Chaoyang Lyu

Over the past decade, the Lattice Boltzmann Method (LBM) has matured into a leading framework for high-performance fluid simulation across research and industry alike. Its appeal rests on a set of properties that align unusually well with the demands of modern computing: collision and streaming operators that are strictly local, mapping naturally onto massively parallel architectures; an intrinsic ability to handle complex geometries through simple boundary rules; and a level of physical fidelity that has proven sufficient across a widening range of applications — from real-time simulation and visual effects to large-scale industrial tools such as virtual wind tunnels. The growing body of LBM-based work at SIGGRAPH and SIGGRAPH Asia reflects this trajectory directly: the method has moved from occasional appearance to recurring presence as a core computational framework.Despite this prominence, LBM has never been the subject of a dedicated SIGGRAPH course. To date, it has only been mentioned peripherally, most notably as a small component of the Real-Time Physics course at SIGGRAPH 2004. As a result, there remains a significant gap between the method’s practical importance and its formal coverage within the SIGGRAPH educational program. This lack of structured exposure has made it difficult for practitioners and researchers to fully understand the method’s foundations, strengths, limitations, and best practices for deployment on contemporary hardware. These course notes are an attempt to close that gap. Written by authors with direct experience across multiple LBM publications at SIGGRAPH over the past six years, they aim to provide something the existing literature rarely offers in a single place: a coherent path from first principles to production-oriented practice. The intent is not to survey recent work, but to equip attendees with the concepts, implementation details, and the critical perspective needed to start working with LBM solvers.

Virtual wind tunnel testing is a key ingredient in the engineering design process for the automotive and aeronautical industries as well as for urban planning: through visualization and analysis of the simulation data, it helps optimize lift and drag coefficients, increase peak speed, detect high pressure zones, and reduce wind noise at low cost prior to manufacturing. In this paper, we develop an efficient and accurate virtual wind tunnel system based on recent contributions from both computer graphics and computational fluid dynamics in high-performance kinetic solvers. Running on one or multiple GPUs, our massively-parallel lattice Boltzmann model meets industry standards for accuracy and consistency while exceeding current mainstream industrial solutions in terms of efficiency — especially for unsteady turbulent flow simulation at very high Reynolds number (on the order of 107) — due to key contributions in improved collision modeling and boundary treatment, automatic construction of multiresolution grids for complex models, as well as performance optimization. We demonstrate the efficacy and reliability of our virtual wind tunnel testing facility through comparisons of our results to multiple benchmark tests, showing an increase in both accuracy and efficiency compared to state-of-the-art industrial solutions. We also illustrate the fine turbulence structures that our system can capture, indicating the relevance of our solver for both VFX and industrial product design.

The intricate motions and complex vortical structures generated by the interaction between fluids and solids are visually fascinating. However, reproducing such a two-way coupling between thin objects and turbulent fluids numerically is notoriously challenging and computationally costly: existing approaches such as cut-cell or immersed-boundary methods have difficulty achieving physical accuracy, or even visual plausibility, of simulations involving fast-evolving flows with immersed objects of arbitrary shapes. In this paper, we propose an efficient and versatile approach for simulating two-way fluid-solid coupling within the kinetic (lattice-Boltzmann) fluid simulation framework, valid for both laminar and highly turbulent flows, and for both thick and thin objects. We introduce a novel hybrid approach to fluid-solid coupling which systematically involves a mesoscopic double-sided bounce-back scheme followed by a cut-cell velocity correction for a more robust and plausible treatment of turbulent flows near moving (thin) solids, preventing flow penetration and reducing boundary artifacts significantly. Coupled with an efficient approximation to simplify geometric computations, the whole boundary treatment method preserves the inherent massively parallel computational nature of the kinetic method. Moreover, we propose simple GPU optimizations of the core LBM algorithm which achieve an even higher computational efficiency than the state-of-the-art kinetic fluid solvers in graphics. We demonstrate the accuracy and efficacy of our two-way coupling through various challenging simulations involving a variety of rigid body solids and fluids at both high and low Reynolds numbers. Finally, comparisons to existing methods on benchmark data and real experiments further highlight the superiority of our method.