The present study numerically investigates the influence of sinusoidal thermal boundary conditions imposed on the sidewalls of a square chamber on natural convective flow and heat transfer of a micropolar fluid. The vertical sidewalls are subjected to non-uniform thermal conditions characterized by a sinusoidal temperature profile consisting of alternating heating and cooling zones, defined by amplitude and phase deviation. The horizontal walls are maintained under adiabatic conditions. The governing nonlinear system of partial differential equations is solved using the finite volume method. Numerical simulations are performed for various combinations of the relevant governing parameters. The results reveal that the local Nusselt number varies sinusoidally along the heated wall, while the average Nusselt number increases with higher amplitude ratios. Furthermore, phase deviation substantially enhances heat transfer along the right sidewall, as reflected by higher local Nusselt number variations, whereas its influence on the left sidewall remains comparatively weak.
