Conservation laws with nonlocal velocity -- the singular limit problem

TL;DR

This paper studies the convergence of solutions to nonlocal conservation laws with exponential weights towards local entropy solutions as the nonlocal weight becomes a Dirac delta, establishing uniform estimates and entropy admissibility.

Contribution

It proves convergence of nonlocal solutions to local entropy solutions for exponential weights and general kernels, highlighting the importance of monotonicity and tailored entropy flux pairs.

Findings

Solutions converge to local entropy solutions as nonlocal weight approaches a Dirac delta.

Uniform total variation estimates enable proof of entropy admissibility in the limit.

Monotonicity of initial data is preserved, ensuring convergence for general kernels.

Abstract

We consider conservation laws with nonlocal velocity and show for nonlocal weights of exponential type that the unique solutions converge in a weak or strong sense (dependent on the regularity of the velocity) to the entropy solution of the local conservation law when the nonlocal weight approaches a Dirac distribution. To this end, we establish first a uniform total variation estimate on the nonlocal velocity which enables it to prove that the nonlocal solution is entropy admissible in the limit. For the entropy solution, we use a tailored entropy flux pair which allows the usage of only one entropy to obtain uniqueness (given some additional constraints). For general weights, we show that monotonicity of the initial datum is preserved over time which enables it to prove the convergence to the local entropy solution for rather general kernels and monotone initial datum as well. This covers the archetypes of local conservation laws: Shock waves and rarefactions. It also underlines that a ``nonlocal in the velocity'' approximation might be better suited to approximate local conservation laws than a nonlocal in the solution approximation where such monotonicity does only hold for specific velocities.