Water Droplet Impact And Spreading On A Narrow Gap

The impact and spreading of a water droplet on a gap between two parallel plates has been studied experimentally. A deionized water droplet (2.03 mm diameter) impacted the plates at velocities of 0.06, 0.5, 1.0, and 1.5 m/s; the tested gap spacings of the parallel glass plates were 50, 100, and 150 μm. Using a high-speed camera, we simultaneously photographed the drop spreading both above and within the gap. We show that water begins to penetrate the gap immediately after impact. On the largest spacing tested, up to 10% of the initial drop volume can penetrate the gap before the maximum spreading diameter is reached.