Experimental investigation of energy harvesting eel in the wake of bluff body under ocean waves

Abstract

Investigation of the energy harvesting from deep water waves by using flexible piezoelectric eel in a controlled environment is studied. Energy harvesting potential is examined as a function of streamwise distance from the fixed cylinder and spanwise gap along with the cylinder at different wave conditions. Output voltage and eel flapping behavior are dependent on cylinder vortices caused by local wavelength and wave amplitude. Maximum energy is harvested when the eel is placed near to the surface caused by high flapping amplitude and frequency. Similarly, at greater depth low flapping amplitude is observed resulting in small output voltage. Maximum output voltages are found at the shorter wavelength and at a streamwise distance of gx = 1.25 (where gx is the ratio of spacing “S” between cylinder and eel to the diameter of cylinder “D”) for all spanwise gaps along with the cylinder and minimum voltages are calculated at a longer wavelength and streamwise distance gx = 0.75. An increase of 65% in energy harvesting is observed by switching longer wavelengths (λ) to a shorter one and changing the piezo-eel spanwise gap from deep to the shallow depth. Whereas, an increase of 31.5% was found by keeping wavelength constant and changing the spanwise gap of eel. Furthermore, it is observed that energy harvesting from the wake of a bluff body in the wavy motion of water is sensitive to the wavelength and wave height.