Simulation of free feather behavior

We present a general framework for simulating the behaviors of free feather like objects inside a dynamic changing flow field. Free feathers demonstrate beautiful dynamics, as they float, flutter, and twirl in response to lift and drag forces created by its motion relative to the flow. To simulate its movement in 2D, we adopt the thin strip model to account for the effect of gravity, lift and inertial drag. To achieve 3D animations, we implement two methods. For the first approach, we extend the thin strip model, use either flow primitive or noise functions to construct a time-varying flow field and extract external forces to update the thin strip computation. For the second approach, we implement a physically based simulation of the flow field and adopt the momentumexchange method to evaluate the body force on the feather. As a result, the natural flutter, tumble, gyration dynamics emerge and vortices are created all in response to local surface-flow interactions without the imposition of the thin strip model.