Rigid Body Dynamics in Ambient Fluids

TL;DR

This paper introduces a new, efficient framework for simulating rigid body motion in fluids that accurately captures complex behaviors like fluttering and tumbling without complex fluid simulations.

Contribution

It provides a generalized, shape-independent estimate of flow effects, enabling realistic and real-time rigid body dynamics in ambient fluids.

Findings

Reproduces full range of falling plate behaviors

Captures phenomena like Magnus effect and spiral passes

Compatible with existing physics engines

Abstract

We present a novel framework for rigid body dynamics in ambient media, such as air or water, enabling accurate motion prediction of objects without requiring computational fluid dynamics simulations. Our method computes the added mass of the fluid and replaces heuristic models for shape-dependent lift and drag with a generalized estimate of flow separation and dynamic pressure. Our method is the first within the rigid body dynamics context to reproduce the full range of falling plate behaviors: fluttering, tumbling, chaotic and steady modes, as well as phenomena such as the Magnus effect and the flight dynamics of an American football (tight spiral pass paradox). The resulting algorithm is simple to implement, robust, does not rely on specialized integrators and incorporates seamlessly into existing physics engines for real-time simulation.