Department of Mechanical Engineering

Modeling the Unsteady Flows of Biological and Bio-Inspired Systems

Keith Moored, Postdoctoral Research Associate, Department of Mechanical and Aerospace Engineering,Princeton University

Hopeman 224

The use of autonomous underwater and aerial vehicles in law enforcement, marine surveying and military operations has seen enormous growth in the past ten years. However, the full potential of these devices has not yet been realized.  Bio-inspired systems may offer the next-generation solutions that are fast, efficient, maneuverable, stealthy and have a broad operational range producing a multi-functional platform.  There are two particular features of swimming and flying organisms that are of interest: (1) unsteady locomotion and (2) flexible appendages.  This talk will discuss efforts to develop simple but realistic models for unsteady locomotion with flexible propulsors.  

First, I will discuss the development of an advanced panel method with viscous corrections to study the physics of unsteady locomotion.  As a biological focal point for the modeling, the performance and flow structure produced by batoid rays is examined, revealing how thrust and efficiency are connected to the structure of the wake.  To further simplify the physics of batoid ray swimming, a free-swimming two-dimensional pitching panel is investigated with the panel method to reveal scaling laws of unsteady locomotion.  Second, the physical mechanisms that lead to efficient propulsion in unsteady flow systems are investigated using the concept of wake resonance theory.  The theory is shown to agree with experiments on a three-dimensional rigid bio-inspired propulsor and two-dimensional flexible pitching panels.  Furthermore, the theoretical framework identifies a coupled resonance phenomena that leads to high efficiency for flexible propulsors.