FluxNet通过学习局部传输量实现精确守恒与边界保持的物理模拟。
FluxNet: Learning Capacity-Constrained Local Transport Operators for Conservative and Bounded PDE Surrogates
- 基于累计传输量设计,直接保证离散守恒
- 在四种基准上实现零误差守恒与边界约束
- 适合需要大时间步长和高精度守恒的物理仿真
自回归式时间步进算子在数据驱动的偏微分方程(PDE)模拟中表现高效,但对守恒律问题存在根本挑战:长期滚动预测中学习到的更新可能破坏全局守恒。对于质量守恒类方程,该问题因固有物理边界(如非负性或浓度在[0,1]区间)的违反而加剧,进一步导致预测不稳定。本文提出FluxNet,通过学习每个单元与可配置邻域间在整个代理区间内累计传输的守恒量,实现构造性离散守恒。模块化容量受限的传输头(L、U、D)通过架构设计分别强制下界、上界或近似零双界违反。与需时间积分并继承CFL限制的通量率代理不同,FluxNet无需积分;可配置的传输邻域支持全空间分辨率下的大时间步预测。幽灵单元扩展框架至非周期边界。在四个基准测试(一维对流-扩散、二维浅水方程、一维交通流、二维Cahn-Hilliard)上验证了精确守恒、结构边界保持、架构模块化及在大时间步长下优于通量率代理的稳定性。代码已公开于:https://github.com/Lan-zs/FluxNet。
原文摘要 · Abstract (English)
Autoregressive learning of time-stepping operators provides an effective approach to data-driven partial differential equation (PDE) simulation, yet for conservation laws, they face a fundamental challenge: learned updates may violate global conservation over long rollouts. For the important subclass of mass-conservation-type equations, the problem is compounded by inherent physical bounds (e.g., nonnegativity or concentrations in [0,1]) whose violation further destabilizes predictions. We introduce FluxNet, which learns cumulative transport amounts representing the total conserved quantity redistributed between each cell and a configurable neighborhood over the full surrogate interval. A conservative update guarantees exact discrete conservation by construction; modular capacity-constrained transport heads (L, U, and D) enforce lower bounds, upper bounds, or near-zero dual-bound violations through architectural design. Unlike flux-rate surrogates that require temporal integration and thus inherit CFL constraints, FluxNet involves no such integration; configurable transport neighborhoods enable large-timestep prediction at full spatial resolution. Ghost cells extend the framework to non-periodic boundaries. Experiments on four benchmarks (1D convection--diffusion, 2D shallow water, 1D traffic flow, 2D Cahn--Hilliard) demonstrate exact conservation, structural bound preservation, architecture modularity, and superior stability over flux-rate surrogates at large temporal strides. The code is publicly available at: https://github.com/Lan-zs/FluxNet.
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