Magneto‐thermogravitational convective flow of hybrid nanomaterial within an enclosure subject to partially active side walls

Abstract Natural convection, driven by buoyancy, is utilized for the heat transport in various applications including thermal exchangers, cooling of heat sources, solar collectors, geothermal power systems, electronic devices, microelectronics, and nuclear industries. This research focuses on the free convection of a hybrid nanoliquid containing Ag–MgO nanoparticles in an enclosure having partially active borders. The hybrid nanosuspension utilized is a mixture of MgO and Ag nanoparticles in equal proportions, suspended in water as the base liquid. The square enclosure is subject to the Lorentz force impact. The study examines two cases. In Case 1, the left wall experiences heat dissipation via a heat sink at a fixed temperature T c , whilst the right wall is partly affected by the active chamber borders with a heater at temperature T h (where T h > T c ). The rest sections of vertical borders are adiabatic. In addition, the cavity is thermally insulated on both the upper and lower surfaces. In Case 2, the chamber's vertical sides are heated to a certain extent ( T h ), whereas the bottom wall is somewhat cold ( T c ) and has some level of activity. The remaining inactive sections of the cavity are adiabatic. The control flow equations were resolved with the help of COMSOL Multiphysics, which is complex modelling software for computational fluid dynamics (CFD). The computational study has been performed with the following parameters, Rayleigh number ( Ra ) = 10 3 –10 6 , Hartmann number ( Ha ) = 0–80, and nanoparticles volume fraction (ϕ) = 0.01, 0.02. The effect of important variables, such as Hartmann and Rayleigh numbers, in conjunction with the concentration of nano additives has been examined by analyzing streamlines and isotherms to understand their effect on thermal convection. It is found from the isotherms within the cavity in Case 2, that increment in Ha leads to slight rise the temperature within the cavity. Further, in Case 1, Nu avg is decreasing function of Ha and Q . While in Case 2, the average Nu is decreasing function of Q and increasing function of Ra and ϕ.