Parabolic Lipschitz truncation for multi-phase problems: the degenerate case
Bogi Kim, Jehan Oh, Abhrojyoti Sen
TL;DR
The paper addresses energy estimates for weak solutions to parabolic multi-phase problems with degenerate (nonlinear) growth governed by $H(z,\kappa)=\kappa^p+a(z)\kappa^q+b(z)\kappa^s$ and modulated coefficients $a(z), b(z)$. It introduces a parabolic Lipschitz truncation framework based on a Whitney decomposition and a phase-sensitive Vitali covering to construct Lipschitz test functions $v_h^\Lambda$, enabling a Caccioppoli-type inequality in a smaller cylinder controlled by data in a larger one plus a source term $F$. Key contributions include establishing Lipschitz regularity for the truncated test functions, deriving a parabolic Poincaré-type inequality, and obtaining robust energy bounds without requiring gradient higher integrability, under Hölder regularity of $a$ and $b$ and the condition $q\le p+\frac{2\alpha}{n+2}$, $s\le p+\frac{2\beta}{n+2}$. The framework extends elliptic double-phase Lipschitz truncation to the parabolic, degenerate regime, providing tools for existence and regularity theory in heterogeneous multi-phase media.
Abstract
This article is devoted to exploring the Lipschitz truncation method for parabolic multi-phase problems. The method is based on Whitney decomposition and covering lemmas with a delicate comparison scheme of appropriate alternatives to distinguish phases, as introduced by the first and the second author in [24].
