The current research projects in the UW Fluid Flow Physics group span a diverse range of topics relevant to fluid mechanics, from modeling flow in a curved tube to harvesting energy from small scale fluid structures. Each research project is explained briefly below. For further information, please contact Prof. Peterson (peterson &at& mme &dot& uwaterloo &dot& ca).

Flow in curved tubes, both steady and unsteady, has long captivated fluid mechanicians due to the rich flow physics and practical applications. This research program is at the interface of traditional fluid mechanics and the blossoming field of biofluid mechanics. The human vasculature is tortuous, consisting of virtually no straight sections of any considerable length. Thus, examining curved tubes as an arterial model offers a welcome physiological relevance. In this study we examine the role of stent struts, that is, implanted mechanical devices for reopening an occluded vessel, on the axial and secondary fluid flow development. This problem is tackled from an analytical perspective, modeling the stent as a small perturbation to a nominally circular cross-sectional geometry, as well as experimentally and numerically when the flow parameters and geometry are such that the analytical problem is intractable. This fundamental flow study has implications beyond the vasculature, such as heat transfer and mixing.

*In collaboration with Dr. Maurizio Porfiri
at the
Polytechnic Institute of New York University.*

Ionic polymer-metal composite (IPMC) actuators have shown promise as miniature underwater propulsors due to their high flexibility, reduced weight, and low activation voltage and power consumption. This research project focuses on analyzing the hydrodynamics of a vibrating IPMC actuator in an aqueous environment in order to develop a comprehensive understanding of thrust generation mechanisms for application to underwater propulsion. The analysis employs experimental methods, such as time-resolved Particle Image Velocimetry to visualize and quantitatively measure the flow field, and numerical models to probe into the dominant underlying physical mechanisms. The ultimate goal is to provide a set of design criteria that can be used in underwater robot development.

*In collaboration with Dr. Maurizio Porfiri
at the
Polytechnic Institute of New York University.*

Recent advances in lightweight smart materials have opened the door to scientific and technological advancement in the area of energy harvesting for limited power consumption devices. This research program addresses the grand challenge of extracting usable energy from small-scale aquatic environments. More specifically, this program seeks to exploit coherent fluid flow structures for energy harvesting. Coherent fluid structures, such as Karman vortex streets and turbulent eddies, are generally present in aquatic environments and are due to a variety of mechanisms, including flow separation from fixed immersed bodies, thermal and pressure gradients, and momentum transfer from swimming animals. Practicality dictates that harvesting devices for underwater applications be lightweight, require small forces and low frequencies to elicit motion and thus energy harvesting, produce sufficient electrical power to run a set of microdevices, and operate in wet conditions. Ionic Polymer Metal Composites (IPMCs) meet all of these requirements and are thus the primary focus of this program.

*In collaboration with Dr. Byron Erath at
Clarkson University.*

Existing models for the pressure distribution along the walls of the vocal folds utilize Bernoulli's equation in the diverging vocal fold passage, and thus relate the pressure to the velocity in the section. Unfortunately, Bernoulli's equation is known to give erronious results in diffusers due to the strong influence of boundary layer growth and separation on the velocity field. Furthermore, the nature of the vocal fold geometry leads to asymmetry in the flow field downstream of the minimal glottal area due to a Coanda type effect. Present models do not account for this asymmetry and the resulting asymmetric loading on the vocal folds. This project seeks to develop a semi-empirical model for the pressure distribution along the vocal fold walls by using boundary layer methods to predict the velocity profiles in the attached wall jet and thus estimate the pressure distribution. The novel Boundary Layer Estimation of Asymmetric Pressure (BLEAP) method can be incorporated into two-mass vocal fold models to predict the self-oscillatory behavior.