A numerical study of particle jetting in a dense particle bed driven by an air-blast

Abstract

In this work, the particle jetting behavior in a blast-driven dense particle bed is studied at early times. Four-way coupled Euler–Lagrange simulations are performed using a high-order discontinuous Galerkin spectral element solver coupled with a high-order Lagrangian particle solver, wherein the inter-particle collisions are resolved using a discrete element method collision model. Following the experiments of Rodriguez et al. [“Formation of particle jetting in a cylindrical shock tube,” Shock Waves 23(6), 619–634 (2013)] and the simulations of Osnes et al. [“Numerical simulation of particle jet formation induced by shock wave acceleration in a Hele-Shaw cell,” Shock Waves 28(3), 451–461 (2018)], the simulations are performed in a quasi-two-dimensional cylindrical geometry (Hele-Shaw cell). Parametric studies are carried out to assess the impact of the coefficient of restitution and the strength of the incident shock on the particle jetting behavior. The deposition of vorticity through a multiphase (gas–particle) analog of Richtmyer–Meshkov instability is observed to play a crucial role in channeling the particles into well-defined jets at the outer edge of the particle bed. This is confirmed by the presence of vortex pairs around the outer jets. Furthermore, the effect of the relaxation of the relative velocity between the two phases on the vorticity generation is explored by analyzing the correlation between the radial velocity of particles and the radial velocity of the gas at the particle location.

Shock-induced interfacial instabilities of granular media

“…The number of real particles that represents a computational parcel is quantified using a scaling factor called the superparticle loading, χ , whose value is set based on the volume/mass fraction of the particles and computational memory available. For particle–gas systems, χ reported in previous literature ranges from O(10 1 ) to O(10 3 ) (Osnes et al 2017; Koneru et al 2020; Xue et al 2020). In the present work, χ is of O(10 1 ).…”

“…Numerical simulations were conducted based on CCFD-DPM, a coarse-grained Euler–Lagrange numerical approach suitable for gas– particle flows in laboratory-scale systems (Sundaresan et al 2018; Koneru et al 2020). The CCFD-DPM approach tracks and accounts for parcel–parcel contact interactions.…”

“…Previous experimental and numerical studies found that the momentum imparted to shock-loaded granular columns plays a predominant role in the subsequent jetting structures (Kandan et al 2017; Koneru et al 2020; Xue et al 2020). The imparted momentum strongly depends on the shock strength and the length (mass) of granular columns.…”

“…However, the continuum approximation of granular materials is called into question due to the transient and non-equilibrium coupling between the interstitial gas phase and the particle skeleton in this scenario (Ben-Dor et al 1997; Britan, Shapiro & Ben-Dor 2007; DeMauro et al 2019). Previous studies revealed a complex wave spectrum inside a granular medium impinged head-on by an incident shock wave (Ben-Dor et al 1997; Britan et al 2007; Mo et al 2018, 2019; Koneru et al 2020). Specifically, a much weakened transmitted wave is trailed by a compaction wave propagating through contact points between particles.…”

“…These instabilities have a fundamental bearing on a range of natural phenomena and engineering processes, particularly supernova explosions (Inoue, Yamazaki & Inutsuka 2009), volcanic eruptions (Formenti, Druitt & Kelfoun 2003) and laser-driven inertial confinement fusion experiments (Aglitskiy et al 2010). The resulting particle fingers protruding into gases, reminiscent of the heavy-fluid ‘spikes’ thrusting into a light fluid generated by the conventional Richtmyer–Meshkov instability (RMI) (Luo et al 2019; Li et al 2020; Zhang et al 2020; Zhou et al 2021), inspire investigators to draw a parallel between the shock-driven particle jetting behaviour and the RMI (Vorobieff et al 2011; McFarland et al 2016; Osnes, Vartdal & Pettersson Reif 2017; Fernández-Godino et al 2019; Koneru et al 2020; Duke-Walker et al 2021). Indeed, the shock-driven multiphase instability (SDMI), a variant of the RMI arising from the shock-accelerated perturbed interface between multiphase fluid mixtures of different effective densities, is responsible for the jetting instability of particles that have been explosively dispersed and mixed with gases (Osnes et al 2017; Fernández-Godino et al 2019; Koneru et al 2020).…”