R. Glynn Holt
Yuren Tian
Xiaoyu Zheng
Robert E. Apfel
Dept. of Mech. Eng., Yale Univ., P.O. Box 2159 Yale Station, New Haven, CT 06520
Utilizing a dedicated acoustic positioning apparatus called the Drop Physics Module (DPM) aboard the First United States Microgravity Laboratory (USML-1) mission, single surfactant-bearing drops were excited into their quadrupole resonance and observed during free decay. Surface shear and dilatational viscosity and Gibb's elasticity are inferred from the frequency and damping measurements using a modification of a previous theory [H.-L. Lu and R. E. Apfel, J. Fluid Mech. 222, 587 (1991)]. Measurements were performed for various combinations of surfactant type, concentration, and drop size. Results from ground-based experiments in ultrasonic fields will also be presented and compared. [Work supported by NASA through JPL Contract No. 958722.]