Flow of colloidal solids and fluids through constrictions: dynamical density functional theory versus simulation. (26th April 2016)

• Record Type: Journal Article
• Authors: Zimmermann, Urs; Smallenburg, Frank; Löwen, Hartmut
• Is Part Of: Journal of physics. Volume 28:Number 24(2016)
• Publication Date: 2016-04-26
• Subjects: density functional theory -- dynamical density functional theory -- confinement -- non-equilibrium -- Brownian dynamics simulations; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/0953-8984/28/24/244019
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: Using both dynamical density functional theory and particle-resolved Brownian dynamics simulations, we explore the flow of two-dimensional colloidal solids and fluids driven through a linear channel with a constriction. The flow is generated by a constant external force acting on all colloids. The initial configuration is equilibrated in the absence of flow and then the external force is switched on instantaneously. Upon starting the flow, we observe four different scenarios: a complete blockade, a monotonic decay to a constant particle flux (typical for a fluid), a damped oscillatory behaviour in the particle flux, and a long-lived stop-and-go behaviour in the flow (typical for a solid). The dynamical density functional theory describes all four situations but predicts infinitely long undamped oscillations in the flow which are always damped in the simulations. We attribute the mechanisms of the underlying stop-and-go flow to symmetry conditions on the flowing solid. Our predictions are verifiable in real-space experiments on magnetic colloidal monolayers which are driven through structured microchannels and can be exploited to steer the flow throughput in microfluidics.