## 1 Introduction
[35] examined the effect of a splitter plate placed in the near wake of a circular cylinder on the performance of a piezoelectric WEH. The results showed that the harvester was able to maintain significant amplitude vibrations, even beyond the lock-in wind speed range, and, hence, the range of effective working wind speed was expanded. [PERSON] et al. [36] augmented the rear face of the square prism with Y-shaped fins of different lengths and fork angles. This modification reduced the rise time of the harvester by as much as 75% compared to the finless square prism. The above aerodynamic shapes were optimized based on the typical cross-section. The bluff bodies were constructed according to research experience and galloping characteristics. A circular arc bluff body has been studied for applications such as a velocity threshold detector and passive stability control of an unmanned flying vehicle. A circular arc bluff body is also capable of producing galloping oscillation. [PERSON] [37] reported and analyzed experimental results on the forces generated by a high-chamber thin section with a curved plate, and made measurements of the flow field using particle image velocimetry. Variations of lift were related to changes in the topology of the flow field around the section. These results explained the flow around a high-chamber thin section and provided a detailed benchmark database in a simple geometry for model validations. [PERSON] et al. [38] tested arc bodies with different sections and analyzed the force crisis. [PERSON] et al. [39] tested three geometrically similar circular arcs over a range of Reynolds numbers, from 53,530 to 218,000. The force crisis and boundary layer were analyzed by force measurement and particle image velocimetry, similarly to the circular cylinder. [PERSON] et al. [40] investigated a curved arc bluff body WEH experimentally and theoretically. Based on the particle image velocimetry, the separation flow attached to the rear surface of the blade at the initial position, and then the flow pattern enhanced the galloping performance. A circular arc bluff body is a blade-shaped bluff body with great energy harvesting performance. WEHs with a blade-shaped bluff body can achieve a much higher energy output than those with a square prism. [PERSON] et al. [41] proposed and designed a three-blade bluff body for wind energy harvesting. Both numerical simulations and experimentsconfirmed that the three-blade structure could achieve a higher energy output than a square prism. [PERSON] et al. [42] presented a fork-shaped bluff body to improve the harvesting efficiency at low wind speed. The results demonstrated that a piezoelectric WEH with a fork-shaped structure could generate much higher output voltages than with the traditional bluff bodies, such as triangular prism and square prism. From the above literature review, it is noted that the energy harvesting efficiency from the fluid flow is improved through the shape of the bluff body. For the shape of the bluff body, most research work focus on experimental trails, to compare different cross sections and, thus, enhance the energy harvesting. A rare work designed the shape of the bluff body from the perspective of fluid dynamics. In the present study, an arc-plate-shaped bluff body is designed to improve the performance of a WEH. From a fluid dynamics point of view, the vortex reattachment decreases the lift force of the bluff body with a square cross-section. An arc-plate-shaped bluff body avoids the vortex reattachment and, thus, enhances the vibration. WEHs with arc-plate-shaped bluff bodies were tested in a wind tunnel. The Kriging surrogate model was established, accurately representing the mapping between the output power and the aerodynamic shape variables. The Kriging surrogate model is effective in shape optimization for discovering the change law and determining the optimal solution. The impacts of the shape modification on the efficiency of the WEH were evaluated.