Viscous dissipation effects on mixed convection about a rotating sphere

The effect of viscous dissipation on mixed convection flow about a rotating sphere is investigated analytically. A method based on Merk's type of series expansions is used to obtain the heat transfer rate and the skin-friction coefficients. Numerical computations were carried out for Eckert number Ec ranging from 0 to 0.1, rotation parameter B = 0, 1, 4 and buoyancy parameter ranging from 0 to 1 at various angular positions. As viscous dissipation increases heat transfer rate decreases. It is found that for Ec > 0, a critical value of B (say B cri) exist such that Nu Re R − 1 2 increases as B increases up to B = B cri and then decreases. B cri decreases with Ec when the angle is fixed or decreases with angle when Ec is fixed. When Ec > 0, possibly there exist a λ, say λ cri, such that Nu Re R − 1 2 increases with λ up to λ = λ cri and then decreases. Also the effect of viscous dissipation on skin friction is investigated.