Elastic instability in stratified core annular flow

Non-Axisymmetric Instability of Core-Annular Flow

Stability of core-annular flow of water and oil in a vertical circular pipe is studied with respect to nonaxisymmetric disturbances. Results show that when the oil core is thin, the flow is most unstable to the asymmetric sinuous mode of disturbance, and the core moves in the form of corkscrew waves as observed in experiments. The asymmetric mode of disturbance is the most dangerous mode for qu...

Forced instability of core-annular flow in capillary constrictions

Radiation Instability in a Stratified Shear Flow

The paper deals with a new mechanism of instability in stratified fluid caused by internal wave radiation from a shear layer. This radiation instability may be explained in terms of the negativeenergy wave concept. These waves are able to grow due to radiation losses. The dispersion relation and non-linear stage of the process are analyzed through a model with tangential velocity discontinuity....

Corrugated interfaces in multiphase core-annular flow

Microfluidic devices can be used to produce highly controlled and monodisperse double or multiple emulsions. The presence of inner drops inside a jet of the middle phase introduces deformations in the jet, which leads to breakup into monodisperse double emulsions. However, the ability to generate double emulsions can be compromised when the interfacial tension between the middle and outer phase...

Instability criterion for oblique modes in stratified circular Couette flow

An analytical approach is carried out that provides an inviscid stability criterion for the strato-rotational instability (in short SRI) occurring in a Taylor-Couette system. The control parameters of the problem are the rotation ratio μ and the radius ratio η. The study is motivated by recent experimental [1] and numerical [2, 3] results reporting the existence of unstable modes beyond the Ray...