Implicit Surface Tension Formulation with a Lagrangian Surface mesh on an Eulerian Simulation Grid

We present a method for applying implicit forces on a Lagrangian mesh to an Eulerian discretization of the Navier Stokes equations in a way that produces a sparse symmetric positive definite system. The resulting method has implicit and fully coupled viscosity, pressure, and Lagrangian forces. We apply our new framework for forces on a Lagrangian mesh to the case of surface tension force, which when treated explicitly leads to a tight ∆t = O(∆x) time step restriction. By applying surface tension as an implicit Lagrangian force, the resulting method benefits from improved stability and the ability to take larger time steps. The resulting discretization is also able to maintain parasitic currents at low levels.