Aiding and opposing mixed convection flows over the Riga-plate

The Blasius flow of an electrically conducting fluid over the Riga-plate is considered. The Riga-plate is an electromagnetic actuator which consists of a spanwise aligned array of alternating electrodes and permanent magnets mounted on a plane surface. This array generates a surface-parallel Lorentz force which decreases exponentially in the direction normal to the plate. The governing parameter of the title problem is the modified Hartmann number Z, which is positive when the Lorentz points in the direction of the free stream (aiding flow) and negative when it is opposite to the free stream (opposing flow). The characteristics of physical and engineering interest of these doubly driven aiding and opposing mixed convection flows are discussed in the paper in detail.