Attenuation of turbulence in a periodic cube by finite-size spherical solid particles

TL;DR

This study uses direct numerical simulations to explore how finite-size spherical particles attenuate turbulence in a periodic cube, revealing key factors like particle size and wake energy dissipation that influence turbulence reduction.

Contribution

It introduces a formula linking particle size and turbulence attenuation, providing new insights into turbulence control via solid particles in fluid flows.

Findings

Particles with size proportional to λ/√γ most effectively reduce turbulence.

Energy dissipation in particle wakes correlates with turbulence attenuation.

Proposed formulae predict conditions for turbulence suppression.

Abstract

To investigate the attenuation of turbulence in a periodic cube due to the addition of spherical solid particles, we conduct direct numerical simulations using an immersed boundary method with resolving flow around each particle. Numerical results with systematically changing particle diameters and Stokes numbers for a fixed volume fraction $\Lambda$ show that the additional energy dissipation rate in the wake of particles determines the degree of the attenuation of turbulent kinetic energy. On the basis of this observation, we propose the formulae describing the condition and degree of the attenuation of turbulence intensity. We conclude that particles with the size proportional to $\lambda/\sqrt{\gamma}$, where $\lambda$ and $\gamma$ are the Taylor length and the mass density ratio between particles and fluid, most significantly reduce the intensity of developed turbulence under the condition that $\gamma$ and $\Lambda$ are fixed.