Transition stages of Rayleigh–Taylor instability between miscible fluids

“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...

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...

Instability Analysis of Miscible Displacements in Homogeneous Porous Media

Miscible displacement fronts of shear thinning fluids inside rough fractures

The miscible displacement of a shear-thinning fluid by another of same rheological properties is studied experimentally in a transparent fracture by an optical technique imaging relative concentration distributions. The fracture walls have complementary self-affine geometries and are shifted laterally in the direction perpendicular to the mean flow velocity U : the flow field is strongly channe...

Gravity waves at the interface between miscible fluids and at the top of a settling suspension.

Gravity waves were generated at the interface between miscible fluids, or at the top of a settling suspension or a fluidized bed. For these three systems the dispersion relation was measured and compared to the theory and calculated between two buoyant viscous fluids without surface tension. The experimental findings are found to be in good agreement with theory when effective viscosity and vol...