Meeting Abstract
This work uses a physics-based model of a swimming bottlenose dolphin to investigate thrust production and propulsive efficiency. The model captures critical features such as body posture, fluke flexibility, and delayed fluke stalls, and integrates findings from previous research on small odontocetes, including body morphometry, fluke morphology and elasticity, gait and swimming stability. The modeling framework is based on a mixed Newtonian-Lagrangian formulation and brings together tools and concepts from multi-body dynamics, plate theory, hydroelasticity, and unsteady hydrodynamics. The head, torso, caudal peduncle, and pectoral fins are modeled as a set of interconnected rigid bodies subject to a prescribed kinematic gait profile relative to the torso. Gait kinematics are extracted from video data of bottlenose dolphins swimming over a range of speeds. The fluke, on the other hand, is modeled as a flexible plate, whose deformation evolves in response to hydrodynamic, elastic, and inertial forces acting on the fluke. Because hydrodynamic loading over the fluke is in turn affected by its deformation state, the model incorporates results from unsteady thin-airfoil theory and unsteady lifting-line theory to predict lift and drag distributions over the deforming body. An inverse dynamics analysis is used to estimate forces, moments, and power required to move elements of the model during the experimentally derived motion. We show that the swimming kinematics resulting from our model are in good agreement with kinematic data previously reported in the literature. We also present estimates of swimming energetics over a wide range of speeds, and compare these results with estimates obtained from previous work on cetacean swimming performance and oscillating hydrofoil propulsors. Finally, we discuss discrepancies between our findings and existing knowledge of the hydrodynamic performance of a swimming dolphin.
