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-   -   3 boundary conditions at a time on a single wall surface (http://www.cfd-online.com/Forums/fluent/105635-3-boundary-conditions-time-single-wall-surface.html)

 n7310889 August 4, 2012 18:26

3 boundary conditions at a time on a single wall surface

Hi,
I'm simulating a steady state 3D conjugate heat transfer problem of a parabolic trough concentrating collector receiver. Here receiver is simply a annular tube (consists of a large tube with a smaller concentric cylinder inserted) through which syltherm oil is passing to collect the heat energy.

The receiver gets concentrated radiation (which is reflected from a parabolic trough mirror). This radiation creates transversely a high non uniform heat source (or may be heat flux) around the tube. A portion of this radiation is absorbed by the oil, and the rest is lost due to radiation and probably convection from the tube surface.The boundary condition for the heat source might be an UDF defining a function for heat source/heat flux around the tube, and will make sure that the heat flux is non-uniform according to the reflected radiation profile.

Now, I'm wondering:confused: how can I accommodate these THREE boundary conditions on a single surface:1. a function defining a non-uniform heat flux, 2. radiation loss and 3. convection loss. Someone proposed me to give SOURCE TERM, instead of heat flux, and activate "MIXED" option (that is both radiation and convection option) from the drop down list of the boundary condition for the wall surface. But, this source term should provide a uniform heat energy around the tube body instead of a non-uniform heat flux, shouldn't it?

Could any of you please suggest me how can I accommodate all of these three boundary conditions on a single wall surface?

 n7310889 August 12, 2012 20:10

It seems no body knows how to solve the problem!!!!!!!!!!!

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