Non-expert summaryThis is an experimental study of removal of dust particles from a hydrophobic surface by a rolling/sliding water droplet. The effect of surface inclination angle on droplet dynamics and dust removal is analyses and compared with a model. Droplet rolling dominates over sliding. Removal is mainly due to the droplet liquid coating the particles as it passes over the particle, and the removal efficiency is determined by the inclination of the surface.
Non-expert summaryThis is a review of heat transfer and flow phenomena during unsubmerged liquid jet impingement on solid surfaces, such as when a water jet passes through air and impinges on a wall. Both axisymmetric and planar jets are considered. The focus is on convective transport without phase change. Results for the stagnation zone are given first, followed by those for the regions downstream. Correlations are presented for flow and heat transfer phenomena. The heat fluxes that can be generated in these systems can be large, so there is a considerable body of work on topic. Splattering - the formation of breakaway droplets from the liquid film - that accompanies turbulent jet impingement is described. Other aspects of liquid jet impingement cooling are discussed briefly.