Abstract
Simulating multi-rigid-body interactions in underwater environments is crucial for various downstream applications, such as robotic navigation, manipulation, and locomotion. However, existing approaches either rely on computationally expensive volumetric fluid-rigid simulations or focus solely on single-body dynamics. In this work, we introduce a fast framework for simulating multi-rigid-body coupling in underwater environments by extending the added mass paradigm to capture global interactions in incompressible, irrotational fluids. Our method solves a Boundary Integral Equation (BIE) for the potential flow field, from which we derive the governing equation of motion for multiple underwater rigid bodies using a variational principle. We evaluate our method across a range of underwater tasks, including object gripping and swimming. Compared to state-ofthe- art volumetric fluid solvers, our approach consistently reproduces similar behaviors while achieving up to 13× speedup. The example source code is available at https://github.com/guesss2022/fastMBCUI.
