This study investigates the turbulent characteristics of supercritical fluids using open source DNS database, focusing on thermal property variations, Reynolds stress dynamics, and flow behavior at transcritical conditions. Results reveal that pressure remains nearly constant across the channel, with temperature-driven compressibility dominating flow adjustments. Near the hot wall, density fluctuations exceed 40%, invalidating the Morkovin hypothesis, while specific heat capacity fluctuations surpass 90%, highlighting the necessity to account for thermal property variability. Reynolds stress distributions exhibit similar peak trends across conditions but resist normalization due to strong density fluctuation impacts. Analysis of the Reynolds stress transport equation shows viscous sublayer dynamics governed by dissipation and diffusion terms, whereas production and pressure-strain terms dominate the logarithmic layer, crucially regulating turbulent kinetic energy redistribution. Instantaneous snapshots link temperature-induced density fluctuations to streamwise velocity variations, driving Reynolds stress generation near walls. These findings challenge traditional turbulence models and provide critical insights into transcritical heat transfer mechanisms, offering a foundation for optimizing supercritical fluid applications in engineering systems. Further instantaneous analysis discloses that temperature fluctuations induce density fluctuations, which in turn trigger streamwise velocity fluctuations; these streamwise fluctuations couple with wall-normal velocity fluctuations to generate Reynolds stress.
Based on the above analysis, this paper proposes an improved framework for the Reynolds stress transport model, providing a theoretical foundation for turbulence modeling of transcritical flows with high density ratios.