Oscillations of confined fibers transported in microchannels

受限在方形微通道中的弹性珠的运动与流体动力阻力

Motion and hydrodynamic resistance of an elastic bead confined in a square microchannel

针对软颗粒在受限几何结构中流动时弹性变形诱导额外压降的物理参数未知问题，本文通过实验测量并结合模拟提出力平衡模型，将力测量结果归纳为单一标度律并提供物理见解。

Capillary Flow of Oil in a Single Foam Microchannel

When using appropriate surfactants, oil and aqueous foam can be intimately mixed without the foam being destroyed. In this Letter, we show that a foam, initially free of oil, can draw an oil drop under the action of capillary forces and stretch it through the aqueous network. We focus on the suction of oil by a single horizontal foam channel, known as a Plateau border. In such confined channels, imbibition dynamics are governed by a balance between capillarity and viscosity. Yet, the scaling law for our system differs from that of classical imbibition in porous media such as aqueous foam. This…

Transport of flexible fibers in confined micro-channels

When transported in confined geometries rigid fibers show interesting transport dynamics induced by friction with the top and bottom walls. Fiber flexibility causes an additional coupling between fiber deformation and transport and is expected to lead to more complex dynamics. A first crucial step for their understanding is the characterization of the deformed fiber shape. Here we characterize this shape for a fiber transported in a confined plug flow perpendicular to the flow direction using a combination of microfluidic experiments and numerical simulations. In the experiments, size, initial…

圆柱形微通道中微型游泳者的运动

Motion of microswimmers in cylindrical microchannels

提出类似squirmer的模型研究圆柱形微通道中微型游泳者的运动，发现推进力随约束增强而增加，但游泳速度始终低于无约束状态，不同游泳模式对死胡同推进力影响显著。

Fiber buckling in confined viscous flows: an absolute instability described by the Ginzburg-Landau equation

We explore the dynamics of a flexible fiber transported by a viscous flow in a Hele-Shaw cell of height comparable to the fiber height. We show that long fibers aligned with the flow experience a buckling instability. Competition between viscous and elastic forces leads to the deformation of the fiber into a wavy shape convolved by a Bell-shaped envelope. We characterize the wavelength and phase velocity of the deformation as well as the growth and spreading of the envelope. Our study of the spatio-temporal evolution of the deformation reveals a linear and absolute instability arising from a l…

Controlling transport dynamics of confined asymmetric fibers

Transport properties of particles in confining geometries show very specific characteristics as lateral drift, oscillatory movement between lateral walls or the deformation of flexible fibers. These dynamics result from viscous friction with transversal and lateral channel walls inducing strong flow perturbations around the particles that act like moving obstacles. In this paper, we modify the fiber shape by adding an additional, small fiber arm, which leads to T and L shaped fibers with only one or, respectively, zero symmetry axes and investigate the transport properties. For this purpose, w…