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

1512192(Kanso) & 1509071（Sotiropoulos）拟议研究的目标是通过实验和数值研究不规则形状物体穿过流体-空气界面时的运动，以及由于物体的存在而在界面和大部分流体中发生的现象。了解潜在的现象可以通过控制物体形状或控制流体类型来控制过程。这项研究的结果可能会对小型机器人车辆的设计产生影响，这些车辆可以通过流体-空气界面移动，也可以用于海上风力涡轮机或石油平台的设计。物体进入的问题通常是复杂的，即使是对于规则形状的物体，如球体和圆盘，但对于具有尖锐的主要几何形状的物体，如圆锥或金字塔形状的物体，特别有趣，在这些物体中，物体几何形状和在流体-空气界面及其附近形成的复杂的涡流之间的相互作用可以帮助消散来自穿过流体边界的物体的冲击能量。本提案将分析在多相不可压缩流体中运动的物体的流-结构相互作用，并将特别探索如何利用物体的几何形状和材料特性与流体界面处和附近发展的复杂流动结构（波和漩涡）之间的相互作用来阻碍或促进固体物体的运动。在本项目中，将使用精心设计的实验以及数学和计算模型来研究以下两个问题：(i)正演问题：对于给定的多相流体介质和物体的形状/材料特性，物体及其周围流体的正演动力学是什么？（ii）反问题：两种类型的问题：a.对于期望的响应，例如在给定的流体环境中帮助固体物体运动，物体应该满足哪些几何/材料设计原则？b.对于期望的响应，如阻碍固体物体的运动，流体介质应具有什么性质？活动还包括南加州大学和明尼苏达大学的本科课程开发，以及通过南加州大学的VAST项目和圣佩德罗的Cabrillo水族馆向大洛杉矶地区的K-12学生推广。

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.