IMPACT OF COMPOUND DROPS ON A PLANE SOLID: ROLE OF THE CORE DIAMETER

The impact of water-in-Jatropha biodiesel compound drops on a solid surface is examined. The effects of variation of the core drop diameter (or the volume fraction, cc) and the impact velocity (or Weber number, We) of the compound drops on the outcomes of the impact are reported. With an increase in cc, there is a change in the interaction of inertia, viscous and surface forces resulting in interesting changes in the impact dynamics. The maximum spreading factor (pmax), the average spreading rate, and the receding are observed to depend on the volume fraction. pmax increases with the rise in cc due to reduced viscous dissipation in the drop. The low volume fraction compound drops do not show any significant receding after pmax. However, significant receding is observed at higher cc as water has very high surface tension. The water core recedes over the Jatropha biodiesel shell film deposited on the solid, resulting in double lamella formation. The compound drops of very high cc show breakup of the core drop during receding at high We, resulting in deposition of small secondary core droplets on the shell film. The normal average spreading rate first decreases with the rise in cc and then increases again when cc rises to very high values.

Automated summary

The impact dynamics of water-in-Jatropha biodiesel compound drops on a solid surface change interestingly with the increase in volume fraction, including the increase in spreading factor and the appearance of receding.