Cfx: local skin friction coefficient Cp: specific heat at constant pressure f: dimensionless stream function g: gravitational acceleration (ms−2) Tc: low temperature at the upper wall (K) Th: high temperature at the bottom wall (K) T¥: temperature of the ambient fluid (K) Gr: Grashop number Ha: Hartmann number | Pr: Prandtl number, υ/α q: Heat flux (Wm?2) Ra: Rayleigh number T: temperature of the fluid in the cavity (K) Nu: Nusselt number U V: Dimensionless velocity components along X, Y-direc- tion |