Nonlinear dynamic responses of a flexible plate submerged in a tandem square cylinder wake

Understanding the interaction between fluid flow and flexible structures remains a critical area of research, particularly in engineering applications involving flow-induced vibration control, energy harvesting, and structural stability. In this study, the author examines the fluid–structure interaction behavior in a tandem arrangement comprising two identical square cylinders and a downstream flexible plate, with a fixed gap ratio (GR = L/D = 4.0) separating each component. The central aim is to evaluate how wake-induced forces influence the dynamic response and nonlinear vibration characteristics of the plate across a range of Reynolds numbers (50 ≤ Re ≤ 200). A series of transient numerical simulations were carried out in ANSYS Fluent, using a refined mesh and time step selection that satisfies stability condition. The analysis highlights a complex interplay between vortex shedding and structural motion, where both the Strouhal number and hydrodynamic force distribution are sensitive to changes in Re. Importantly, the plate exhibits a nonlinear oscillatory behavior in the transverse direction, which is accurately characterized by a third-order polynomial function in terms of Re. These findings offer meaningful contributions to the understanding of wake–structure interaction and may inform future design strategies for systems utilizing flexible components in fluid environments.