Quantized High-Performance High-Order Moment-Encoded LBM (arXiv preprint, 2026)

Yixin Chen1, Wei Li2,*, David I.W. Levin1,3, Kui Wu4

University of Toronto1, Shanghai Jiao Tong University2, NVIDIA3, LIGHTSPEED4
*Corresponding author
Teaser: turbulent smoke around an F1 car, fluid-only plumes at 1024^3, and jets through Hilbert-curve obstacles, simulated with our 16-bit quantized HOME-LBM solver.

Abstract

Lattice Boltzmann methods (LBM) are widely used for visually rich fluid simulation, but their high memory bandwidth and storage requirements limit GPU performance and scalability, especially when coupled with complex geometry. Recent high-order moment-encoded LBM (HOME-LBM) reduces memory cost by storing compact velocity moments and performing collision directly in moment space, but its tightly coupled boundary treatment introduces divergent control flow. We present a high-performance, quantized HOME-LBM framework for large-scale turbulent fluid–solid simulations on a single GPU. Our geometry-decoupled computation scheme separates the regular fluid update from a sparse solid-correction stage, isolating geometry-dependent computations to improve GPU efficiency. To further reduce storage and memory traffic, we develop a reduced-precision representation for HOME-LBM by combining von Neumann stability analysis, empirical moment-range estimation, and runtime decomposition of second-order moments to control quantization error. We evaluate our approach on real-time demonstrations and large-scale examples using both D3Q19 and D3Q27 lattices, with additional 2D and 3D numerical experiments assessing accuracy and stability. Across the tested benchmarks, our framework substantially accelerates the original FP32 HOME-LBM implementation, with a maximum speedup of 32.5× on the Hilbert-curve geometry. Moment storage is reduced by 50% in fluid-only simulations and 25% in fluid–solid coupling examples, while maintaining numerical stability, fidelity, and high visual quality. In the static delta-wing benchmark, our solver achieves a 5.2× speedup over Leapfrog Flow Maps (LFM) under the tested configuration.

Videos

Formula 1 car. Turbulent wake around a 5.3M-triangle F1 car on a 1000 × 400 × 400 grid (160M lattice cells). The whole simulation takes 368 s and 9.1 GB of GPU memory on a single NVIDIA RTX 4090, 5.8× faster than the original FP32 HOME-LBM [Li et al. 2023].
Hilbert-curve obstacles. Jet flow through progressively refined 3D space-filling Hilbert curves (levels 1–4, 15k to 145k triangles) on a 256 × 512 × 256 grid. Because the sparse solid correction is decoupled from the regular fluid update, the speedup over HOME-LBM grows from 6.2× to 32.5× as the geometry becomes more intricate.
Fluid-only plumes at 10243. 1.07 billion lattice cells simulated with our 16-bit quantized solver at Re = 40,960 (left) and Re = 2,048,000 (right). Moment storage is halved compared to the FP32 baseline while the solver stays stable at the high Reynolds number.
Delta wing at 0° and 20° angle of attack. Leapfrog Flow Maps [Sun et al. 2025] (left) and our solver (middle) on the same 256 × 128 × 128 grid with identical boundary conditions and visualization settings; an OpenFOAM LES result on the same surface mesh, visualized with Q-criterion isosurfaces, is shown on the right as a qualitative reference. Our solver is 5.2× faster than LFM in this configuration.

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