Energy conservation in the limit of filtered solutions for the 2D Euler equations

TL;DR

This paper investigates energy conservation in weak solutions of the 2D Euler equations using a filtered approach, showing energy dissipation vanishes as the filter parameter tends to zero for certain vorticity integrability conditions.

Contribution

It demonstrates that filtered weak solutions with vorticity in L^p (p > 3/2) conserve energy in the limit, extending understanding of energy behavior in regularized Euler flows.

Findings

Energy dissipation rate converges to zero as filter parameter approaches zero for p > 3/2.

Filtered solutions satisfy a local energy balance in the distributional sense.

Similar results hold for p = 3/2 under Onsager's critical condition.

Abstract

We consider energy conservation in a two-dimensional incompressible and inviscid flow through weak solutions of the filtered-Euler equations, which describe a regularized Euler flow based on a spatial filtering. We show that the energy dissipation rate for the filtered weak solution with vorticity in $L^p$, $p > 3/2$ converges to zero in the limit of the filter parameter. Although the energy defined in the whole space is not finite in general, we formally extract a time-dependent part, which is well-defined for filtered solutions, from the energy and define the energy dissipation rate as its time-derivative. Moreover, the limit of the filtered weak solution is a weak solution of the Euler equations and it satisfies a local energy balance in the sense of distributions. For the case of $p = 3/2$, we find the same result as $p > 3/2$ by assuming Onsager's critical condition for the family of the filtered solutions.