Magnetohydrodynamic flows in a dis-aligned duct system under a uniform magnetic field

Abstract

In the present study, three-dimensional Magnetohydrodynamic (MHD) Liquid-metal (LM) flows in a dis-aligned duct system under a uniform magnetic field are investigated by numerical method. Computational fluid dynamics (CFD) simulations are carried out to analyzed the characteristics of the MHD flows and to examine the inter-relationship of the LM velocity, current density, electric potential and pressure, using CFX. The duct system consists of two dis-aligned parallel channels (One inflow channel and one outflow channel) and one channel connecting the above channels. In the present study, cases with different lengths of the connecting channel are considered. Because of the inertial force therein, a velocity recirculation is found in the region just after the first turning, resulting in a region of peak value in electric potential together with complex distribution of the current. Also, another velocity recirculation is seen in the region just after the second turning, creating another region of peak value in electric potential. In a situation where the magnetic field is applied in a direction perpendicular to the plane of the main flow in a dis-aligned duct system, until the fluid reaches an edge, the velocity component parallel to the magnetic field converges, with an increasing in the peak value of the side layer velocity, and then, after the fluid passes the edge, the velocity component parallel to the magnetic field diverges, with a decrease in the peak value of the side layer velocity. Oppositely, until the fluid reaches a corner, the velocity component parallel to the magnetic field diverges, with a decrease in the peak value of the side layer velocity, and then, after the fluid passes the corner, the velocity component parallel to the magnetic field converges, with an increase in the peak value of the side layer velocity. It is found that this type of velocity pattern is closely associated with the current distribution in the region of right-angle segments in the sense that the magnitude of the electromotive component of electric current is proportional to the fluid velocity.