The relaxed area of $\mathcal{S}^1$-valued singular maps in the strict $BV$-convergence

Abstract

Given a bounded open set $\Omega \subset \mathbb{R}^2$, we study the relaxation of the nonparametric area functional in the strict topology in $BV(\Omega;\mathbb{R}^2)$, and compute it for vortex-type maps, and more generally for maps in $W^{1,1}(\Omega;\mathcal{S}^1)$ having a finite number of topological singularities. We also extend the analysis to some specific piecewise constant maps in $BV(\Omega;\mathcal{S}^1)$, including the symmetric triple junction map.