Piezoelectric energy harvesting from vortex-induced vibrations of circular cylinder A. Mehmood a , A. Abdelkefi a , M.R. Hajj a,n , A.H. Nayfeh a , I. Akhtar b , A.O. Nuhait c a Department of Engineering Science and Mechanics, MC 0219, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA b Department of Mechanical Engineering, NUST College of Electrical & Mechanical Engineering, National University of Sciences & Technology, Islamabad, Pakistan c Department of Mechanical Engineering, King Saud University, Riyadh 11421, Saudi Arabia article info Article history: Received 10 September 2012 Received in revised form 16 March 2013 Accepted 19 March 2013 Handling Editor: M.P. Cartmell Available online 7 May 2013 abstract The concept of harvesting energy from a circular cylinder undergoing vortex-induced vibrations is investigated. The energy is harvested by attaching a piezoelectric transducer to the transverse degree of freedom. Numerical simulations are performed for Reynolds numbers (Re) in the range 96≤Re≤118, which covers the pre-synchronization, synchro- nization, and post-synchronization regimes. Load resistances (R) in the range 500 Ω≤ R≤5MΩ are considered. The results show that the load resistance has a significant effect on the oscillation amplitude, lift coefficient, voltage output, and harvested power. The results also show that the synchronization region widens when the load resistance increases. It is also found that there is an optimum value of the load resistance for which the harvested power is maximum. This optimum value does not correspond to the case of largest oscillations, which points to the need for a coupled analysis as performed here. & 2013 Elsevier Ltd. All rights reserved. 1. Introduction Converting ambient and aeroelastic vibrations to a usable form of electric power has been proposed for powering electronic components, such as microelectromechanical systems, actuators [1,2], and health monitoring wireless sensors [3–5], or for replacing small batteries that have a finite life span or would require hard and expensive maintenance [6,7]. Different transduction mechanisms can be employed for converting these vibrations to electric power, including electrostatic [8,9], electromagnetic [10], and piezoelectric [10,11] transduction. Of particular interest is the piezoelectric option, which has received the most attention because it can be used to harvest energy over a wide range of frequencies [9] and can be easily implemented. To date, most of energy harvesting from mechanical vibrations has concentrated on exploiting base excitations [12–16]. More recently, there has been several investigations into the conversion of aeroelastic vibrations into electric power [17–26]. The flow past a vibrating cylinder is a canonical problem that has been investigated to understand various flow physics phenomena. When a fluid passes over a cylinder, an organized and periodic array of concentrated vorticity, known as the von Kármán vortex street, appears in the wake. For stationary cylinders, the vortex-shedding frequency f vs is usually expressed as a nondimensional frequency, called the Strouhal number St ¼ f vs D=U ∞ , where U ∞ and D are, respectively, the Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/jsvi Journal of Sound and Vibration 0022-460X/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jsv.2013.03.033 n Corresponding author. Tel.: +1 5402314190; fax: +1 5402314574. E-mail address: mhajj@vt.edu (M.R. Hajj). Journal of Sound and Vibration 332 (2013) 4656–4667