Resources

Author(s): Wankun Liu and Jang Min Park The interaction between two immiscible droplets in a confined shear flow is studied numerically by using a ternary diffuse-interface model. Three different types of interaction are observed: (1) reverse motion, (2) pass-over motion, and (3) rotary Janus motion after wetting. We investigate the effects of initial droplet position, capillary number, and confinement on the droplet trajectory and the deformation...

Author(s): Yoav Green The nanofluidic paradigm that low-concentration conductance is concentration-independent has recently come under scrutiny. Recent works have shown that the conductance depends on the concentration and that the slope, α, ranges between 0 and 1/2. However, experiments have also measured slopes of 2/3 and 1. In this work an analytical solution for the conductance is derived that accounts for surface charge regulation (SCR),...

Author(s): Kunlin Ma, Nimish Pujara, and Jean-Luc Thiffeault The trajectories of microswimmers, such as plankton or artificial active particles, are altered by their interactions with the ambient flow. We show here that microswimmers swimming beneath surface gravity waves can resurface or swim to deep depths depending on their coupling to the flow. We obtain a system of equations describing wave-averaged microswimmer trajectories, from which we...

Author(s): Yuan Luo, Yipeng Shi, and Charles Meneveau Small scale intermittency is ubiquitous in turbulent flows. Many features of small-scale motions can be described by the velocity gradient tensor (VGT) for which the nonlinear term in the Navier-Stokes equations (NSE) is a source of strong fluctuations. The figure shows intermittent time signals of longitudinal VGT elements along Lagrangian trajectories from five levels of a recently proposed...

Author(s): Henrik Nordanger, Alexander Morozov, and Joakim Stenhammar Tracers immersed in suspensions of microswimmers such as bacteria or algae display several phenomena unseen in equilibrium systems, including strongly enhanced diffusivity relative to the Brownian value. Previous theoretical studies have focussed on spherical tracers undergoing isotropic diffusion. Here, we present a computational model of ellipsoidal tracer particles undergoing...

Author(s): Mary A. Joens and James W. Swan Unsteady translation of a sphere in a viscoelastic fluid is studied analytically. General, fully invertible relationships between an imposed time-dependent velocity and the resultant force are described in terms of a Volterra series expansion. These results are used to analyze particle motion in fluids described by the Johnson-Segalman and Giesekus models and to define a general framework for analyzing...

Author(s): Jens P. Metzger, Christopher P. McLaren, Sebastian Pinzello, Nicholas A. Conzelmann, Christopher M. Boyce, and Christoph R. Müller A granular droplet that is composed of smaller and denser particles in a bed of larger and lighter particles is found to sink and split when subjected to a combination of vibration and fluidizing gas flow. Despite visual similarities with fluid-like instabilities, the observed phenomenon is a result of the...