Calculus of Variations and Geometric Measure Theory

C. Muratov - M. Novaga - B. Ruffini

On equilibrium shapes of charged flat drops

created by ruffini on 18 Jul 2016
modified by novaga on 20 Apr 2018


Published Paper

Inserted: 18 jul 2016
Last Updated: 20 apr 2018

Journal: Comm. Pure Appl. Math.
Volume: 71
Number: 6
Pages: 1049-1073
Year: 2018


Equilibrium shapes of two-dimensional charged, perfectly conducting liquid drops are governed by a geometric variational problem that involves a perimeter term modeling line tension and a capacitary term modeling Coulombic repulsion. Here we give a complete explicit solution to this variational problem. Namely, we show that at fixed total charge a ball of a particular radius is the unique global minimizer among all sufficiently regular sets in the plane. For sets whose area is also fixed, we show that balls are the only minimizers if the charge is less than or equal to a critical charge, while for larger charge minimizers do not exist. Analogous results hold for drops whose potential, rather than charge, is fixed.