Influence of insulating and conducting walls on magnetohydodynamic flow in a suddenly expanded channel: A numerical study

In this study, we conducted numerical simulations using the robust code AnuPravaha. The code’s performance was rigorously validated by benchmarking it against a range of standard cases, including Shercliff and Hunt’s cases. The same AnuPravaha code is used to identify the effect of conduction and insulating walls on a suddenly expanded channel for low Hartmann number ranging from 10–100 and Reynolds number ranging from 100–500. The results finding indicate that at a low Hartmann number Ha ≤ 40, the effect on the flow profile remains negligible. As the Hartmann number increases Ha > 40, it generates a more crescent-shaped profile, reducing the centerline flow velocity and increasing it near the side walls. It is also observed that variations in pressure drop are minimal within the low Hartmann number range of Ha = 10–30 but become very significant for a higher Hartmann number (Ha > 30). For a change in Hartmann number from Ha = 20 to Ha = 40, the pressure drop rises by 212% and at Hartmann number from Ha = 50 to Ha = 100, it increases by 284% indicating an amplification effect on the magnetic field at a higher Hartmann number. The pressure drop achieved in Insulating walls is far lesser than the conduction walls as insulating walls don’t allow any current-wall interaction. It is found that by using insulating walls the average pressure drop is reduced by about 94%. At a fixed Reynolds number, insulating walls yield higher outlet velocities than conduction walls due to lower Lorentz force resistance which modifies the volumetric heating effects. Increasing Hartmann number reduces the velocity difference between both types of walls.