RESEARCH QUESTIONS
  1. How can the components of the piezoelectric harvester structure, energy conditioning circuit, and energy storage system be modified in order to maximize the magnitude of energy stored?
  2. How closely will the theoretical energy harvesting capability of the integrated product compare to the experimentally determined energy harvesting capabilities?
PROJECT

What are Vortex Induced Vibrations (VIV)?

Vortex induced vibrations occur when a bluff body, a non streamlined object, rests in a flow. The flow splits apart so that the layers closest to the body start curving around behind it (Billah & Scanlan, 1991). These layers, known as free sheer layers, turn in opposite directions around the body (Billah & Scanlan, 1991). It is thought that these layers alternate in feeding a vortex until the vortex’s rotation pulls the opposite sheer layer across the object, thereby shedding the vortex and commencing the creation of the next vortex (Gerrard, 1966). The end result is that vortices are created on alternating sides of the bluff body with a repeating frequency (Henri, 1908). The formation and shedding of a vortex causes the bluff body to experience unequal pressures from different sides, leading the body to move back and forth perpendicular to the flow. This oscillating motion is greatest when the shedding frequency is equal to the natural oscillating frequency of the object (Billah & Scanlan, 1991). These vibrations can be harvested by various means, including through the usage of piezoelectric materials and conventional mechanical generators (Bernitsas, 2010; Taylor, Burns, Kammann, Powers, & Welsh, 2001).