[alainislas]

Hello,

I am simulating the cooling of a hot block (uniform T = 1000 K) surrounded by water at 20°C. The water fills a perfect box and remains quiescient, while the solid block just rests at the bottom. I am in natural convection regime. However, since I want to capture the transient evolution of the BL, I refined the fluid cells proximate to the solid wall.

iso-view.PNG
fluid_fine_layer.PNG

For the fluid/solid interface I am using

type compressible::turbulentTemperatureCoupledBaffleMixed;
Tnbr T;
value $internalField;

When I run the case with the fine mesh I get weird results, there is a cold spot at one of the walls of the block. After only 1 sec, the simulation diverges and throws the error: FOAM FATAL ERROR: Negative Initial Temperature T0: -3.1820139

fine_layer.PNG


However, when I run the case with mesh with no-wall refinement, the simulation runs easily up to 50s and the results seem more reasonable.

no_layer.PNG

Does anyone know how to address this issue without sacrifying the near-wall cells?