[ahmed98]

Hi All,
I am simulating a solar receiver which consists of water passing by upper and lower glass layers to capture heat.
I want the fluent to solve and find the transmitted radiation from the lower glass but unfortunately, I have to put values for the irradiation!

My model is DO radiation + laminar incompressible flow. As we know, for 1 cm of water, water will absorb almost 26% of the solar radiation. Unfortunately, the simulation results show that the energy transmitted from the lower glass layer is very low and the water almost captured all the radiation.

My BC are as follows:
Upper glass: Thermal: mixed heat transfer, h = 9.5w/m2k, free stream T = 300k, External emissivity = 0.8, external radiation T = 287k, Radiation: BC type = semi transparent, Direct irradiation = 110000w/m2 (concentrated sunlight), Diffuse irradiation = 0, Diffuse fraction = 0

Lower glass: Same thermal BC, Radiation: I dont know what to do. Should I put the Direct irradiation and Diffuse irradiation = 0? I did that and I got these weird results.

What should I do?

Thank you all.