Flow field interference effect on energy harvesting enhancement of a combined fluid-structure interaction system in channel flow

In this paper, the flow field between two vibrating systems and the potential to increase the harvested energy by the interference of flow fields was numerically evaluated. A combined configuration of a cylinder-splitter hyperelastic plate placed at the wake of a vortex-induced oscillating cylinder was studied in a laminar channel flow at a Reynolds number of 200. A finite-volume method was adopted for solving the flow field over polyhedral cells. Overset grid and mesh morpher algorithms were employed to handle different mesh motions. On the other hand, a finite element method was exploited to solve the structural displacement of the hyperelastic plate. Having validated two individual similar systems, the effects of different spacing values and the reduced frequency of the vibrating cylinder on the amount of harvested energy were investigated in the combined configuration. According to results, no flow unsteadiness took place for the small spacing values at low reduced velocity. Increasing the natural frequency, the oscillation of the vibrating cylinder excited its boundary layer, causing it to separate. Moreover, the presence of such oscillations at downstream of the vibrating cylinder altered its response yielding higher energy production. Results showed that at some specific reduced velocities of the oscillating cylinder, the vortex shedding phenomenon did not occur if the spacing between the cylinders was small. However in other cases, the relative power efficiency of the oscillating cylinder in the combined system was increased from 29 % to more than five times of the isolated oscillating cylinder depending on the parameters.