On the decay and Gevrey regularity of the solutions to the Navier-Stokes equations in general two-dimensional domains
Raphaël Danchin
TL;DR
The paper develops an elementary, energy-method framework to derive time-decay estimates for derivatives of all orders of finite-energy solutions to the 2D incompressible Navier–Stokes equations in general domains. By combining energy estimates with the Ladyzhenskaya inequality, it obtains Gevrey-type regularity and decay results that hold for small data and extend to large data via renormalization techniques, without relying on Fourier analysis. It furthermore establishes short-time Gevrey regularity for large data through a Stokes–fluctuation decomposition and demonstrates faster decay under assumed $L^2$-decay of the solution. The work provides explicit a priori bounds and decay rates for time derivatives in 2D, applicable to general domains, and highlights a unified method linking decay, regularity, and domain-general analysis.
Abstract
The present paper is devoted to the proof of time decay estimates for derivatives at any order of finite energy global solutions of the Navier-Stokes equations in general two-dimensional domains. These estimates only depend on the order of derivation and on the L2 norm of the initial data. The same elementary method just based on energy estimates and Ladyzhenskaya inequality also leads to Gevrey regularity results.
