Hello everyone, I have this setady state, heat transfer problem; I hope you can help me with it. I have flux source of 400 W/m² (a lamp), and i want to calculate the heat flux passing through a surface arbitrarily placed and oriented in the space. There is air in between. How can i do this? I thought that I could use ∫∫(-k∇T)*(n dS) But i dont know what ∇T is.... Thanks.