Multiphysics Bench: Benchmarking and Investigating Scientific Machine Learning for Multiphysics PDEs
Changfan Yang, Lichen Bai, Yinpeng Wang, Shufei Zhang, Zeke Xie

TL;DR
This paper introduces a comprehensive multiphysics PDE dataset, evaluates existing machine learning solvers on multiphysics problems, and provides insights and techniques to improve their performance in complex coupled systems.
Contribution
It presents the first multiphysics dataset, systematically investigates existing ML PDE solvers on these problems, and offers practical insights and tricks for better solutions.
Findings
Naive application of existing solvers performs poorly on multiphysics problems.
The Multiphysics Bench dataset is the most comprehensive to date.
Several useful techniques are identified to enhance multiphysics PDE solving with ML.
Abstract
Solving partial differential equations (PDEs) with machine learning has recently attracted great attention, as PDEs are fundamental tools for modeling real-world systems that range from fundamental physical science to advanced engineering disciplines. Most real-world physical systems across various disciplines are actually involved in multiple coupled physical fields rather than a single field. However, previous machine learning studies mainly focused on solving single-field problems, but overlooked the importance and characteristics of multiphysics problems in real world. Multiphysics PDEs typically entail multiple strongly coupled variables, thereby introducing additional complexity and challenges, such as inter-field coupling. Both benchmarking and solving multiphysics problems with machine learning remain largely unexamined. To identify and address the emerging challenges in…
Peer Reviews
Decision·Submitted to ICLR 2026
- Multi physics problems are widely present in the real-world. highly Creating a standardized, multi-scenario multiphysics benchmark is valuable for the SciML community; the chosen scenarios are relevant to real applications (electronics, fluid/thermal systems, acoustics, porous-media transport). - Many different PDEs are included in the benchmark with different initial and boundary conditions, although there are a few omissions. - Evaluation of four major solver families (PINNs, DeepONet, FNO
Major Weakness: The scientific contribution of the paper is unclear. - The multiphysics benchmark dataset does not focus on what sets multiphysics problems apart from single-physics problems (cross-field interactions, different spatio/temporal scales across fields, etc.). Simply measuring global reconstruction error does not inform us why SciML methods might fail on multiphysics problems or how to fix them? - The empirical takeaway is essentially that existing SciML models for PDEs generali
1. This paper systematically focuses on the critical and complex domain of coupled multiphysics PDEs. The inclusion of diverse and challenging coupling types (bidirectional/unidirectional, equation/parameter-level) demonstrates an original and comprehensive problem formulation that accurately reflects real-world engineering and science. 2. The authors use four leading learning-based PDE solvers (PINN, FNO, DeepONet, and DiffusionPDE) on all six problems 3. The problems are deliberately chosen to
1. The paper needs to explain why the relative $L_2$ error performance of baseline models remains unchanged (or nearly unchanged) despite a significant increase in the data scale (number of training samples) in Table 4. 2. The paper correctly identifies various failure modes (e.g., FNO mode collapse, PINN gradient inconsistency), but the justification is often descriptive rather than quantitatively analytical.
A new problem that has practical implications for modeling multi-physics systems.
It may not be of general interest.
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