Turbophoresis of inertial particles in inhomogeneous turbulence produced by oscillating grids

TL;DR

This study experimentally investigates turbophoresis of inertial particles in inhomogeneous turbulence generated by oscillating grids, confirming preferential accumulation in low-turbulence regions.

Contribution

It provides experimental validation of turbophoretic transport mechanisms in oscillating grid turbulence systems, isolating effects from mean flow.

Findings

Inertial particles accumulate in regions of lower turbulence intensity.

Measured particle distributions match theoretical predictions of turbophoresis.

Normalization with tracer particles isolates turbophoretic effects.

Abstract

Turbophoresis in inhomogeneous turbulent flows leads to the formation of large-scale nonuniform particle number density distributions of inertial particles. This effect is associated with an effective drift velocity directed toward regions of lower turbulence intensity and proportional to the particle Stokes time and the spatial gradient of the turbulence intensity. In the present study, turbophoretic transport is experimentally investigated in air flows generated by one-grid and two-grid oscillating turbulence systems. The flow velocity field and particle spatial distribution are measured using Particle Image Velocimetry. To isolate the effect of particle accumulation due to turbophoresis from that associated with mean fluid flow, the measured particle number density of inertial particles is normalized by the corresponding distribution obtained for noninertial tracer particles under identical flow conditions. The measurements show preferential accumulation of inertial particles in regions of lower turbulence intensity, consistent with the expected behavior of turbophoretic transport.