Schmidt Number and its influence on turbulent energy dissipation in aeolian sand transport phenomena

Abstract

This study examines the role of the turbulent Schmidt number (Sc) in shaping the dynamics of aeolian sand transport, with a particular focus on turbulent energy dissipation and particle diffusion. Using a mixture model framework and direct numerical simulations, we investigate both suspension (D = 2 μm) and saltation (D = 250 μm) modes under controlled wind tunnel conditions. Results demonstrate that Sc strongly influences diffusion coefficients and dissipation rates, with a stable convergence identified in the range Sc = 0.7–0.9. This interval represents a physically meaningful threshold where the turbulence structure of air–sand flows remains relatively insensitive to Sc variations. The findings provide not only a refined parameterization of aeolian transport but also a basis for improving predictive models of dust storms, atmospheric pollutant dispersion, and environmental risk assessments. This work highlights the importance of treating Sc as a tunable parameter in environmental fluid dynamics rather than as a fixed constant.