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Title: Visco-elastic fluid simulations of coherent structures in strongly coupled dusty plasma medium

Abstract

A generalized hydrodynamic model depicting the behaviour of visco-elastic fluids has often been invoked to explore the behaviour of a strongly coupled dusty plasma medium below their crystallization limit. The model has been successful in describing the collective normal modes of the strongly coupled dusty plasma medium observed experimentally. The paper focuses on the study of nonlinear dynamical characteristic features of this model. Specifically, the evolution of coherent vorticity patches is being investigated here within the framework of this model. A comparison with Newtonian fluids and molecular dynamics simulations treating the dust species interacting through the Yukawa potential has also been presented.

Authors:
; ;  [1]
  1. Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)
Publication Date:
OSTI Identifier:
22304109
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPARATIVE EVALUATIONS; CRYSTALLIZATION; FLUIDS; HYDRODYNAMIC MODEL; MOLECULAR DYNAMICS METHOD; NONLINEAR PROBLEMS; PLASMA; SIMULATION; YUKAWA POTENTIAL

Citation Formats

Singh Dharodi, Vikram, Kumar Tiwari, Sanat, and Das, Amita, E-mail: amita@ipr.res.in. Visco-elastic fluid simulations of coherent structures in strongly coupled dusty plasma medium. United States: N. p., 2014. Web. doi:10.1063/1.4888882.
Singh Dharodi, Vikram, Kumar Tiwari, Sanat, & Das, Amita, E-mail: amita@ipr.res.in. Visco-elastic fluid simulations of coherent structures in strongly coupled dusty plasma medium. United States. doi:10.1063/1.4888882.
Singh Dharodi, Vikram, Kumar Tiwari, Sanat, and Das, Amita, E-mail: amita@ipr.res.in. Tue . "Visco-elastic fluid simulations of coherent structures in strongly coupled dusty plasma medium". United States. doi:10.1063/1.4888882.
@article{osti_22304109,
title = {Visco-elastic fluid simulations of coherent structures in strongly coupled dusty plasma medium},
author = {Singh Dharodi, Vikram and Kumar Tiwari, Sanat and Das, Amita, E-mail: amita@ipr.res.in},
abstractNote = {A generalized hydrodynamic model depicting the behaviour of visco-elastic fluids has often been invoked to explore the behaviour of a strongly coupled dusty plasma medium below their crystallization limit. The model has been successful in describing the collective normal modes of the strongly coupled dusty plasma medium observed experimentally. The paper focuses on the study of nonlinear dynamical characteristic features of this model. Specifically, the evolution of coherent vorticity patches is being investigated here within the framework of this model. A comparison with Newtonian fluids and molecular dynamics simulations treating the dust species interacting through the Yukawa potential has also been presented.},
doi = {10.1063/1.4888882},
journal = {Physics of Plasmas},
number = 7,
volume = 21,
place = {United States},
year = {Tue Jul 15 00:00:00 EDT 2014},
month = {Tue Jul 15 00:00:00 EDT 2014}
}
  • The strongly coupled dusty plasma has often been modelled by the Generalized Hydrodynamic (GHD) model used for representing visco-elastic fluid systems. The incompressible limit of the model which supports transverse shear wave mode is studied in detail. In particular, dipole structures are observed to emit transverse shear waves in both the limits of sub- and super-luminar propagation, where the structures move slower and faster than the phase velocity of the shear waves, respectively. In the sub-luminar limit the dipole gets engulfed within the shear waves emitted by itself, which then backreacts on it and ultimately the identity of the structuremore » is lost. However, in the super-luminar limit the emission appears like a wake from the tail region of the dipole. The dipole, however, keeps propagating forward with little damping but minimal distortion in its form. A Poynting-like conservation law with radiative, convective, and dissipative terms being responsible for the evolution of W, which is similar to “enstrophy” like quantity in normal hydrodynamic fluid systems, has also been constructed for the incompressible GHD equations. The conservation law is shown to be satisfied in all the cases of evolution and collision amidst the nonlinear structures to a great accuracy. It is shown that monopole structures which do not move at all but merely radiate shear waves, the radiative term, and dissipative losses solely contribute to the evolution of W. The dipolar structures, on the other hand, propagate in the medium and hence convection also plays an important role in the evolution of W.« less
  • We report on experimental evidence of visco-elastic effects in a strongly coupled dusty plasma through investigations of the propagation characteristics of low frequency dust acoustic waves and by excitations of transverse shear waves in a DC discharge Argon plasma.
  • The Kelvin-Helmholtz (KH) instability in the context of strongly coupled dusty plasma medium has been investigated. In particular, the role of transverse shear and the compressional acoustic modes in both the linear and nonlinear regimes of the KH instability has been studied. It is observed that in addition to the conventional nonlocal KH instability, there exists a local instability in the strong coupling case. The interplay of the KH mode with this local instability shows up in the simulations as an interesting phenomenon of recurrence in the nonlinear regime. Thus, a cyclic KH instability process is observed to occur. Thesemore » cyclic events are associated with bursts of activity in terms of transverse and compressional wave generation in the medium.« less
  • We give a theoretical investigation on the dynamics of nonlinear electrostatic waves in a strongly coupled dusty plasma with strong electrostatic interaction between dust grains in the presence of the polarization force (i.e., the force due to the polarized Debye sheath). Adopting a reductive perturbation method, we derived a three-dimensional Kadomtsev-Petviashvili equation that describes the evolution of weakly nonlinear electrostatic localized waves. The energy integral equation is used to study the existence domains of the localized structures. The analysis provides the localized structure existence region, in terms of the effects of strong interaction between the dust particles and polarization force.
  • The existence and evolution of soliton-like structures in a dusty plasma medium are investigated in a first principles approach using molecular dynamic (MD) simulations of particles interacting via a Yukawa potential. These localized structures are found to exist in both weakly and strongly coupled regimes with their structures becoming sharper as the correlation effects between the dust particles get stronger. A surprising result, compared to fluid simulations, is the existence of rarefactive soliton-like structures in our non-dissipative system, a feature that arises from the charge conjugation symmetry property of the Yukawa fluid. Our simulation findings closely resemble many diverse experimentalmore » results reported in the past.« less