Flow and Heat Transfer from a Rotating Sphere Partially Immersed in a Bounded Stationary Fluid

For the first time, a numerical study has been carried out to investigate the flow and heat transfer from a partially immersed rotating sphere in a bounded boundary stationary fluid with variable distances from its surface. The simulations are performed for different boundary distances under various types of rotational speed of the sphere using the two-phase VOF model. The flow and thermal fields are investigated through streamlines, isotherm, and volume fraction contours, as well as through the average Nusselt number and the thickness of the water film. The numerical results demonstrate that the water is drawn up the sphere's lower pole because of the centrifugal force generated by the rotation, and its motion continues due to the water film formation. Then, the water film is radially thrown out because of the inertial forces dominance. Moreover, the sinusoidal pulsation rotational speed indicates higher heat transfer performance among various functions. Compared with the exponential function by increasing the boundary radius from R-infinity = 7 cm to R-infinity = 10 cm the time -surface -averaged Nusselt number increases by about 35%. Also, it is found that as the immersion angle increases from theta(i )= 30(degrees) to theta(i) = 60(degrees), surface-averagedusselt number increases by about 51% on average for the uniform rotational speed of the sphere.