en Offshore Structure مقاله پژوهشي Research Paper The horizontal kinetic energy of the fluid flow, from on-land wind to ocean tidal stream, is one of the most promising sources of the energy. In the field of renewable energies, power extraction from Flow Induced Vibration (FIV) of bluff bodies is a fast growing research area which has seen a great advancement over the last decade. In this study, the FIV energy harvesting potential of a sharp edge square cylinder in two different flow incidences is investigated. The square cylinder, depending on its orientation with respect to the incident flow, demonstrates VIV or galloping types of responses. The results indicate that the square cylinder with a flat side perpendicular to the flow has a galloping type of response. In contrast, the same cylinder with a sharp vertex pointing the flow (diamond configuration) shows a VIV type of response. The hydroelastic efficiency of the resonating square cylinder is significantly higher than that with the galloping type of response. This shows the great advantages of diamond VIV excavators over square galloping harvesters. FIV energy harvesting, Hydroelastic efficiency, VIV, Galloping, Square and diamond cylinders. 1 8 http://ijmt.ir/browse.php?a_code=A-10-391-2&slc_lang=en&sid=1 Vahid Tamimi vahid.tamimi@ut.ac.ir 10031947532846003629 10031947532846003629 Yes School of Civil Engineering, College of Engineering, University of Tehran Mohammad Said Seif seif@sharif.edu 10031947532846003630 10031947532846003630 No Department of Mechanical Engineering, Sharif University of Technology Selda Shahvaghar-Asl shahveghar@yahoo.com 10031947532846003631 10031947532846003631 No Department of Civil Engineering, Sharif University of Technology Seyed Taghi Omid Naeeni stnaeeni@ut.ac.ir 10031947532846003632 10031947532846003632 No School of Civil Engineering, College of Engineering, University of Tehran Mostafa Zeinoddini zeinoddini@kntu.ac.ir 10031947532846003633 10031947532846003633 No Department of Civil Engineering, K.N.Toosi University of Technology