# Algebraic Bounds on the Rayleigh-B\'enard attractor

## TL;DR

This paper establishes algebraic bounds on the Rayleigh-Bénard attractor's size using mathematical estimates, improving over previous bounds, and verifies these bounds with numerical simulations.

## Contribution

It introduces algebraic bounds on the Rayleigh-Bénard attractor using enstrophy estimates, enhancing the precision of previous estimates.

## Key findings

- Bounds are algebraic in viscosity and thermal diffusivity.
- Numerical simulations confirm the sharpness of the bounds.
- The approach simplifies analysis by using symmetry and boundary condition equivalences.

## Abstract

The Rayleigh-B\'enard system with stress-free boundary conditions is shown to have a global attractor in each affine space where velocity has fixed spatial average. The physical problem is shown to be equivalent to one with periodic boundary conditions and certain symmetries. This enables a Gronwall estimate on enstrophy. That estimate is then used to bound the $L^2$ norm of the temperature gradient on the global attractor, which, in turn, is used to find a bounding region for the attractor in the enstrophy, palinstrophy-plane. All final bounds are algebraic in the viscosity and thermal diffusivity, a significant improvement over previously established estimates. The sharpness of the bounds are tested with numerical simulations.