Giant enhancement of hydrodynamically enforced entropic trapping in thin channels

Martens, Steffen; Straube, Arthur V.; Schmid, Gerhard; Schimansky‐Geier, Lutz; Hänggi, Peter

doi:10.1140/epjst/e2014-02321-9

Cited by 11 publications

(15 citation statements)

References 63 publications

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“…The same is true when the flow is generated by a pressure gradient in the solvent These situations require a more detailed modelling regarding the solvent flow field which provides additional advective drag forces to the colloids. For a single particle moving through a constriction, the solvent effect was taken into accout by Martens and coworkers [81,82], for another situation see Ref. [83].…”

Section: Discussionmentioning

confidence: 99%

Flow of colloidal solids and fluids through constrictions: dynamical density functional theory versus simulation

Zimmermann

Smallenburg²,

Löwen³

2016

J. Phys.: Condens. Matter

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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.

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Section: Discussionmentioning

confidence: 99%

Flow of colloidal solids and fluids through constrictions: dynamical density functional theory versus simulation

Zimmermann

Smallenburg²,

Löwen³

2016

J. Phys.: Condens. Matter

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“…This generalized Fick-Jacobs equation, as well as the diffusion equation Eq. ( 2) are solely valid in the absence of external forces, solvent flow [33,34], as well as complex electrochemical potentials [29,30].…”

Section: Rapid Transverse Relaxationmentioning

confidence: 99%

“…Let us illustrate this situation using the classical example of the Langmuir adsorption-desorption process [42,10]. For this particular example, the average adsorption-desorption rate along the pore is given by the well known formula [18,12]: (34) where C bulk represents the mass concentration of the particles at the bulk, and C surf the mass concentration of the particles already adsorbed at the wall. The corresponding rate constants of adsorption and desorption are represented by k ads and k des , respectively.…”

Section: Average Concentration Average Productionmentioning

confidence: 99%

Generalized Fick–Jacobs Approach for Describing Adsorption–Desorption Kinetics in Irregular Pores under Nonequilibrium Conditions

2016

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We present a study exploring the range of applicability of a generalized Fick-Jacobs equation in the case when diffusive mass transport of a fluid along a pore includes chemical reactions in the bulk and pore's surface. The study contemplates nonequilibrium boundary conditions and makes emphasis on the comparison between the predictions coming from the projected Fick-Jacobs description and the corresponding predictions of the original twodimensional mass balance equation, establishing a simple quantitative criterion of validity of the projected description. For the adsorption-desorption process, we demonstrate that the length and the local curvature of the pore are the relevant geometric quantities for its description, allowing for giving very precise predictions of the mass concentration along the pore. Some schematic cases involving adsorption and chemical reaction are used to quantify with detail the concentration profiles in transient and stationary states involving equilibrium and nonequilibrium situations. Our approach provides novel and important insights in the study of diffusion and adsorption in confined geometries.

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“…A number of recent experimental and numerical studies has focused specifically on hydrodynamic effects occurring due to the interplay of confinement and flow [5][6][7][8][9][10][11]. Hydrodynamic effects have also been considered in the context of slit-pores with modulated pore widths [12][13][14][15] and confined active particles [16][17][18]. However, these studies typically consider dilute systems and relatively wide gaps involving a bulk-like region (at zero flow) in the middle region [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Shear-induced laning transition in a confined colloidal film

2017

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Using Brownian dynamics (BD) simulations we investigate a dense system of charged colloids exposed to shear flow in a confined (slit-pore) geometry. The equilibrium system at zero flow consists of three, well-pronounced layers with square-like crystalline in-plane structure. We demonstrate that, for sufficiently large shear rates, the middle layer separates into two sublayers where the particles organize into moving lanes with opposite velocities. The formation of this micro-laned state results in a destruction of the applied shear profile. It has a strong impact not only on the structure of the system, but also on its rheology as measured by the stress tensor. At higher shear rates we observe a disordered state and finally a recrystallization reminiscent of the behavior of bilayer films. We expect the shear-induced laning to be a generic feature of thin films with three or more layers.

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Giant enhancement of hydrodynamically enforced entropic trapping in thin channels

Cited by 11 publications

References 63 publications

Flow of colloidal solids and fluids through constrictions: dynamical density functional theory versus simulation

Flow of colloidal solids and fluids through constrictions: dynamical density functional theory versus simulation

Generalized Fick–Jacobs Approach for Describing Adsorption–Desorption Kinetics in Irregular Pores under Nonequilibrium Conditions

Shear-induced laning transition in a confined colloidal film

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