Limits of the potential flow approach to the single-mode Rayleigh-Taylor problem

Document Type

Article

Publication Date

12-1-2006

Abstract

We report on the behavior of a single-wavelength Rayleigh-Taylor flow at late times. The calculations were performed in a long square duct (λ×λ×8λ), using four different numerical simulations. In contradiction with potential flow theories that predict a constant terminal velocity, the single-wavelength Rayleigh-Taylor problem exhibits late-time acceleration. The onset of acceleration occurs as the bubble penetration depth exceeds the diameter of bubbles, and is observed for low and moderate density differences. Based on our simulations, we provide a phenomenological description of the observed acceleration, and ascribe this behavior to the formation of Kelvin-Helmholtz vortices on the bubble-spike interface that diminish the friction drag, while the associated induced flow propels the bubbles forward. For large density ratios, the formation of secondary instabilities is suppressed, and the bubbles remain terminal consistent with potential flow models. © 2006 The American Physical Society.

Identifier

33845757621 (Scopus)

Publication Title

Physical Review E Statistical Nonlinear and Soft Matter Physics

External Full Text Location

https://doi.org/10.1103/PhysRevE.74.066308

e-ISSN

15502376

ISSN

15393755

Issue

6

Volume

74

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