Anisotropic resistance effects on particle dispersion in turbulence

Particle-laden turbulent flows are important in both natural and industrial contexts. The particles in many of these processes, such as the formation of ice crystals in clouds or the paper-making process, are anisotropic, with directionally-dependent drag coefficients. Generally, anisotropic particles are free to rotate as they are advected by the carrier fluid. However, external forcing from gravitational and magnetic fields, the larger scale flow, and active behavior can restrict the particles’ orientation, fixing their anisotropic resistance with respect to the reference frame. The dynamics and statistics of symmetric particles in isotropic turbulence are well-studied, but the effect of anisotropic forcing on the transport and behavior of asymmetric particles is less well-understood. We studied these dynamics by conducting Lagrangian particle tracking in simulated isotropic turbulence from the Johns Hopkins Turbulence Database. Anisotropy was introduced by either directly scaling tracer-particle velocity or applying directionally-dependent Stokes drag and density parameters to particles simulated with the Maxey-Riley equations. We examine how increasing a particle’s resistance to motion in one direction in isotropic turbulence impacts the transport and dispersion statistics in all three directions.