Inertial chiral particles affect homogeneous turbulence vorticity

We present results from direct numerical simulations of chiral finite-size inertial particles, under the effect of gravity in a tri-periodic domain with homogenous isotropic turbulence. Although the interest in turbulent inertial particle-laden flows has increased in the last decade, most of the previous studies have mainly focused on highly symmetrical particles (i.e. spheres or ellipsoids) either with or without inertia. In this study we introduce chiral and convex particles whose size is in the turbulence inertial range.

Chirality is a property of anisotropy for which an object is distinguishable from its mirror image. Thanks to this feature, our particles brake spatial reflexion symmetry, coupling translational and rotational degrees of freedom. Moreover, in all our simulations, the carrier and the dispersed phases are two-way coupled and collisions among particles are also taken into account.

We observe a turbulence modulation that increases with the increase of particles volume fraction and the same energy spectra scaling of turbulent bubbly flow. Chiral particles, falling under gravity, show a preferential angular velocity both in quiescent and turbulent flows. The most important evidence of this behaviour is observed in the vorticity statistics, highlighting a Froude number effect. Indeed, we observe a skewed distribution of the vertical vorticity component with a positive or negative peak depending on the particular chirality chosen.