融合物理规律的神经微分模型,实现边界流场长期稳定高效预测。
Physics-integrated neural differentiable modeling for immersed boundary systems
- 将物理约束嵌入可微架构,用学习修正替代昂贵压力投影。
- 单步监督训练,1小时内完成,支持粗网格大时间步长推理。
- 在雷诺数100下显著优于纯数据或传统数值方法,推理快200倍。
精确、高效且稳定地计算复杂流体在固体边界附近的长期演化仍具挑战。传统数值求解器需细网格和小时间步,计算成本高;纯数据驱动模型则累积滚动误差,外推时鲁棒性差。本文提出一种融合物理的神经微分框架,用于浸入边界流的长期预测。核心设计包括:基于偏微分方程的中间速度模块与多向力浸入边界模块,均遵循不可压缩流的压力投影流程;以ConvResNet块学习隐式修正代替耗时的压力投影,降低计算成本;引入子迭代策略,使物理模块稳定性与代理模型时间步分离,实现粗网格下的稳定自回归滚动。模型仅需单步监督训练,无需长时间反向传播,在单个GPU上训练时间不足一小时。在雷诺数100的静止圆柱与旋转振荡圆柱基准测试中,该模型在流场保真度和长期稳定性上持续优于纯数据驱动、物理损失约束及粗网格数值基线,同时相较高分辨率求解器实现约200倍的推理加速。
原文摘要 · Abstract (English)
Accurately, efficiently, and stably computing complex fluid flows and their evolution near solid boundaries over long horizons remains challenging. Conventional numerical solvers require fine grids and small time steps to resolve near-wall dynamics, resulting in high computational costs, while purely data-driven surrogate models accumulate rollout errors and lack robustness under extrapolative conditions. To address these issues, this study extends existing neural PDE solvers by developing a physics-integrated differentiable framework for long-horizon prediction of immersed-boundary flows. A key design aspect of the framework includes an important improvement, namely the structural integration of physical principles into an end-to-end differentiable architecture incorporating a PDE-based intermediate velocity module and a multi-direct forcing immersed boundary module, both adhering to the pressure-projection procedure for incompressible flow computation. The computationally expensive pressure projection step is substituted with a learned implicit correction using ConvResNet blocks to reduce cost, and a sub-iteration strategy is introduced to separate the embedded physics module's stability requirement from the surrogate model's time step, enabling stable coarse-grid autoregressive rollouts with large effective time increments. The framework uses only single-step supervision for training, eliminating long-horizon backpropagation and reducing training time to under one hour on a single GPU. Evaluations on benchmark cases of flow past a stationary cylinder and a rotationally oscillating cylinder at Re=100 show the proposed model consistently outperforms purely data-driven, physics-loss-constrained, and coarse-grid numerical baselines in flow-field fidelity and long-horizon stability, while achieving an approximately 200-fold inference speedup over the high-resolution solver.
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