Predicting Physics in Mesh-reduced Space with Temporal Attention

XU HAN, Han Gao, Tobias Pfaff, Jian-Xun Wang, Liping Liu

Keywords: fluid dynamics, graph neural network, attention neural network

Abstract: Auto-regressive sequence models for physics prediction are often restricted to low-dimensional systems, as memory cost increases with both spatial extents and sequence length. On the other hand, graph-based next-step prediction models have recently been very successful in modeling complex high-dimensional physical systems on irregular meshes, but suffer from error accumulation and drift, due to their short temporal attention span. In this paper, we present a method that marries the strengths of both approaches. We use a GNN to locally summarize features and create coarsened, compact mesh representation of the system state, onto which we apply a transformer-style temporal attention module. We use a second GNN to decode these predictions back to a full-sized graph and perform fine-scale updates. Our method outperforms a competitive GNN baseline on three complex fluid dynamics prediction tasks, from sonic shocks to vascular flow. We demonstrate stable rollouts without the need for training noise and show perfectly phase-stable predictions even for very long sequences. More broadly, we believe our approach paves the way to bringing the benefits of attention-based sequence models to solving high-dimensional complex physics tasks.

One-sentence Summary: We use a GNN to locally summarize features and create coarsened, compact mesh representation of the system state, onto which we apply a transformer-style temporal attention module for physics prediction.