Spatial Distribution of Inertial Particles in Turbulent Taylor-Couette Flow

TL;DR

This paper uses direct numerical simulations to analyze how inertial particles distribute in turbulent Taylor-Couette flow, revealing dominant effects like centrifugal force, turbophoresis, and biased sampling on particle clustering and migration.

Contribution

It introduces a detailed analysis of particle distribution mechanisms in turbulent Taylor-Couette flow, highlighting the roles of centrifugal effects, turbophoresis, and biased sampling, with implications for industrial control.

Findings

Centrifugal force causes particles to migrate outward.

Turbophoresis influences larger particles towards walls.

Biased sampling affects smaller particles near Taylor rolls.

Abstract

This study investigates the spatial distribution of inertial particles in turbulent Taylor-Couette flow. Direct numerical simulations are performed using a one-way coupled Eulerian-Lagrangian approach, with a fixed inner wall Reynolds number of 2500 for the carrier flow, while the particle Stokes number varies from 0.034 to 1 for the dispersed phase. We first examine the issue of preferential concentration of particles near the outer wall region. Employing two-dimensional (2D) Voronoi analysis, we observe a pronounced particle clustering with increasing $St$, particularly evident in regions of low fluid velocity. Additionally, we investigate the concentration balance equation, inspired by the work of johnson et al.(2020), to examine particle radial distribution. We discern the predominant sources of influence, namely biased sampling, turbophoresis, and centrifugal effects. Across all cases, centrifugal force emerges as the primary driver, causing particle migration towards the outer wall. Biased sampling predominantly affects smaller inertial particles, driving them towards the inner wall due to sampling within Taylor rolls with inward radial velocity. Conversely, turbophoresis primarily impacts larger inertial particles, inducing migration towards both walls where turbulent intensity is weaker compared to the bulk. With the revealed physics, our work provides a basis for predicting and controlling particle movement and distribution in industrial applications.