Accession Number : ADA262895

Title :   On the Nonlinear Interfacial Instability of Rotating Core-Annular Flow.

Descriptive Note : Contractor rept.,

Corporate Author : INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA

Personal Author(s) : Coward, Aidrian V. ; Hall, Philip

Report Date : FEB 1993

Pagination or Media Count : 40

Abstract : The interfacial stability of rotating core-annular flows is investigated. The linear and nonlinear effects are considered for the case when the annular region is very thin. Both asymptotic and numerical methods are used to solve the flow in the core and film regions which are coupled by a difference in viscosity and density. The long-time behaviour of the fluid-fluid interface is determined by deriving its nonlinear evolution in the form of a modified Kuramoto-Sivashinsky equation. We obtain a generalization of this equation to three dimensions. The flows considered are applicable to a wide array of physical problems where liquid films are used to lubricate higher or lower viscosity core fluids, for which a concentric arrangement is desired. Linearized solutions show that the effects of density and viscosity stratification are crucial to the stability of the interface. Rotation generally destabilizes non-axisymmetric disturbances to the interface, whereas the centripetal forces tend to stabilize flows in which the film contains the heavier fluid. Nonlinear affects allow finite amplitude helically travelling waves to exist when the fluids have different viscosities.... Core-annular flows, Interfacial instability.

Descriptors :   *ANNULAR FLOW, *FLUID FLOW, *VISCOUS FLOW, AMPLITUDE, AXISYMMETRIC, DENSITY, FLUIDS, INSTABILITY, INTERFACES, LIQUIDS, ROTATION, STABILITY, STRATIFICATION, VISCOSITY, NUMERICAL METHODS AND PROCEDURES, THIN FILMS, LUBRICANTS, PLATES, WATER WAVES, AIR WATER INTERACTIONS, SURFACE TENSION, WIND.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE