Good Morning,

So here are my thoughts based on those images:

  • First look under Reports -> Fluxes -> Total heat transfer rate and then select the surfaces. Compare these between the cases.
  • For each of the walls you have section2 and section2.shadow correct? When you have it set up for coupled, then any changes that occur on one side of the wall will automatically be applied to the other side. This means these two sides are coupled together. On the other hand, when you have the heat flux, then you can set different values for either side. This means that for cases 1 & 2 you effectively have double the loading of the case 3. I hope the results from the flux report demonstrate this.

As for the comparison of the model to the experiment

  • You are running these as transient, correct? What are you using to judge convergence per timestep? It is very likely that the energy RMS values will be converged below 1e-6 before the temperature on each heater is converged. Set-up a monitor point on each of these heated sections and see if it is converged before moving on to the next time step. It could be the error associated with this is causing the under-prediction.
  • In my last post I asked if the sections planes or pipes in the experiment. How we compare the results with the experiment will be a little different between the two. If it is the former the results should match up pretty well. If it is the latter, we can discuss further.