Effect of near-wall blockage on the magnetohydrodynamics-based double-diffusive convection in rectangular cavities

This research work reports the numerical investigation of magnetohydrodynamics (MHD) characteristics around the near-wall blockage (Formula presented.) for various separation distances owing to double-diffusive convection (DDC) in a rectangular cavity. The distance between the bottom wall of the cavity and the lower wall of blockage is called separation distance (Formula presented.) and it has varied from (Formula presented.) where H is the height of the cavity. The working fluid is considered as liquid metal - Sodium-Potassium alloy ((Formula presented.)). The numerical computations are conducted by using an in-house developed lattice Boltzmann method (Formula presented.) solver. The simulations are conducted for the steady-state, laminar, incompressible, and Newtonian fluid flow. The effect of NWB has been explored for a range of parameters, such as Rayleigh number (Formula presented.) and (Formula presented.) Lewis number (Formula presented.) buoyancy ratio (Formula presented.) and Hartmann number (Formula presented.) The variation and contour plots show the higher heat and mass transfer (HMT) rates for (Formula presented.) at constant Ra. As (Formula presented.) increases, HMT rates enhance. The increase in Ra, N, and Le induces multiple-cell formation inside the cavity for a given (Formula presented.) As Ha augments HMT rates get decreased monotonically. For (Formula presented.) negligible or slight variation was observed in the rate of HMT. As the obstruction between the bottom wall of the blockage and the adiabatic bottom wall of the cavity increases, shear force occurs, and the buoyancy-driven flow decreases. The outcomes of the numerical investigation are summarized in the form of empirical correlation of (Formula presented.) for Ra = (Formula presented.) and (Formula presented.) at various separation distances, which might be utilized for probable design purposes.