Giant unilamellar vesicles (GUVs) are good models of living cells, owing to their size and lamellarity. Compartmentalization within lipid vesicles has been exploited for the study of membrane behavior, lipid mechanics and a variety of biological processes, though their synthesis is not straightforward. We describe the development of a stratified flow driven microfluidic approach to GUV assembly...

We have performed laboratory experiments to study wave generation over and in the lee of model topography. We have chosen to use periodic, finite-amplitude hills which are representative of the Earth’s major mountain ranges as well as the repetitious topographic features of the ocean floor. The topographic shapes are selected to encompass varying degrees of roughness, from smoothly-varying sinu...

In this paper, we give an explicit asymptotic construction of a class of solitary waves, widely known as gap-solitons in other physical contexts, for a certain three-layered fluid flow. The essential ingredients are the existence of a spectral gap between two branches of the dispersion relation, and the development of a set of envelope equations to describe weakly nonlinear waves, whose carrier...

A layer of granular material on a vertically vibrating sawtooth-shaped base exhibits horizontal flow whose speed and direction depend on the parameters specifying the system in a complex manner. Discrete-particle simulations reveal that the induced flow rate varies with height within the granular layer and oppositely directed flows can occur at different levels. The behavior of the overall flow...

The notion of over-reflection has been used to rationalize the linear instability of shear flows that are directed and sheared in a horizontal plane but stratified and subject to rotation in the vertical. In the linear stability analysis of these types of flows, two types of critical levels may appear that translate to singular points in the corresponding differential eigenvalue problem. The fi...

The growth of secondary vortices on the braids separating Kelvin–Helmholtz billows is investigated via numerical simulations. The similarity theory of Corcos & Sherman (1976) is extended to include mixing processes with Prandtl number greater than unity, and is shown to provide a useful description of the physics of the braid regions just prior to the onset of secondary instability. The numeric...

Water stratified thermally or with dissolved material has a refractive index that varies with height. The stratification has no obvious visual effect until the fluid is disturbed, for example by a fish, but then it marks the creature's wake with a jump in refractive index that is visible in shadowgraphic projection. Two shadowgraphs in stereo display the wake in three dimensions. For a permanen...

Two-dimensional simulations of flow instability at the interface of a two-layer, density-matched, viscosity-stratified Poiseuille flow are performed using a front-tracking/finite difference method. We present results for the small-amplitude (linear) growth rate of the instability at small to medium Reynolds number for varying thickness ratio n, viscosity ratio m, and wavenumber. We also present...

The simplifications required to apply the Boussinesq approximation to compressible flow are compared with those in an incompressible fluid. The larger degree of approximation required to describe mass conservation in a stratified compressible fluid with the Boussinesq continuity equation has led to the development of several different sets of “anelastic” equations that may be regarded as genera...

We study two-dimensional flow in a layered heterogeneous medium composed of two materials whose hydraulic properties and spatial distribution are known statistically but are otherwise uncertain. Our analysis relies on the composite media theory, which employs random domain decomposition in the context of groundwater flow moment equations to explicitly account for the separate effects of materia...