Analysis of surface oscillation of droplet under microgravity for the determination of its surface tension

Abstract Shape changes in a levitated droplet can affect the surface oscillations and hence the apparent surface tension of the droplet. The effect of those changes was investigated using the electromagnetic levitation method under microgravity. Microgravity conditions were obtained using the drop-shaft at the Japan Microgravity Center (JAMIC). The results established that the surface oscillation of a droplet is much simpler under the 10 −5 G condition than under 1 G. The droplet shape was controlled by changing the current ratio between the quadrupole coil and the dipole coil. When the droplet shape is (a) spherical only one peak is observed, (b) is close to a sphere, but slightly distorted, five peaks are observed and (c) the droplet is significantly distorted, a particular oscillation mode is usually excited and only one peak is sometimes observed. However, for the third condition, the surface tension values derived from the frequency of the single peak are erroneous.