Numerical Insights of Mixed Convection in a Square Cavity with an Insulated Vertical Strip

Abstract

In this study we evaluate how an insulated vertical strip functions as a heat regulating element to govern fluid motion together with heat transfer in square cavities. In previous studies, the researchers have given a limited attention to investigating the insulated strips with the use of the multi-relaxation time lattice Boltzmann method. The vertical strip divides the cavity exactly in the middle as both walls of the enclosure operate with oppositely moving lids having the upper wall heated and the lower one cold. The remaining walls within the enclosure hold adiabatic characteristics. The behavior of flow and heat transfer within the enclosure are governed by the principles of mass, momentum, and energy conservation, stated via nonlinear partial differential equations along with relevant boundary conditions. To simulate these phenomena, the D2Q9 lattice methods of the multi-relaxation time lattice Boltzmann method are employed, considering the key dimensionless parameters which include the Grashof numbers from 10⁴ to 5 × 10⁵, the Richardson numbers varying between 0.1 and 100, and the Prandtl numbers ranging from 0.7 to 7. As the Grashof number increases, it promotes greater separation between the dominant vertical structures, pushing them toward the cavity walls and inducing secondary re-circulation regions in the central area. When the Richardson number receives becomes higher, it generates the strengthened buoyancy forces that squeeze the temperature contours while reshaping the thermal distribution pattern over the entire cavity domain. With rising the Grashof number, the average local Nusselt number displays a general trend for increase but exhibits low variation with changes in the Richardson number.