Can anyone please tell me the topics I need to study from Fluid Mechanics, specially fluid dynamics to understand Heat Transfer in a better way?
Fluid mechanics is mostly used in handling convection problem, whether it is forced convection or natural convection. Additionally, on those two problems the concept that is used is mostly dimensionless number (like Re, Gr, Pr, etc.) and that's it, and also boundary layer concept. If there is one concept that you should try to understand, I think try to learn what those dimensionless number tell you about how the fluid behave.