Modeling And Analysis of Variable Buoyancy Device Imitating Waterfowl Plumage Structure

Aquatic birds can vary density autonomously in diving by changing the physical condition of the plumage. The variation of plumage determines the whole body’s buoyancy when diving. In this paper, plume compression ratio of domestic ducks is quantitatively measured, and a variable buoyancy device that imitates the plumage structure of waterfowl is proposed. The device consists of two components, namely flexible and rigid body part. Three mathematical models of positive buoyancy force varying with diving depth were built for the following three simulation scenarios, flexible body part filled with air only, mixture of air and feathers under airtight and airtightless conditions, respectively. Simulation results suggest that, the scenario when flexible part is filled with mixture of air and feathers under airtight condition results in the best diving performance, free suspended depth could reach a maximum value of 7.4 m, and positive buoyancy force ranges between -43 N and 43.2 N. Simulation results show the effectiveness of bionic variable buoyancy device.