Concentration-dependent diffusion instability in reactive miscible fluids

Concentration-dependent diffusion instability in reactive miscible fluids.

We report on chemoconvective pattern formation phenomena observed in a two-layer system of miscible fluids filling a vertical Hele-Shaw cell. We show both experimentally and theoretically that the concentration-dependent diffusion coupled with frontal acid-base neutralization can give rise to the formation of a local unstable zone low in density, resulting in a perfectly regular cell-type conve...

Viscous Fingering in Miscible, Immiscible and Reactive Fluids

With the Lattice Boltzmann method (using the BGK approximation) we investigate the dynamics of Hele-Shaw flow under conditions corresponding to various experimental systems. We discuss the onset of the instability (dispersion relation), the static properties (characterization of the interface) and the dynamic properties (growth of the mixing zone) of simulated Hele-Shaw systems. We examine the ...

“Transition Stages of Rayleigh-Taylor Instability Between Miscible Fluids” Andrew W. Cook and Paul E. Dimotakis Transition stages of Rayleigh-Taylor instability between miscible fluids∗

Direct Numerical Simulations (DNS) have been performed of three-dimensional, Rayleigh-Taylor instability (RTI) between two incompressible, miscible fluids, with a 3:1 density ratio. Periodic boundary conditions are imposed in the horizontal directions of a rectangular domain, with no-slip top and bottom walls. Solutions are obtained for the Navier-Stokes equations, augmented by a species transp...

Instability Analysis of Miscible Displacements in Homogeneous Porous Media

Concentration dependent diffusion of self-propelled rods.

We examine the persistent random motion of self-propelled rods (SPR) as a function of the area fraction phi and study the effect of steric interactions on their diffusion properties. SPR of length l and width w are fabricated with a spherocylindrical head attached to a beaded chain tail, and show directed motion on a vibrated substrate. The mean square displacement (MSD) on the substrate grows ...