## 1 Introduction
The shape alteration aimed to influence aerodynamic characteristics for the purpose of suppressing vortex-induced vibrations. Depending on the applied metasurfacepattern, the system's vortex-induced vibrations could either be enhanced or suppressed compared to a smooth cylinder. Research in [29] demonstrated that for effective VIV energy harvesting, the orientation of the bluff body should align with the beam at low wind speeds (below 2 m/s) and be perpendicular to it at high speeds (above 2 m/s). A piezoelectric energy harvesting system utilizing vortex-induced vibrations can take the form of a wind turbine, a blower that increases airflow in a tunnel, a vortex-inducing obstacle, and a circular piezoelectric converter [30]. At low wind speeds, it is possible to use an auxetic nonlinear system for harvesting energy from vortex-induced vibrations [31]. The authors of [32] propose using magnets in conjunction with piezoelectric materials that generate current under vibration. The addition of magnets introduces nonlinearity, enabling the device to operate more effectively across a broader range of vibration frequencies. A specialized element called a coupler is placed inside the pipe, while piezoelectric energy harvesting elements are positioned outside the pipe. When designing a VIV-enhanced energy harvesting device for pipeline flow, it is crucial to consider the appropriate bluff body cross-sectional shape and the natural frequency range [33]. The impact of using hybrid bluff bodies with variable cross-sections on the efficiency of energy harvesting from vortex-induced vibrations was investigated in [34]. Adding a specific type of \"nonlinear stiffness\" to VIV-based wind energy harvesters can significantly improve their performance and make them more effective across a wider range of wind conditions [35]. Placing a fixed square plate behind a cylinder has a significant impact on its vortex-induced vibrations. Numerical studies have shown that by varying the plate's height and the distance between the plate and the cylinder, the intensity of the cylinder's vibrations can either be increased or decreased [36]. A mathematical model of a piezoelectric cantilever beam with a tip mass subjected to vortex-induced vibrations was presented in [37]. The harvested energy under deterministic harmonic excitation was estimated as a function of a dimensionless velocity parameter. The analysis showed that lower damping leads to greater harvested energy, with peak power occurring near a dimensionless frequency of 1. A tri-stable vibro-impact wind energy harvester utilizing vortex-induced vibrations exhibits unique dynamic properties and potentially superior energy harvesting performance compared to traditional mono- and bistable harvesters [38]. Recent studies by [PERSON] [39] investigated the flow around cylindrical bluff bodies using trailing-edge splitter plates, attached fins, biomimetic surfaces, and oscillatory morphing surfaces. The research gap addressed in this work concerns the influence of mass and velocity on the voltage generation capability of a harvester with a cylindrical bluff body mounted transversely to the axis of a cantilever beam with a piezoelectric element. While other authors have analyzed various bluff body geometries, the influence of geometric and mass parameters has not been examined in the manner presented in this study. This paper continues the authors' previous research on energy harvesting but specifically focuses on how the aforementioned parameters affect system performance. Additionally, the 0-1 test was applied as a complementary method for analyzing the system's dynamics, particularly to distinguish between oscillatory behavior and cases where the system becomes trapped in a potential well. The analysis above indicates the high potential of oscillating bluff bodies cooperating with piezoelectric elements for harvesting energy from airflow. Earlier studies focused on a hybrid-geometry bluff body in the form of a cylinder with a varying cross-section [40].