Phoresis in turbulent flows

TL;DR

This paper investigates how phoretic effects, caused by scalar gradients, influence particle dispersion in turbulent flows, combining theoretical predictions with numerical simulations to understand their potential impact in natural systems.

Contribution

It introduces a dimensionless number to quantify phoretic effects on particle dispersion and validates simple predictive models with direct numerical simulations.

Findings

Phoretic effects can significantly alter particle separation in turbulence.

A single dimensionless number effectively characterizes the phoretic influence.

Results suggest potential implications for natural systems involving scalar-driven particle transport.

Abstract

Phoresis, the drift of particles induced by scalar gradients in a flow, can result in an effective compressibility, bringing together or repelling particles from each other. Here, we ask whether this effect can affect the transport of particles in a turbulent flow. To this end, we study how the dispersion of a cloud of phoretic particles is modified when injected in the flow, together with a blob of scalar, whose effect is to transiently bring particles together, or push them away from the center of the blob. The resulting phoretic effect can be quantified by a single dimensionless number. Phenomenological considerations lead to simple predictions for the mean separation between particles, which are consistent with results of direct numerical simulations. Using the numerical results presented here, as well as those from previous studies, we discuss quantitatively the experimental consequences of this work and the possible impact of such phoretic mechanisms in natural systems.