PIBNet: a Physics-Inspired Boundary Network for Multiple Scattering Simulations
R\'emi Marsal, St\'ephanie Chaillat

TL;DR
PIBNet is a physics-inspired graph neural network that efficiently approximates boundary solutions in multiple scattering problems, outperforming existing methods and generalizing well to complex obstacle configurations.
Contribution
We introduce PIBNet, a novel multiscale graph neural network architecture inspired by physics, for fast and accurate boundary solution approximation in multiple scattering simulations.
Findings
Outperforms state-of-the-art learning methods
Shows strong generalization to more obstacles
Efficiently models long-range interactions
Abstract
The boundary element method (BEM) provides an efficient numerical framework for solving multiple scattering problems in unbounded homogeneous domains, since it reduces the discretization to the domain boundaries, thereby condensing the computational complexity. The procedure first consists in determining the solution trace on the boundaries of the domain by solving a boundary integral equation, after which the volumetric solution can be recovered at low computational cost with a boundary integral representation. As the first step of the BEM represents the main computational bottleneck, we introduce PIBNet, a learning-based approach designed to approximate the solution trace. The method leverages a physics-inspired graph-based strategy to model obstacles and their long-range interactions efficiently. Then, we introduce a novel multiscale graph neural network architecture for simulating…
Peer Reviews
Decision·Submitted to ICLR 2026
1. Technically robust framework validated across three key PDEs (Helmholtz/Laplace), demonstrating high-fidelity prediction and a substantial inference time speedup of up to $200\times$. 2. It replaces the GMRES solver bottleneck in BEM by minimizing the Boundary Integral Equation (BIE) residual directly, creating a novel, physics-constrained acceleration method.
1. Generalization to Out-of-Distribution Inputs, different shapes not present in the training distribution (e.g., highly concave, asymmetric, or multiply connected domains). 2. Comparison to State-of-the-Art Accelerated BEM: The comparison is made against the standard, non-accelerated BEM (solving the dense BIE matrix). The authors should include a quantitative comparison against the gold standard for large-scale BEM: the Fast Multipole Method (FMM)-accelerated BEM. 3. Overall Cost Justificatio
- This work addresses neural boundary element method with multiple disjoint obstacles, which is an important and challenging task. - The technical and experimental parts are very solid. - The ablation study is very detailed and clear.
- The "Physics-Inspired" part of PIBNet is too weak, which is simply to choose the shortest edge among the candidates. - The neural network design is very similar to previous UNet-like meshgraphnet papers. Minor Issues: - I think there is a typo in the title of Section 3.1 "LEARNING AND BOUNDARY ELEMENT METHODS"
1. The experimental results show the high accuracy compared with the considered baselines, although the comparison is not complete (See Weakness 5).
1. The problem setting is unclear. The authors cite the reference for the multiple scattering problem, but it should be clearly formulated in the paper, as it is a central problem addressed in the work. 2. The difficulty of dealing with multiple obstacles is unclear. Since GNNs can handle arbitrary domains, there is no fundamental difficulty with multiple obstacles. There may be marginal difficulty arising from the increased complexity of the boundary, but this is not clearly stated in the paper
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Taxonomy
TopicsElectromagnetic Scattering and Analysis · Model Reduction and Neural Networks · Numerical methods in engineering
