Hydrodynamic Analysis and Verification of an Innovative Whale Shark-like Underwater Glider

This paper presents an innovative design for a biomimetic whale shark-like underwater glider aiming at the combination of high maneuverability and long duration. As a hybrid of the underwater glider and the robotic fish, its pectoral fins and tail can serve as not only the external control surfaces for attitude regulation during gliding but also the propellers for agile fish-like swimming mode. To verify the gliding capability of the whale shark-like glider and prepare for future dynamic analysis, the hydrodynamic coefficients, including drag, lift, sliding force, and corresponding moments are estimated through computational fluid dynamics method. In addition, the hydrodynamic analyses of the proposed glider and an equivalent conventional glider during steady gliding motion are executed for comparison. Extended experiments are performed to verify the downward gliding performance. The results reveal that the whale shark-like glider has less drag as well as higher lift-to-drag ratio and a markable gliding capability in practice. It may offer important inspiration for improving the gliding efficiency and performance of an underwater glider in biomimetic shape design.