Data from: Schlieren photography on freely flying hawkmoth

The aerodynamic force on flying insects result from the vortical flow structures that vary both spatially and temporally throughout flight. Due to these complexities and the inherent difficulties in studying flying insects in a natural setting, a complete picture of the vortical flow has been difficult to obtain experimentally. In this paper, Schlieren, a widely used technique for highspeed flow visualization, was adapted to capture the vortex structures around freely flying hawkmoth (Manduca). Flow features such as leading-edge vortex, trailing-edge vortex as well as the full vortex system in the wake was visualized directly. Quantification of the flow from the Schlieren images was then obtained by applying a physics-based optical flow method, extending the potential applications of the method to further studies of flying insects.

飞行昆虫所受的气动力，源于其飞行过程中在空间与时间维度上均存在动态变化的旋涡流动结构。鉴于此类流动的复杂性，以及在自然环境中研究飞行昆虫所固有的难度，通过实验手段完整获取这类旋涡流动的全貌始终颇具挑战。本文采用经改进的纹影（Schlieren）技术——一种广泛应用的高速流动可视化方法——对自由飞行的烟草天蛾（Manduca）周围的旋涡结构进行捕捉。研究直接可视化得到了前缘涡（leading-edge vortex）、后缘涡（trailing-edge vortex）以及尾迹完整旋涡系统等流动特征。随后，通过应用基于物理的光流法对纹影图像中的流动进行量化分析，将该方法的应用潜力拓展至飞行昆虫相关的后续研究中。