Amplitude modulation of an elastic plate by tuning upstream wakes in cross-flow

The flow-induced vibration of an elastic plate has been studied in different configurations such as the conventional, inverted and vertical mounted to a wall. Recently, a cross-flow configuration was proposed by Pandey et al. (J. Fluids and Structures 122 (2023): 103977), where a vertical elastic plate cantilevered at its bottom is kept in an open domain, allowing flow from both top and bottom. It resulted in reduced loss of flow energy with ordered oscillations due to the absence of a wall, hence a promising energy harvester. We extend these findings to enhance the amplitude by introducing an additional plate upstream and investigate the effects of proximity and wakes on the coupled dynamic response of both plates. We vary the elasticity of the upstream plate while keeping it constant for the downstream plate. 2D simulations are performed using an in-house sharp-interface immersed boundary method-based fluid-structure interaction solver at a Reynolds number of 100. The upstream plate shows similar characteristics to an isolated plate for larger gap ratios, whereas the vibrations are suppressed for small gap ratios. A significant increase in amplitude and the broadening of the lock-in regime of the upstream plate is observed. Wakes of the upstream plate are seen to profoundly affect the response of the downstream plate where a sudden rise in its amplitude is noted after a certain reduced velocity depending upon the gap ratio.