title: Shape relaxation of liquid drops in a microgravity environment.
abstract: We investigated shape relaxation of liquid drops in a microgravity environment that was created by letting the drops fall freely. The drops were initially levitated in air by an acoustic/electrostatic hybrid levitator. The levitated drops were deformed due to the force balance among the levitating force, surface tension, and gravity. During the free fall, the deformed drops underwent shape relaxation driven by the surface tension to restore a spherical shape. The progress of the shape relaxation was characterized by measuring the aspect ratio as a function of time, and was compared to a simple linear relaxation model (in which only the fundamental mode was considered) for perfectly conductive drops. The results show that the model quite adequately describes the shape relaxation of uncharged/charged drops released from an acoustically levitated state. However, the model is less successful in describing the relaxation of drops that were levitated electrostatically before the free fall. This may be due to finite electrical conductivities of liquids, which somehow affects the initial stage of the shape relaxation process.
authors.affiliation: University of Southern California, Los Angeles, CA 90089-1453, USA. sadhal@usc.edu
authors.forename: S S
authors.initials: SS
authors.lastname: Sadhal
authors.forename: A
authors.initials: A
authors.lastname: Rednikov
authors.forename: K
authors.initials: K
authors.lastname: Ohsaka
mesh_terms: D000162:Acoustics; D003198:Computer Simulation; D004777:Environment; D006112:Gravitation; D019563:Mechanics; D008962:Models, Theoretical; D009068:Movement; D010825:Physics / Q000379:methods*; D055672:Static Electricity; D013997:Time Factors; D014893:Weightlessness