CHT with combustion error
​
I am modeling premixed propane combustion in an atmospheric burner with conjugate heat transfer (CHT). The object is not a baking oven. It’s the MICCA laboratory combustion chamber from EM2C. It has a very low maximum mass-flow-averaged velocity of 0.6 m/s.
I use the SST turbulence model and the eddy dissipation model for combustion, together with the Westbrook and Dryer 2-step mechanism. I started modeling with only a tetrahedral mesh and without solid domains, because I got errors involving extremely low temperature in the boundary prismatic layers. After the first solution was interpolated onto the fluid mesh with prismatic boundary layers, I also got a normal solution. Unfortunately, when I tried to interpolate the last solution onto the CHT case, I got the same error after 70 iterations. The solid domain was initialized with a temperature of 300 K.
The time step for the fluid is 0.0002 s, and for the solid it is 0.01 s. After the first time steps, the temperature in the boundary layers decreased to 200 K.
For the solid-fluid interfaces, I use a conservative interface flux with zero thermal contact resistance.
Where am I making a mistake?