Temperature effects on transient behaviour of a free-falling liquid gallium drop

The present investigation presents the results of an experimental study of a free-falling liquid gallium drop in a quiescent water. Experiments were performed with different drops size in the range of 2.67 mm to 5.56 mm. All experiments were carried out under isothermal conditions, where the liquid Gallium temperature equals the temperature of the quiescent water inside the column. The temperature of both phases was investigated in the range of 30 degrees C to 70 degrees C. The study focuses on the transient behaviour of the falling drops and their aspect ratio as well as the effect of size, viscosity ratio and temperature. The captured high speed images are studied to quantify the evolution of the aspect ratio of the falling Gallium drops in time. Transient oscillations of the aspect ratio are found to exhibit a decaying trend in time. Amplitude and frequency of these oscillation were analysed. The frequency of aspect ratio oscillations were found to decrease with Eotvos number following the f D-3/2 law according to Rayleigh theory The free fall velocity of the Gallium drop is found to be highly correlated to the aspect ratio oscillations. Furthermore, whilst the oscillations amplitude was found to be sensitive to viscosity ratio, the frequency of oscillations was not affected in any noticeable way. The trends reported are limited to the range of experimental conditions investigated in this study.