The return to isotropy in anisotropic turbulence is a fundamental topic in turbulence research, providing critical insights into the structural evolution of turbulent flows. While turbulence originates in marked directional dependencies—driven by boundary constraints or external
forcing—the decay toward an isotropic state remains a fundamental transition for accurate modeling. This evolution is particularly critical in configurations where thermal gradients are present. The present study uses Large Eddy Simulation (LES) to analyze the return to isotropy of anisotropic flows in the presence of a thermal field. We prioritize the intricate coupling between velocity and temperature fluctuations, a nexus governing many industrial and environmental transport phenomena. By dissecting the individual terms in the Reynolds-stress and heat-flux budget equations, this work quantifies the temporal dynamics of the pressure-scalar correlation, identifying it as a pivotal closure challenge for advanced heat-flux parameterization. Comparisons with direct numerical simulation data reported by Iida and Kasagi show good agreement, particularly when anisotropy weakens at times greater than 2. These findings contribute to improved optimization of model constants, enhancing the accuracy of turbulence modeling.