A02

A02: Experimental Investigation of Coalescence and Breakup of Droplets on Solid Surfaces – Generic Configuration Sessile Drop

Above: Generic configuration Sessile Drop. Below: Influence of the Spreading Coeffincient on the coalescence of drops. A contact angle forms (A) when the Spreading Coefficient ist negative. At a positive Spreading Coefficient a film of one droplet spreads over the other (B). C shows two immiscible drops 150 ms after coalescing. Image: SFB 1194
Above: Generic configuration Sessile Drop. Below: Influence of the Spreading Coeffincient on the coalescence of drops. A contact angle forms (A) when the Spreading Coefficient ist negative. At a positive Spreading Coefficient a film of one droplet spreads over the other (B). C shows two immiscible drops 150 ms after coalescing. Image: SFB 1194

This experiment is designed to examine the coalescence of drops on a surface with a contact angle less than 90°. Furthermore, the breakup of evaporating drops on a complex surface will be studied. In both cases the central goal is a better understanding of these processes. Special attention will be directed to capturing the velocity field in the drop directly at the contact line. Special optical arrangements will allow a spatial resolution down to a few micrometers. The surface is constructed to also allow temperature gradients and electrical fields to be imparted. Temperature measurements will be performed using an infrared camera.

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