Mapping diffusivity of narrow channels into one-dimension

基于扩散率演化解密扩散的非高斯性

Deciphering Non-Gaussianity of Diffusion Based on the Evolution of Diffusivity

本文通过扩散率时空演化解密反常扩散中的非高斯性，结合实验与模拟证明非高斯性可由扩散率分布预测，并由有效Péclet数决定尾部分布的扩展或收缩。

Active Brownian motion in a narrow channel

We review recent advances in rectification control of artificial microswimmers, also known as Janus particles, diffusing along narrow, periodically corrugated channels. The swimmer self-propulsion mechanism is modeled so as to incorporate a nonzero torque (propulsion chirality). We first summarize the effects of chirality on the autonomous current of microswimmers freely diffusing in channels of different geometries. In particular, left-right and upside-down asymmetric channels are shown to exhibit different transport properties. We then report new results on the dependence of the diffusivity …

Anisotropic diffusion of spherical particles in closely confining microchannels

We present here the measurement of the diffusivity of spherical particles closely confined by narrow microchannels. Our experiments yield a two-dimensional map of the position-dependent diffusion coefficients parallel and perpendicular to the channel axis with a resolution down to 129 nm. The diffusivity was measured simultaneously in the channel interior, the bulk reservoirs, as well as the channel entrance region. In the channel interior we found strongly anisotropic diffusion. While the perpendicular diffusion coefficient close to the confining walls decreased down to approximately 25% of t…

粒子-壁面的取向相互作用与活性布朗粒子通过窄通道的扩散

Particle-Wall Alignment Interaction and Active Brownian Diffusion Through Narrow Channels

该研究通过数值模拟探究粒子-壁面取向相互作用对活性粒子通过窄通道扩散的影响，明确不同稳定取向构型下扩散系数的变化规律，为理解微/纳米物体在窄通道中的扩散提供理论支撑。

Mapping between long-time molecular and Brownian dynamics

We use computer simulations to test a simple idea for mapping between long-time self diffusivities obtained from molecular and Brownian dynamics. The strategy we explore is motivated by the behavior of fluids comprising particles that interact via inverse-power-law pair potentials, which serve as good reference models for dense atomic or colloidal materials. Based on our simulation data, we present an empirical expression that semi-quantitatively describes the "atomic" to "colloidal" diffusivity mapping for inverse-power-law fluids, but also for model complex fluids with considerably softer (s…

Hydrodynamic and entropic effects on colloidal diffusion in corrugated channels

In the absence of advection, confined diffusion characterizes transport in many natural and artificial devices, such as ionic channels, zeolites, and nanopores. While extensive theoretical and numerical studies on this subject have produced many important predictions, experimental verifications of the predictions are rare. Here, we experimentally measure colloidal diffusion times in microchannels with periodically varying width and contrast results with predictions from the Fick-Jacobs theory and Brownian dynamics simulation. While the theory and simulation correctly predict the entropic effec…