A numerical study of three-dimensional bubble merger in the Rayleigh{endash}Taylor instability
- Department of Mathematical Sciences, Indiana University---Purdue University at Indianapolis, Indianapolis, Indiana 46202 (United States)
The Rayleigh{endash}Taylor instability arises when a heavy fluid adjacent to a light fluid is accelerated in a direction against the density gradient. Under this unstable configuration, a perturbation mode of small amplitude grows into bubbles of the light fluid and spikes of the heavy fluid. Taylor discovered the steady state motion with constant velocity for a single bubble or periodic bubbles in the Rayleigh{endash}Taylor instability. Read and Youngs studied the motion of a randomly perturbed fluid interface in the Rayleigh{endash}Taylor instability. They reported constant acceleration for the overall bubble envelope. Bubble merger is believed to cause the transition from constant velocity to constant acceleration. In this paper, we present a numerical study of this important physical phenomenon. It analyzes the physical process of bubble merger and the relationship between the horizontal bubble expansion and the vertical interface acceleration. A dynamic bubble velocity, beyond Taylor{close_quote}s steady state value, is observed during the merger process. It is believed that this velocity is due to the superposition of the bubble velocity with a secondary subharmonic unstable mode. The numerical results are compared with experiments. {copyright} {ital 1996 American Institute of Physics.}
- OSTI ID:
- 434517
- Journal Information:
- Physics of Fluids (1994), Journal Name: Physics of Fluids (1994) Journal Issue: 2 Vol. 8; ISSN PHFLE6; ISSN 1070-6631
- Country of Publication:
- United States
- Language:
- English
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