Research on passive deformation and hydrodynamic performance of a biomimetic cownose ray in gliding motion through fluid-structure interaction analysis.

This article investigates the effects of passive deformation of flexible pectoral fins on the hydrodynamic performance of cownose rays during gliding at various angles of attack (AoA) and fin stiffnesses. Using a coupled fluid-structure interaction (FSI) approach that integrates the incompressible Navier–Stokes equations solved via finite volume methods with structural deformation modeled by finite element methods, the study reveals that passive fin deformation increases both drag and lift while reducing pitching moment, thereby slightly improving the lift-to-drag ratio—most notably at an AoA of ±7.5°. The research further shows that lower pectoral fin stiffness leads to greater deformation, enhancing lift and stability during gliding. These findings provide insights relevant to the design of biomimetic underwater gliders, suggesting that incorporating flexible structures with optimized material properties can improve gliding efficiency and stability.