Effect of thermal fluctuations on turbulent channel flow

Thermal fluctuations have been found to significantly influence the dissipation range of turbulence, an effect beyond the scope of the classical Navier-Stokes equations. In this study, we investigate their impact on turbulent channel flow by numerically solving the fluctuating hydrodynamic equations. Simulation results confirm theoretical predictions that the energy spectrum, dominated by thermal fluctuations, follows a k 2 power law. When thermal fluctuations reach sufficient intensity, they disrupt the dominant turbulent structures responsible for most of the kinetic energy, leading to a reduction in large-scale spectral energy. Additionally, thermal fluctuations increase wall skin friction by modifying mean velocity profiles. The injected energy amplifies Reynolds normal stresses while maintaining the magnitude of Reynolds shear stress. Furthermore, thermal fluctuations enhance the symmetry and homogeneity of velocity fluctuations while reducing their intermittency. Despite these effects, the balance between kinetic energy production and dissipation, including both turbulent and thermal contributions, remains preserved.