[andrew.saad]

Dear all,
I'm simulation a 3D parabolic trough solar concentrator on ANSYS Fluent bur I have a problem defining the parabolic trough itself as a reflective surface so the solar radiation that it's receiving it has to be reflected back and concentrated on the water tube. So how can I do so?
Thanks in advance,

[vinerm]

This appears to be an Optics problem and not Fluid flow scenario. Are you sure Fluent is the tool you wish to use? You can do it using Radiation Model but if the objective is only to study optics, then better use some other tool because Fluent will be very slow for this purpose.

[andrew.saad]

Thanks for your reply.
I didn't mean in optics manner but I want to make sure that the parabolic trough reflects the radiation to concentrate it on the water pipe and I did use the radiation model already but I'm only asking if there is anything that I can do to make sure that the parabolic trough reflects the radiation as the radiation reaches it.
Thanks again for your time

[vinerm]

Then you have to consider angular dependence in radiation modeling, i.e., specular surfaces and not diffuse. By default, all walls behave as diffuse walls.