Ash/Air multiphase heat exchanger
 

I'm simulating an heat exchange between air and ash inside a multiphase cooler. I did a preliminar analysis supposing a restitution coefficient for walls equal to 1, and the run reached quickly convergence.
But when I switched the restitution coefficient for walls equal to 0.05, the run didn't reach convergence.
Wich parameters could I modify or set to solve the problem? :confused:
Thanx