š¤ AI Summary
This work addresses the analytical and numerical challenges in singularity formation for partial differential equations such as the NavierāStokes and KellerāSegel systems. It proposes a unified framework integrating theoretical analysis with machine learning: by introducing vanishing modulation conditions and singularly weighted energy estimates, it streamlines and generalizes analytical proofs of blow-up solutions; furthermore, it pioneers the incorporation of KolmogorovāArnold Networks (KANs)āfeaturing learnable nonlinearities and strong interpretabilityāinto enhanced physics-informed neural networks (PINNs) and neural operators to accurately resolve singularity structures. The approach is successfully applied to the nonlinear heat equation, the complex GinzburgāLandau equation, and the three-dimensional KellerāSegel equation with logistic damping, resolving the long-standing open problem of singularity formation in the latter and offering new theoretical insights and efficient computational tools for investigating potential singularities in the NavierāStokes equations.
š Abstract
This thesis develops numerical and theoretical approaches for understanding and analyzing singularity formation in Partial Differential Equations (PDEs). The singularity formation in the Navier-Stokes Equation (NSE) is famously challenging as one of the seven Clay Prize problems. Unlike simpler equations such as the Nonlinear Heat (NLH) or Keller-Segel (KS) equations, where formal asymptotics near blowup are better understood, the intrinsic complexity of NSE makes quantitative analytical treatment difficult, if not impossible, without numerical guidance.
Building on numerical insights, we introduce a robust analytical framework to simplify and systematize pen-and-paper proofs for simpler singular PDEs. We present a novel approach based on enforcing vanishing modulation conditions for perturbations around approximate blowup profiles, complemented by singularly weighted energy estimates. We demonstrate the efficacy of our method on PDEs with complicated asymptotics, such as NLH and the Complex Ginzburg-Landau (CGL) equation, and address the open problem of singularity formation in the 3D KS equation with logistic damping.
We develop and refine numerical approaches that facilitate deeper insights into singularity formation. We demonstrate that machine learning methods significantly enhance our capability to identify and characterize potential blowup solutions with high precision. We improve on existing Physics-Informed Neural Network (PINN) and Neural Operator (NO) frameworks. Moreover, we present a novel machine learning paradigm, the Kolmogorov-Arnold Network (KAN) architecture, whose interpretability and excellent scaling properties are achieved through learnable nonlinearities.