Experimental Study on the Energy Budget in a Drop Impact

Abstract

Prediction of maximum spreading diameters of impacting drops is crucial for determining the quality and efficiency of many industrial applications using drop-on-demand or spray technology. In order to construct an exact theoretical model for predicting the maximum diameter, one needs to determine a time constant being required for the radial pressure gradient in a spreading drop to be disappeared, which is difficult to derive theoretically. We experimentally obtained the time constant by focusing on the energy budget during drop impact, especially on the viscous dissipation. By considering the time delay, we developed a theoretical model for predicting the maximum spreading diameters. The model shows good agreement with experimental results, revealing the importance of the internal velocity field in a drop.