Dynamics of colloids in a narrow channel driven by a nonuniform force

Abstract

Using Brownian dynamics simulations, we investigate the dynamics of colloids confined in two-dimensional narrow channels driven by a nonuniform force Fdr(y) . We considered linear-gradient, parabolic, and deltalike driving-force profiles. This driving force induces melting of the colloidal solid (i.e., shear-induced melting), and the colloidal motion experiences a transition from elastic to plastic regime with increasing Fdr. For intermediate Fdr (i.e., in the transition region) the response of the system, i.e., the distribution of the velocities of the colloidal chains upsiloni(y) , in general does not coincide with the profile of the driving force Fdr(y), and depends on the magnitude of Fdr, the width of the channel, and the density of colloids. For example, we show that the onset of plasticity is first observed near the boundaries while the motion in the central region is elastic. This is explained by: (i) (in)commensurability between the chains due to the larger density of colloids near the boundaries, and (ii) the gradient in Fdr. Our study provides a deeper understanding of the dynamics of colloids in channels and could be accessed in experiments on colloids (or in dusty plasma) with, e.g., asymmetric channels or in the presence of a gradient potential field.

Tunable diffusion of magnetic particles in a quasi-one-dimensional channel

“…Furthermore, q1D systems can be used as models for the study of collective phenomena in low dimensional systems, e.g, vortex matter in type-II superconductors [43,44], colloidal particles [45,46] and dusty plasmas. In addition, the mechanisms of ion transport in narrow channels [47] and DNA manipulation using magnetic particles [48,49] can be studied by modelling q1D systems.…”

Single-file diffusion in periodic energy landscapes: The role of hydrodynamic interactions

“…Collective diffusion is a dynamic process related to the cooperative movements of many particles that lead and promote collective and faster diffusion of particles in the line. We should note, interestingly, that similar collective diffusion is observed at long times in finite-size systems, i.e., circular channels, composed of particles interacting with long-range potentials and where HIs are not present [17,37]. To better understand the effects of HIs on the diffusion of particles along the line, we also compute the exponent α and the mobility factor F , where the MSD can be approximated, with a high accuracy, by the power-law relation given by Eq.…”

“…Furthermore, when the suspension is confined, it shows new features that are not found in the bulk. For instance, in highly restricted geometries, such as quasi-one-dimensional (q1D) and one-dimensional (1D) systems, the long-time mean-square displacement (MSD) follows a subdiffusive non-Fickian behavior, i.e., W (t) ∝ t α , with α < 1 [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

“…During the last decade, the influence of interparticle interactions on the SFD of 1D colloidal suspensions has been discussed extensively using experiments, simulations, and theory [2][3][4][5][6][7][8][9]11,[13][14][15][16][17][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. However, as far as we know, the effects of HIs on the SFD have seldom been studied [26].…”

Absolute cross sections of ultra-soft x-ray radiation in electron scattering upon atoms and the soft-photons approximation

“…Since, as already noted, the greatest discrepancy between the experimental data presented in [5,9] and the theory is exists in the small photon energies region, the data obtained in Refs. [16,17] are of particular interest. These works present results of absolute, not relative, as in [1], measurements of BS cross sections values for ultrasoft x-ray photons (λ = 7..18 nm) generated in scattering of electrons with energies of 0.4..2 keV on Ar, Kr, and Xe atoms.…”