Neil A. Bhargava
Dept. of Mech. Eng., Yale Univ., P.O. Box 202778, New Haven, CT 06520
This simulation was written in order to describe the behavior in two dimensions of a liquid droplet inside the drop physics module (DPM). The DPM is a chamber which uses standing sound waves in order to levitate and position a liquid droplet placed within it. The translational motion of the liquid droplet in this acoustic field can be described by a second-order differential equation which is integrated in order to obtain droplet position information. Stokes' viscous drag on the droplet's translational motion is incorporated. Due to the reliance on the use of standing waves, any fluctuations in the resonance frequency are monitored and evaluated. The slow temperature increase in the DPM will change the resonance frequency of the chamber (temperature detuning) and is also taken into account. The resonance frequency is also affected by the existence of the inclusion and by its position within the chamber (volumetric detuning.) The simulation includes an analytic expression which describes this phenomenon. Since the DPM is designed for use in the microgravity environment of an orbiting space shuttle, calculations are also adjusted to account for behavior specific to the shuttle motion. [Work supported by Jet Propulsion Laboratory, Contract No. 958722.]