We study the flow of two immiscible fluids of different viscosities and equal density through a pipe under a pressure gradient. This problem has a continuum of solutions corresponding to arbitrarily prescribed interface shapes. The question therefore arises as to which of these solutions are stable and thus observable. Experiments have shown a tendency for the thinner fluid to encapsulate the t...

Consideration is given to slow interfacial dynamics in a two-layer system of viscous fluids of comparable density. The fluid flow is governed by the two-dimensional Navier–Stokes equations where it is assumed that the inertial terms can be disregarded. A numerical methodology is presented which allows the study of the dynamics in the nonlinear regime. The numerical method is based on rewriting ...

A linear and weakly nonlinear stability analysis is performed for speci c two-layer systems which have been examined experimentally in Degen et al (Phys Rev E 57, 6647 (1998)). For their water/silicone oil system, at the depth fraction where oscillations are predicted, many wavelengths are unstable. The neutral stability curve is rather at in this region, and oscillations begin slightly above t...

Abstract The instability at the interface between two parallel flows of immiscible liquids through a uniform planar pore is studied by using linear stability analysis. A characteristic equation determines growth rate versus wavenumber, and conditions are determined. governed dimensionless group relating ratio gravity to interfacial tension. Interfacial tension has stabilizing effect resisting d...

In this work, the feasibility of flow pattern and oil hold up the prediction for vertical upward oil–water two–phase flow using pressure fluctuation signals was experimentally investigated. Water and diesel fuel were selected as immiscible liquids. Oil hold up was measured by Quick Closing Valve (QCV) technique, and five flow patterns were identified using high-speed photo...

Biosurfactants are microbial amphiphilic compounds, which can reduce surface tension between two immiscible liquids. Indigenous microbes isolated from raw unprocessed cow’s milk were characterized morphologically and biochemically. The biosurfactant-producing ability of the isolates was determined by hemolytic activity, oil displacement technique their emulsification activity screened against o...

Mixing two immiscible liquids (such as oil and water) using emulsifier and energy inputs has been the matter of study for decades. In early 1890’s extensive work have been carried out on macroemulsions (i.e. oil dispersed in water in the form of fine droplets or vice versa) (Becher, 1977) and several theories and methods of their formation have been vastly explored (Lissant 1976 and 1984). Howe...