A Nonlinear Wave Equation in Free Capillary Surface Flows

In the study of free capillary flows, one comes across the nonlinear wave equation


which has the associated conserved energy functional

The following are movies of solutions of this equation when the domain is disk and the equation was discretized using a second order in time, centered finite difference in time and piecewise linear element in space scheme. Solutions of the numerical scheme are guaranteed to be energy nonincreasing (although they are energy decreasing in practice due to numerical diffusion). This boundary value problem is well posed for initial data which lie in the space BV.