Decay rate to the planar viscous shock wave for multi-dimensional scalar conservation laws

TL;DR

This paper analyzes the decay rate toward planar viscous shock waves in multi-dimensional scalar conservation laws, introducing a novel decomposition method and obtaining decay rates for all dimensions with minimal initial data restrictions.

Contribution

It introduces a new decomposition and anti-derivative approach to establish decay rates for multi-dimensional scalar viscous conservation laws with minimal initial data assumptions.

Findings

Decay rate for planar shock waves in all dimensions established.

Exponential decay rate for the non-zero mode obtained.

Initial perturbations only require belonging to H^2 and L^p spaces.

Abstract

In this paper, we study the time-decay rate toward the planar viscous shock wave for multi-dimensional (m-d) scalar viscous conservation law. We first decompose the perturbation into zero and non-zero mode, and then introduce the anti-derivative of the zero mode. Though an $L^p$ estimate and the area inequality introduced in \cite{DHS2020}, we obtained the decay rate for planar shock wave for n-d scalar viscous conservation law for all $n\geq1$. The initial perturbations we studied are small, i.e., $\|\Phi_0\|_{H^2}\bigcap\|\Phi_0\|_{L^p}\le \varepsilon$, where $\Phi_0$ is the anti-derivative of the zero mode of initial perturbation and $\varepsilon$ is a small constant, see \cref{antiderivative}. It is noted that there is no additional requirement on $\Phi_0$, i.e., $\Phi_0(x_1)$ only belongs to $H^2(\R)$. Thus, there are essential differences from previous results, in which the initial data is required to belong to some weighted Sobolev space, cf.\cite{Goo1989,KM1985}. Moreover, the exponential decay rate of the non-zero mode is also obtained.