Kelvin–Helmholtz instability in strongly coupled dusty plasma with rotational shear flows and tracer transport

Abstract

Kelvin–Helmholtz (KH) instability plays a significant role in transport and mixing in various media such as hydrodynamic fluids, plasmas, geophysical flows and astrophysical situations. In this paper, we numerically explore this instability for a two-dimensional strongly coupled dusty plasma medium with rotational shear flows. We study this medium using a generalized hydrodynamic fluid model which treats it as a viscoelastic fluid. We consider the specific cases of rotating vorticity with abrupt radial profiles of rotation. In particular, single-circulation and multi-circulation vorticity shell profiles have been chosen. We observe the KH vortices at each circular interface between two relative rotating flows along with a pair of ingoing and outgoing wavefronts of transverse shear waves. Our studies show that due to the interplay between KH vortices and shear waves in the strongly coupled medium, the mixing and transport behaviour are much better than those of standard inviscid hydrodynamic fluids. In the interest of substantiating the mixing and transport behaviour, the generalized hydrodynamic fluid model is extended to include Lagrangian tracer particles. The numerical dispersion of these tracer particles in a flow provides an estimate of the diffusion in such a medium. We present the preliminary observations of tracer distribution (cluster formation) and diffusion (mean square displacement) across the medium.

Effect of a quasi‐aperiodic substrate on diffusion in a strongly coupled quasi‐one‐dimensional system

“…[24] This results in faster diffusion, resembling strongly coupled systems that exhibit liquid-like behavior. [25] Let us shift our focus to the substrate parameters. According to Figure 3, normal diffusion is observed for L 2 values of 0.85, 1.20, 1.33, and 1.50.…”

“…[ 24 ] This results in faster diffusion, resembling strongly coupled systems that exhibit liquid‐like behavior. [ 25 ]…”

Ring structural transitions in strongly coupled dusty plasmas

“…Depending on the coupling strength [1], the dusty plasma structure can be treated as a fluid [2, 3], a visco-elastic fluid [4][5][6][7], or a crystal [8][9][10][11]. Variations of the coupling strength lead to phase or structure transitions [12][13][14] and control over the growth of instabilities (gravity driven [15,16] and shear driven [17]), turbulence [18][19][20][21], and wave propagation [22][23][24]), etc. In Earth-based experiments, due to the macroscopic size, the dust particles normally levitate close to the lower electrode, in the plasma sheath, where the gravitational force is balanced by the sheath electric force.…”

Magnetized dusty plasma: On issues of its complexity and magnetization of charged dust particles

“…In the last 25 years, a wide spectrum of experimental and theoretical studies has been devoted to explore the collective response of dusty plasma in the form of various dynamical structures/phenomena such as dust acoustic waves, [15,16,[19][20][21][22][23] rotational and vortex motion, [24][25][26][27][28][29][30][31] crystallization and phase transition, [32][33][34][35] instability driven modes, [36][37][38][39][40] and voids. [41][42][43] The major objectives of these theoretical and experimental studies of dusty plasma were to understand the dust-plasma interaction and naturally occurring dusty plasmas, control the nano-to micron-sized dust impurities in semiconductor processing industries, explore the role of impurities on the characteristics of ambient plasma in astrophysical systems, establish it as a model system to understand the complex physical systems at a microscopic level, lower the hazardous effect of solid particles on plasma confinement in fusion devices and resolve the issues of air pollution by particulate of different sizes.…”