Computational analysis of thermal enhancement and flow dynamics in lid-driven staggered cavities with uniform/nonuniform temperature walls

This research explores mixed convection resulting from simultaneous natural
and forced heat exchange in a lid-driven staggered cavity occupied by a
Newtonian fluid. All boundaries maintain no-slip conditions, except the top
wall, which moves with the 𝑈𝐿𝑖𝑑 velocity. Assumptions are made, including
two cases of uniform and nonuniform heated left wall and the maintenance
of cold walls throughout the cavity, which disrupts thermal equilibrium.
CFD simulations are carried out by employing finite element (FEM) routine
available in COMSOL Multiphysics software to elucidate the dimensionless
problem and obtain the optimal results with desired accuracy. In this study
we incorporated detailed examination of flow parameters, such as Reynolds
number (1 ≤ 𝑅𝑒 ≤ 100), Grashof number (103 ≤ 𝐺𝑟 ≤ 106), Prandtl number
(0.015 ≤ 𝑃𝑟 ≤ 10) and Richardson number (0.1 ≤ 𝑅𝑖 ≤ 10) on dominant flow
motions in the designed staggered cavity. Local heat flux and kinetic energy for
uniform and non-uniform cases provide insights into heat distribution. Increased
Reynolds numbers decrease fluid kinetic energy, while higher Grashof values
enhance thermal buoyancy forces, raising the Nusselt number. For uniform heat
source the average Nusselt number (𝑁𝑢𝑎𝑣𝑔) rises significantly by the Grashof
number (𝐺𝑟), especially for higher Prandtl numbers (𝑃𝑟 = 10), indicating strong
convective heat transfer. Lower Prandtl numbers (𝑃𝑟 = 0.015) exhibit minimal
increases, showingweaker convection.While for non-uniform heat source While
Nuavg also rises with 𝐺𝑟, the overall values and slopes are lower compared to the
uniform heat source case. High Prandtl numbers still enhance heat transfer, but
the effect is less pronounced, and low 𝑃𝑟 fluids show minimal sensitivity to 𝐺𝑟.
Higher Reynolds numbers also accelerate the clockwise rotational structure, as
indicated by the streamlines.