The drop dynamics experiments utilized the unique zero-g environment provided by space flight to investigate the nonlinear dynamic behavior of free drops. These experiments are natural candidates for implementation in a manned space flight. Astronauts volunteered their own free time to conduct additional experimental runs. making the experiments successful. The USML-2 flight was aimed at completing the experimental series originally scheduled for USML-1, which were not completed because of hardware malfunction. The past experience helped us in designing the USML-2 experiments, taking into account the limitations of the experimental hardware. It also prepared us to anticipate extensive data reduction and processing activities. The USML-2 experiments had three primary objectives:
- Equilibrium shapes of liquid drops under the effects of rotation and acoustic flattening: The USML-2 experiments showed that a rotating liquid drop bifurcates into two-lobed shapes at a lower angular velocity if it is flattened. We have conducted a systematic study of the flattening effects on rotation bifurcation.
- Core-centering of compound drops in capillary oscillations: The USML-1 experiments showed the effect of oscillations on core-centering. In USML-2 we pushed the experimental parameters into regions unexplored by theory.
- Nonlinear drop oscillations: a) Mode coupling: In this experiment we have observed energy transfer between the oscillation modes. b) Hysteresis and jump: We have observed weak softening hysteresis effects in our experiments. This can be described by Duffing-like sets of equations. c) Chaotic drop oscillations: Chaotic oscillations of a drop driven by multi-frequency excitation has been observed. Detailed analysis is underway.
Second United States Microgravity Laboratory: One Year Report
Wang, T. G., Anilkumar, A. V., Lee, C. P., Hmelo, A. B., & Daidzic, N. (1998). Experiment IV: USML-2 drop dynamics experiment. In M. Vlasse, D. McCauley, & C. Walker (Eds.), Second United States Microgravity Laboratory: One Year Report, Volume 1 (pp. 4-63-4-136). National Aeronautics and Space Administraiton. https://ntrs.nasa.gov/citations/19990018868