On Equilibrium Shape of Charged Flat Drops

Cyrill B. Muratov (1) , Matteo Novaga (2) , Berardo Ruffini (3)

1 NJIT - Department of Mathematical Sciences [Newark, NJ]
2 Dipartimento di Matematica [Pisa]
3 IMAG - Institut Montpelliérain Alexander Grothendieck

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.

Domaines: Equations aux dérivées partielles [math.AP]; Physique mathématique [math-ph]

Cyrill B. Muratov, Matteo Novaga, Berardo Ruffini. On Equilibrium Shape of Charged Flat Drops. Communications on Pure and Applied Mathematics, 2018, 71 (6), pp.1049-1073. ⟨10.1002/cpa.21739⟩. ⟨hal-01819326⟩