Expanding the temperature range for generation of droplet clusters over the locally heated water surface

Abstract

A wide range of possible temperatures of levitating water droplets is interesting for the upcoming laboratory studies of biochemical processes in the droplets. The previously obtained temperature of droplets levitating above the locally heated water of room temperature appeared to be too high for some important biochemical experiments. At the same time, it was not obvious that one can generate much colder droplets. Fortunately, this problem is solved experimentally in the present study with the use of a strong cooling water layer and ambient air. The modified experimental configuration which includes a separate volume of cold air just above the central part of water layer is designed to work at quite different temperature conditions. It is shown that even moderate local heating of water surface is the most important factor to produce sufficiently large self-assembled levitating clusters of water droplets which are similar to those observed at normal temperature conditions. The effect of ambient temperature on both the generation process and characteristics of droplet clusters is studied in the paper.