The effect of Reynolds number on inertial particle dynamics in isotropic turbulence. Part I: Simulations without gravitational effects

Abstract

In this study, we analyze the statistics of both individual inertial particles and inertial particle pairs in direct numerical simulations of homogeneous isotropic turbulence in the absence of gravity. The effect of the Taylor microscale Reynolds number $R_{\lambda }$ on the particle statistics is examined over the largest range to date (from $R_{\lambda }=88-597$). We first explore the effect of preferential sampling on the single-particle statistics, and use our understanding of preferential sampling to provide a physical explanation for many of the trends in the particle velocity gradients, kinetic energies, and accelerations at low $St$. As $St$ increases, inertial filtering effects become more important, causing the particle kinetic energies and accelerations to decrease. We then consider particle-pair statistics, and focus our attention on the relative velocities and radial distribution functions (RDFs) of the particles. The relative velocity statistics indicate that preferential-sampling effects are important for $St\lesssim 0.1$ and that path-history/non-local effects become increasingly important for $St\gtrsim 0.2$. The lower-order relative velocity statistics are only weakly sensitive to changes in Reynolds number at low $St$. We find that the RDFs peak near $St$ of order unity, that they exhibit power-law scaling for low and intermediate $St$, and that they are largely independent of Reynolds number for low and intermediate $St$. We also observe that at large $St$, changes in the RDF are related to changes the scaling exponents of the relative velocity variances. The particle collision kernel is found to be largely insensitive to the flow Reynolds number, suggesting that relatively low-Reynolds-number simulations may be able to capture much of the relevant physics of droplet collisions and growth in the adiabatic cores of atmospheric clouds.

37 pages, 23 figures

References in corpus (6)

• Heavy particle concentration in turbulence at dissipative and inertial scales
• P3DFFT: a framework for parallel computations of Fourier transforms in three dimensions
• Caustic activation of rain showers
• Sling effect in collisions of water droplets in turbulent clouds
• The effect of Reynolds number on inertial particle dynamics in isotropic turbulence. Part II: Simulations with gravitational effects
• Lyapunov exponents of heavy particles in turbulence

Cited by in corpus (42)

• Experimental study of inertial particles clustering and settling in homogeneous turbulence
• The effect of Reynolds number on inertial particle dynamics in isotropic turbulence. Part II: Simulations with gravitational effects
• Is vortex stretching the main cause of the turbulent energy cascade?
• Multiscale preferential sweeping of particles settling in turbulence
• Statistical models for the dynamics of heavy particles in turbulence
• Cascade Model for Planetesimal Formation by Turbulent Clustering
• Dynamics of small heavy particles in homogeneous turbulence: a Lagrangian experimental study
• Effects of Reynolds Number and Stokes Number on Particle-pair Relative Velocity in Isotropic Turbulence: A Systematic Experimental Study
• Settling and Clustering of Snow Particles in Atmospheric Turbulence
• An experimental study on the multiscale properties of turbulence in bubble-laden flows
• Small-scale dynamics of settling, bidisperse particles in turbulence
• Multiscale fluid--particle thermal interaction in isotropic turbulence
• Orientation Dynamics of Sedimenting Anisotropic Particles in Turbulence
• Effect of turbulence on collisional growth of cloud droplets
• Role of pulsatility on particle dispersion in expiratory flows
• Local analysis of the clustering, velocities and accelerations of particles settling in turbulence
• Hydrodynamic interactions and extreme particle clustering in turbulence
• Scale-dependent statistics of inertial particle distribution in high Reynolds number turbulence
• Flow structures govern particle collisions in turbulence
• Divergence and convergence of inertial particles in high Reynolds number turbulence
• Particle Radial Distribution Function and Relative Velocity Measurement in Turbulence at Small Particle-Pair Separations
• Exploring the turbulent velocity gradients at different scales from the perspective of the strain-rate eigenframe
• Breakthrough revisited: investigating the requirements for growth of dust beyond the bouncing barrier
• Gauge symmetry and dimensionality reduction of the anisotropic pressure Hessian
• The influence of Reynolds and Froude number on the motion of settling, bidisperse inertial particles in turbulence
• Bubble-particle collisions in turbulence: insights from point-particle simulations
• Dust Coagulation Regulated by Turbulent Clustering in Protoplanetary Disks
• Spectral characterisation of inertial particle clustering in turbulence
• Scale Dependence of Multiplier Distributions for Particle Concentration, Enstrophy and Dissipation in the Inertial Range of Homogeneous Turbulence
• Heavy Particle Clustering in Inertial Subrange of High--Reynolds Number Turbulence
• Quantitative prediction of sling events in turbulence at high Reynolds numbers
• Analysis of the forward and backward in time pair-separation PDFs for inertial particles in isotropic turbulence
• Irreversibility-inversions in 2 dimensional turbulence
• Do fluid particles separate exponentially in the dissipation range?
• Lagrangian tracking of colliding droplets
• Characterizing 1D Inertial Particle Clustering
• The effect of gravity on bubble-particle collisions in turbulence
• Developments and difficulties in predicting the relative velocities of inertial particles at the small-scales of turbulence
• Pair statistics of oblate spheroids settling in a turbulent flow
• Fluid dynamics in clouds: The sum of its parts
• Spectral response between particle and fluid kinetic energy in decaying homogeneous isotropic turbulence
• Polydisperse collision kernels in droplet-laden turbulence with implications for rain formation