Alignment response time for non-spherical particles in turbulence

Abstract

Evolution of spheroidal particle orientation in turbulence is a fundamental problem in particle-laden flows. In this study, we introduce a response time for the spheroidal particle orientation in turbulence, representing a time scale for the particle with different initial orientations aligned to a certain direction along a Lagrangian trajectory. This time scale characterises how fast the spheroids align in turbulence, and is analysed by direct numerical simulations of inertialess spheroids in homogeneous isotropic turbulence with Taylor Reynolds numbers ranging from 30 to 418. Our results reveal a power-law relationship between this response time scaled by Kolmogorov time scale and the shape parameter of spheroids.