Dynamics of a confined dusty fluid in a sheared ion flow

Abstract

Dynamics of an isothermally driven dust fluid is analyzed which is confined in an azimuthally symmetric cylindrical setup by an effective potential and is in equilibrium with an unconfined sheared flow of a streaming plasma. Cases are analyzed where the confining potential constitutes a barrier for the driven fluid, limiting its spatial extension and boundary velocity. The boundary effects entering the formulation are characterized by applying the appropriate boundary conditions and a range of solutions exhibiting single and multiple vortex are obtained. The equilibrium solutions considered in the cylindrical setup feature a transition from single to multiple vortex state of the driven flow. Effects of (i) the variation in dust viscosity, (ii) coupling between the driving and the driven fluid, and (iii) a friction determining the equilibrium dynamics of the driven system are characterized.

Structural transition of vortices to nonlinear regimes in a dusty plasma

“…In these regimes, the dust fluid flows within the velocity range of 1 − 50 mm/sec, while the dust acoustic speed c ds is found to be 12 cm/sec in the domain. As observed in the earlier analysis [3,4], the flow structure in the linear regime is characterized by a system of symmetric and elongated circulations (or streamlines that are aligned with the confining boundaries) as shown in Fig. 5 (2 nd coulum).…”

“…The validity of the present numerical solution is verified by comparing the flow profiles produced by the previous analytical solution in the linear limit [3]. Improving from the earlier analysis [3,4], this model has the freedom of choosing any form of the driving flows, confining boundaries, and arbitrary Reynolds number regimes. The vortex structure of the steady dust fluid in the poloidal cross-section is analyzed within the transition range of Reynolds number 0.001 < Re ≤ 50 where the dust flow with speed ranges from 0.1 mm to 3 cm while the dust acoustic speed is about 12 cm/sec.…”

“…For easy comparison with the analytic solutions presented in [3,4], we have used the identical conditions as the typical laboratory glow discharge argon plasma with micron-sized dust. The plasma parameters are n ≃…”

Overestimation of Viscosity by the Green-Kubo Method in a Dusty Plasma Experiment

“…As it does in fluids, viscosity in plasmas affects instabilities [10], waves [11][12][13], vortices [14], and heating [15]. Despite these similarities, plasmas have unusual viscosity properties because the underlying Coulomb forces have a long range, unlike the short-range interactions typical of liquids and gases.…”

Experimental observation of self excited co-rotating multiple vortices in a dusty plasma with inhomogeneous plasma background

“…The horizontal and vertical vortex motion of dust grains in the presence of an auxiliary electrode near the levitated dust cloud in capacitive coupled plasma is also reported by Samarian et al 21 and Law et al 22 . The rotation or vortex motion of the dust particulates in the absence of magnetic field can be induced by asymmetric ions flow or sheared flow along with electric field 11,23,24 , charge gradient of the particles along with the non-electrostatic forces 19,[25][26][27] , RayleighTaylor instability 28 and transient shear instability 29 .…”