Enhancement of Lagrangian slide lines as a combined force and velocity boundary condition

Many hydrodynamical problems involve shear flows along material interfaces. If the materials move along each other but are tied to a single Lagrangian computational mesh without any sliding treatment, severe mesh distortions appear which can eventually cause the failure of the simulation. This problem is usually treated by introducing the sliding line framework into the Lagrangian code. In this paper, we revise the 2D approach described in the article E.J. Caramana, The implementation of slide lines as a combined force and velocity boundary condition, Journal of Computational Physics 228 (2009), and suggest two enhancements – interpolated interaction instead of a simple one-to-one interaction described in the previous article, and a numerical surface tension model improving the stability of the interface. Both improvements stabilize the slide line and lead to more realistic results, as shown on selected numerical examples.