This course intends to give the students some insight on the simulation of immiscible incompressible 2 phases flow with the Navier-Stokes equations. The physical model described is the 1-fluid model with the VOF method to track the interface. The course reviews the basic equations, the finite volume discretization and the VOF methods. Finally an introduction to the numerical model OpenFoam is given with a focus on InterFoam, the two phase flow module of the former software. A significant amount of time is then devoted to the tutorial of openFoam leading to a project that the student have to complete with a report at the end of the course.