Learned Adaptive Mesh Generation

Abstract: The distribution and evolution of several real-world quantities, such as temperature, pressure, light, and heat, are modelled mathematically using Partial Differential Equations (PDEs). Solving PDEs defined on arbitrary 3D domains, say a 3D scan of a turbine's blade, is computationally expensive and scales quadratically with discretization. Traditional workflows in research and industry exploit variants of the finite element method (FEM), but some key benefits of using Monte Carlo (MC) methods have been identified. We use sparse and approximate MC estimates to infer adaptive discretization. We achieve this by training a neural network that is lightweight and that generalizes across shapes and boundary conditions. Our algorithm, Learned Adaptive Mesh Generation (LAMG), maps a set of sparse MC estimates of the solution to a sizing field that defines a local (adaptive) spatial resolution. We then use standard methods to generate tetrahedral meshes that respect the sizing field, and obtain the solution via one FEM computation on the adaptive mesh. We train the network to mimic a computationally expensive method that requires multiple (iterative) FEM solves. Thus, our one-shot method is $2\times$ to $4\times$ faster than adaptive methods for FEM or MC while achieving similar error. Our learning framework is lightweight and versatile. We demonstrate its effectiveness across a large dataset of meshes.