Unsteady wall effects on hydrodynamics and energy absorption in a flexible traveling wave plate: Roles of dimensionless wall distance and wave speed

This study investigates the hydrodynamic and energy absorption characteristics of a two-dimensional flexible traveling wave plate in energy absorption mode, focusing on the impact of unsteady wall effects and their interaction with the wake vortex structure. Numerical simulations reveal that the wall effect significantly alters both the time-averaged and instantaneous force coefficients, with variations depending on the dimensionless wave speed(C) and wall distance(D). Specifically, the time-averaged transverse force coefficient decreases by 45.9 % at D = 0.2 and C = 0.4 compared to unbounded conditions, while the longitudinal force coefficient exhibits a complex trend, transitioning from a monotonic decrease to a decrease followed by an increase, influenced by wave speed. The wall effect also disrupts the symmetry of the instantaneous force coefficients, complicating the force curves. Furthermore, the wall increases the average differential pressure power, slightly enhancing energy absorption efficiency at D = 0.8–1.0, but reducing efficiency at D = 0.2–0.7. The wall also disturbs the wake vortex structure, causing premature dissipation of the positive vortex core and weakening energy harvesting near the wall. These findings highlight the wall's complex influence on hydrodynamic performance and energy absorption, offering insights for energy-harvesting device design near the wall.