UNS: Collaborative Research: Crossing the boundary: motion of solid objects across air-liquid interfaces

1512192(Kanso) & 1509071(Sotiropoulos)

The goal of the proposed research is to investigate, experimentally and numerically, the motion of irregularly shaped objects as they cross fluid-air interfaces and the phenomena that occur at the interface and the bulk of the fluid because of the presence of the object. Understanding the underlying phenomena could lead to controlling the process by controlling the object shape or controlling the type of fluid. Results from this research can have implications for the design of small robotic vehicles that move across fluid-air interfaces or the design of off-shore wind turbines or oil platforms.

This problem of object entry is generally complex, even for regularly shaped objects, such as spheres and discs, but is particularly interesting for objects with sharp leading geometries, such as cone- or pyramid-shaped objects, where the interplay between the body geometry and the complex vortical flows that develop at and near the fluid-air interface could help to dissipate the impact energy away from the body crossing the fluids' boundary. This proposal will analyze the fluid-structure interactions of objects moving in and across multi-phase incompressible fluids, and will particularly explore how the interplay between the object's geometry and material properties and the complex flow structures (waves and vortices) that develop at and near the fluid interfaces can be exploited to hinder or facilitate the motion of the solid object. During this project, carefully designed experiments as well as through mathematical and computational models will be used to investigate the following two problems: (i) Forward problem: for a given multi-phase fluid medium and shape/material properties of the object, what is the forward dynamics of the body and the surrounding fluids? (ii) Inverse problem: two types of problems: a. For a desired response such as aiding the motion of the solid object in a given fluid environment, what geometric/materials design principles should the object fulfill? b. For a desired response such as hindering the motion of the solid object, what properties should the fluid medium have? Activities are also proposed that involve undergraduate curriculum development at USC and at the University of Minnesota, as well as outreach efforts to K-12 students in the greater LA area through the USC VAST program and the Cabrillo Aquarium in San Pedro.