Comparing velocity and passive scalar statistics in fluid turbulence at high Schmidt numbers and Reynolds numbers

Abstract

Recently, Shete et al. [Phys. Rev. Fluids 7, 024601 (2022)] explored the characteristics of passive scalars in the presence of a uniform mean gradient, mixed by stationary isotropic turbulence. They concluded that at high Reynolds and Schmidt numbers, the presence of both inertial-convective and viscous-convective ranges, renders the statistics of the scalar and velocity fluctuations to behave similarly. However, their data included Schmidt numbers of 0.1, 0.7, 1.0 and 7.0, only the last of which can (at best) be regarded as moderately high. Additionally, they do not consider already available data in the literature at substantially higher Schmidt number of up to 512. By including these data, we demonstrate here that the differences between velocity and scalar statistics show no vanishing trends with increasing Reynolds and Schmidt numbers, and essential differences remain in tact at all Reynolds and Schmidt numbers.

arXiv commentaccepted and to be published in Physical Review Fluids as a Comment

References in corpus (8)

• Extreme velocity gradients in turbulent flows
• Very fine structures in scalar mixing
• Vortex stretching and enstrophy production in high Reynolds number turbulence
• Small-scale isotropy and ramp-cliff structures in scalar turbulence
• Turbulence is an ineffective mixer when Schmidt numbers are large
• Vorticity-strain rate dynamics and the smallest scales of turbulence
• Generation of intense dissipation in high Reynolds number turbulence
• Intermittency of turbulent velocity and scalar fields using 3D local averaging