Speaker & Title:
Dr Matthew Moore (Mathematical Institute, Oxford University): Moving beyond Wagner: applying classical impact theory to droplet impact problems
Abstract:
Impact problems have a wide range of applications throughout real-world phenomena and industrial processes ranging from ship-slamming to inkjet printing and coating processes. With recent advances in camera technology, visualisation techniques and high-powered computing, we are increasingly able to see more of the phenomena occurring at small length- and timescales in droplet impacts. Understanding these phenomena can be vital in both promoting and inhibiting splashing.
In this talk, we will discuss the role that classical Wagner theory, developed for applications to naval architecture in ship-slamming, can play in the much smaller scale problem of droplet impact. Wagner theory was developed to help predict pressure profiles on the hulls of ships and sea-planes, so much of the finer detail of the splash itself was ignored. However, it is this very splash that is of importance in many droplet impact scenarios. Since impact problems are highly nonlinear and complex, it is desirable to use modelling to help predict certain properties, such as the location of the root of the splash jet (or ejecta), enabling us to focus our numerical or experimental investigations on a subset of the full impact problem. Therefore, we will develop a droplet Wagner model and compare the predictions to direct numerical simulations in Gerris, highlighting what the theory does well and where it is lacking. In the latter cases, we will discuss possible extensions to the theory to improve the predictions.