INTERFACIAL DYNAMICS OF 2 LIQUIDS UNDER AN OSCILLATING GRAVITATIONAL-FIELD

The evolution of two miscible liquids meeting at an initially sharp interface inside a cavity under microgravity g-jitter conditions is studied numerically. We show the response of the interface and kinematics of the flowfield to various g-jitter accelerations and aspect ratio variations. The interface region acts like a vortex source sheet, and it can be unstable to Kelvin-Helmholtz and Rayleigh-Taylor instabilities. The vortices produced along the interface can serve as a stirring mechanism to promote local mixing. Below the critical Stokes-Reynolds number, the destabilization of the interface results in deformation into wavy structures. In some parameter regions, these structures oscillate in time; in others, they are quasisteady. Above the critical Stokes-Reynolds number, “chaotic” instability results and the interface breaks into concentration pockets. The morphology of the initial breakup is similar to observed Rayleigh-Taylor instability. Subsequent mixing of the two fluids after the breakup of the interface is then very rapid. © 1990 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.