heat trasnfer in a engine

[burri]

hello

i'm doing some heat calculations in a combustion engine , and i would like to know how in abaqus i can simulate the convection in the chamber.
And how can use one film coeficient between the piston and the air in the chamber without use the sink temperature (because my boundary conditions is the air temperatures near the chamber walls). Use the gap conductance option is correct? using K like the convection coefficient ?

thanks in advance