heat flux calculation

Hy

I do have a concrete question concerning the calculation of in and outfluxes for heat transport.

When I set an Value a.e. 10W/m² in the middle of the model. The heatflow will be sucked on both sides of my condition. Is my "real" heatflow to be calculated by Q= 2*q*l*B (B-depth of model (2d)). So the simulated out or influx would be 20 W/m² because of using both sides of the condition?

This is right. Using a 2nd kind or 3rd kind condition, there are two adjacent elements, therefore B in your notation is multiplied by two in the equation.