Size effect of forces on natural convection in a square cavity

Microscale natural convection plays an important role in numerous engineering applications such as micro electro-mechanical systems (MEMS) and the cooling of electronic equipment. Numerical calculations were used to clarify the differences between microscale and macroscale natural convection. The studies analyzed the relative importance of the inertial force to the viscous force and the flow and heat transfer in natural convection in a square cavity with Ra ranging from 1 to 10⁸. The results reveal that relative to the inertial force, the viscous force becomes more and more important as the scale decreases with the viscous force dominating for Ra<10³, which accounts for the differences between microscale and macroscale natural convection.