Contractive metrics for scalar conservation laws
F. Bolley, Y. Brenier, G. Loeper
TL;DR
The paper analyzes nondecreasing entropy solutions to 1-D scalar conservation laws and shows that their spatial derivatives, viewed as probability measures, satisfy a contraction with respect to the Wasserstein distance $W_p$ of any order, extending Kruzhkov's $L^1$ contraction to the derivative variable. The authors introduce an inverse-profile representation $X(t,w)$, solving $X_t=f'(u(t,X))$ so that $u(t,X(t,w))=w$ and $X_t(t,w)=f'(w)$, which yields $X- ilde X$ constant and hence time-invariance of $W_p(u_x, ilde u_x)$ for classical increasing solutions (and, for $p=1$, Kruzhkov-type contraction for the original profiles). They develop a time-discretization (Transport-Collapse) scheme with operators $T_h$ and $S_h$ that preserves the admissible classes, provides $W_p$-contraction for the spatial derivatives, and converges so $[S_h u^0]_x(t,.) o u_x(t,.)$ in $W_p$. The framework is extended to viscous conservation laws, establishing existence, uniqueness, and the same $W_p$ contraction for $u_x(t,.)$, with the inviscid limit obtained via vanishing viscosity and a discrete viscous scheme built from a heat kernel that preserves Wasserstein distances.
Abstract
We consider nondecreasing entropy solutions to 1-d scalar conservation laws and show that the spatial derivatives of such solutions satisfy a contraction property with respect to the Wasserstein distance of any order. This result extends the L^1-contraction property shown by Kruzkov.
