Velocities of water drops falling in oil media and the wake effect

Abstract

Laboratory experiments were conducted on the velocities of pairs of equal-sized water drops of 3.3 mm diameter, falling with an initial vertical separation in undisturbed oil media (in presence and in absence of an electric field in mustard oil, and in absence of a field in kerosene oil). During the fall from the initial point, the position where a drop attained terminal velocity while falling alone, the following (upper) drop got accelerated with respect to the preceding (lower) drop due to the wake effect. The wake effect in mustard oil existed up to

<span style="font-size:14.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";color:black;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">an initial vertical separation of 2 cm and 2.4 cm for a pair of drops, respectively, in absence and in presence of an electric field of 230 V cm^-1 for their collision at the end of the 86-cm fall. The wake effect in kerosene oil existed up to an initial vertical separation of 4.5 cm in absence of a field for collision of a pair of drops at the end of a 72-cm fall.</span>