Unsteady heat and mass transfer from a rotating vertical cone with a magnetic field and heat generation or absorption effects

This work is focused on the study of unsteady heat and mass transfer by mixed convection flow over a vertical permeable cone rotating in an ambient fluid with a time-dependent angular velocity in the presence of a magnetic field and heat generation or absorption effects. The cone surface is maintained at variable temperature and concentration. Fluid suction or injection is assumed to occur at the cone surface. The coupled nonlinear partial differential equations governing the thermosolutal mixed convective flow have been solved numerically using an implicit, iterative finite-difference scheme. Comparisons with previously published work have been conducted and the results are found to be in excellent agreement. A parametric study showing the effects of the buoyancy parameter, suction or injection velocity and heat generation or absorption coefficient on the local tangential and azimuthal skin friction coefficients, and the local Nusselt and Sherwood numbers is conducted. These are illustrated graphically to depict special features of the solutions. It is found that the local tangential and azimuthal skin-friction coefficients and local Nusselt and Sherwood numbers increase with the time when the angular velocity of the cone increases, but the reverse trend is observed for decreasing angular velocity. However, these are not mirror reflection of each other. Increasing the buoyancy ratio is predicted to increase the skin-friction coefficients and the Nusselt and Sherwood numbers. Also, increases in the heat generation or absorption coefficient increase the local tangential skin-friction coefficient and Sherwood number and decrease the local Nusselt number. On the other hand, the azimuthal skin-friction coefficient and the Nusselt and Sherwood numbers increase (decrease) with the increase in the suction (injection) parameter. (c) 2004 Elsevier SAS. All rights reserved.