melting of pcm in cylindrical annnulus?
 

Hi all;

i want to modelling melting of pcm in cylindrical annnulus. Phase change material(pcm) is located in concentric annulus and fluid is passed thorough at inner tube. i want to model melting of pcm. i draw the geometry in GAMBIT as 2D. in FLUENT, i select solidifacation/melting model. i defined material.

at the surface of the inner tube, i could not define third type (convection) boundary condition. (thermal resistance of the wall is negligible). Even i select first type boundary condition, pcm does not melt logically. how can i solve this problem?

tkanks.

sorry for my bed english.