Unsteady Mixed Convection Over Spinning Isothermal Bodies With Blowing and Suction

Initial development of the laminar thermal boundary-layer flow over an impulsively started translating and spinning axisymmetrical isothermal body with blowing and suction in the case of mixed convection is investigated. Velocity components and temperature are expanded in series in powers of the square root of time. Leading, first and second order functions are obtained analytically and the third, forth and fifth order functions are determined numerically. Application of the general results to a sphere shows that buoyancy driven aiding and opposing flows help surface suction in retarding and surface blowing in facilitating the onset of flow separation respectively. Surface heat flux is increased near the front stagnation point due to the axial inflow created by the body spin and enhanced by the circulating flow inside the separated region. Surface suction is found to increase the heat transfer while the surface blowing decreases it. Aiding and opposing flows increase the surface heat flux around the front and rear stagnation points respectively.