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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:

  1. 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.
  2. 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.
  3. 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.



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Second United States Microgravity Laboratory: One Year Report



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