

maziar May 5, 2004 10:37

VOF and free surface flow
Hi everyone,I need to some information about VOF and CFD+VOF and current research about them,and another titles about VOF and free surface flow. do fluent software include free surface flow and vof? be happy in dynamic life .

NR May 5, 2004 11:48

Re: free surface heat transfer!
Thanks! Another question: if I add a source such as mass source , monentum source etc, in the interaction surface or free surface, and this sources should add at position of the free surface using UDF, but how can I got the parameters such as temperature, position, and so on on the free surface cell, for I want simulation the unsteady process. Can Fluent deal with it? Thanks for your help! regards!

thomas May 6, 2004 05:35

Re: free surface heat transfer!
Hello, The free surface cross all the cell where the volume fraction is different from 0 or 1. So check the cells of your domain and everywhere 0<C_VOF(c,t)<1, it means that the cell c is cross by the interface.

Hope this help. Thomas

All times are GMT -4. The time now is 15:27.