This paper presents a numerical study on the self-induced flapping dynamics of an inverted flexible foil in the context of energy harvesting using piezoelectric elements. The inverted foil considered in this study is clamped at the trailing edge and the leading edge is free to oscillate. To simulate the nonlinear flapping dynamics of an inverted flexible foil, a high-order coupled fluid-structure solver based on the combined field with explicit interface (CFEI) has been developed. Additionally, a simplified piezoelectric model has been presented to determine the electric energy that can be harvested through flapping. The coupled solver is validated over a flexible foil fixed at the leading edge and trailing edge free to oscillate. A systematic study on the flapping response of an inverted flexible foil has been performed for a wide range of non-dimensional bending rigidity for a fixed Reynolds number of 1000 and mass ratio of 0.1. As a function of decreasing bending rigidity, four flapping regimes have been observed: (i) fixed-point stable, (ii) inverted limit-cycle oscillations, (iii) deformed flapping and (iv) flipped flapping. The inverted limit-cycle oscillations are characterized by low-frequency large amplitude oscillations which generate O(103) times greater strain energy than a flexible foil fixed at the leading edge, which has a profound impact on the development of ocean current based energy harvesting devices.

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