Solar radiation incident on a boundary plus convection

[matt_s]

Hi

I am looking at a problem where I would like to have radiation incident on a boundary equivalent to the effects of the sun i.e. 1kW/m^2 and also have convection losses to the surroundings. There is also some conduction into the body of the material. I can't see how to use the external temperature and heat coefficient to incorporate the convection part. However, I can't see how to include radiation of a set value. Do I need to include another body in my simulation with an appropriate temperature to create the radiation effects of the sun?

Thanks

Matt

[raback]

Hi

If you're radiating to space it is sufficient to specify the external temperature. Often you cannot make this approximation and then the view factors need to computed between different radiating boundaries. Generally speaking this must be done for non-convex objects.

-Peter

[matt_s]

Thanks for your reply. I am not sure I made myself very clear in my question. The problem I am looking at involves an insulated tank. the contents of the tank are warmer than their surroundings and therefore it will cool slowly over time. However there is the additional complication of radiation from the sun during the daytime. I am struggling with the boundary condition on the outside of the insulation layer of the tank. I have effectively got the usual convection losses defined by the ambient temp ( say 300k) and heat transfer coefficient of about 10w/m2/K. However I don't know how to incorporate this extra heat input at the boundary of 1kW/m2 from the sun. The geometry of the problem is not that important so even if I could add a permenant background input of 1kw/m2 that would be fine.

[jeroenr]

The keyword to search for is "heat flux". You can find it in the Elmer Models Manual or on this forum:

viewtopic.php?f=3&t=3362
viewtopic.php?f=7&t=3262

That, combined with the last thing you said.