UPtoPARIS

ESPCI proposes a brand new international doctoral programme – UPtoPARIS: More info here: https://www.upto.paris/-upTo-paris-.html

The first call closes on February 28th, 2018. Our project on bio-inspired wave-energy conversion is one of the projects selected (project page here).

Bio-inspired elastic structures for ocean wave energy conversion

The purpose of this project is to study a surface wave absorbing system with potential for both coastal erosion control and renewable energy production. The system is inspired by the fluid flow calming effects of aquatic vegetation in near-shore and riverine environments. The system consists of an ensemble of flexible slender structures mimicking an underwater canopy whose collective dynamics is forced by the action of the waves. The reconfiguration of slender structures by their interaction with an external flow has been a vibrant subject of research in the past decade, and applications abound in this archetype of interdisciplinary subject where biology, physics and engineering meet.
Those problems stem from purely biological questions such as the mechanics of plants in the wind or underwater vegetation, to bio-inspired engineering solutions for problems as diverse as mooring and riser systems or eolian energy conversion. But very few studies have focused on such flexible systems for wave energy conversion.

The core of the present project is the mechanical energy conversion inherent to the deformation of a flexible structure: as a deformable structure bends under the action of an external flow, it converts part of the kinetic energy of the surrounding fluid into elastic energy. From an erosion control point of view, the energy absorbed by such an elastic mechanism is thus removed from the energy available in a given flow field to erode the littoral, even if it is given back to the fluid through disordered smaller scale vortical motions during the subsequent relaxation of the elastic structure. An ongoing study at the PMMH laboratory at ESPCI Paris has focused on the dynamics of such fluid-structure interaction mechanisms, in particular studying the effect of the canopy geometrical parameters on the surface wave attenuation properties.

We propose in the present PhD project to examine the possible methods for harvesting part of this energy, which would otherwise be dissipated. Candidates at the laboratory scale are piezo-electric systems that we currently testing, but the goal of the proposed project is to examine other technologies such as electroactive polymer membranes that can be scaled up to a realistic application. Coupling energy harvesting to the dissipation of incoming ocean wave energy within a single mechanical system inspired from a field of rooted aquatic vegetation is the keystone of the present proposal.