# Nonlinear inviscid damping for zero mean perturbation of the 2D Euler Couette flow

## TL;DR

This paper revisits and refines the proof of nonlinear inviscid damping for zero mean perturbations of the 2D Euler Couette flow, emphasizing the mathematical techniques and assumptions involved.

## Contribution

It provides a detailed analysis of the inviscid damping proof under zero mean conditions, highlighting the control of echoes via an approximation of the weight.

## Key findings

- Strong convergence of small perturbations to zero in the flow
- Control of echoes through weight approximation
- Clarification of mathematical techniques for nonlinear damping

## Abstract

In this note we revisit the proof of Bedrossian and Masmoudi [arXiv:1306.5028] about the inviscid damping of planar shear flows in the 2D Euler equations under the assumption of zero mean perturbation. We prove that a small perturbation to the 2D Euler Couette flow in $\mathbb{T}\times \mathbb{R}$ strongly converge to zero, under the additional assumption that the average in $x$ is always zero. In general the mean is not a conserved quantity for the nonlinear dynamics, for this reason this is a particular case. Nevertheless our assumption allow the presence of echoes in the problem, which we control by an approximation of the weight built in [arXiv:1306.5028]. The aim of this note is to present the mathematical techniques used in [arXiv:1306.5028] and can be useful as a first approach to the nonlinear inviscid damping.