### ASA 125th Meeting Ottawa 1993 May

## 1pPA11. Oscillations of a deformed drop in an acoustic field.

**T. Shi
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Robert E. Apfel
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*Dept. of Mech. Eng., P.O. Box 2159, Yale Univ., New Haven, CT 06520
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Because of the importance of acoustic levitation technology and no
existing theory of oscillations of deformed drops in acoustic fields, a
boundary integral technique, developed by Baker et al. [J. Fluid Med. 123,
477--501 (1982)], has been modified to study oscillations of axisymmetric
liquid drops in air. The method consists of determining evolution equations for
the position and velocity potential on the surface of the drop. The motion of
the surface is determined from the potential by solving an integral equation.
The potential is updated every time step by using the Bernoulli equation that
depends on gravity, interfacial tension force, and acoustic radiation pressure.
The acoustic field is determined for every time step by the Fourier
transformation method developed by us. Given initial position and potential
along the drop surface, the drop will oscillate around its equilibrium
positions where it is statically deformed, which can be computed by introducing
numerical damping. Some results on oscillations and frequencies of acoustically
deformed drops will be presented. [Work supported by NASA through JPL Contract
No. 958722.]