In computational fluid dynamics,
the **volume of fluid (VOF) method** is a numerical technique
for tracking and locating the free surface (or fluid-fluid interface).
It belongs to the class of Eulerian methods which are characterized by a
mesh
that is either stationary or is moving in a certain prescribed manner to
accommodate the evolving shape of the interface. As such, VOF is an
advection scheme—a numerical recipe that allows the programmer to track
the shape and position of the interface, but it is not a standalone flow
solving algorithm. The Navier–Stokes equations describing
the motion of the flow have to be solved separately. The same applies
for all other advection algorithms. [wikipedia]

There are several packages to apply the VOF method. At Deltares the package ComFlow is used, originally developed by the University of Groningen. In coastal engineering the modelling of the wave-structure interaction is one of the major applications of a VOF method.

At the department of Hydraulic Engineering of TU Delft we use IH2-VOF, developed by the University of Cantabria, which is a follow up of Cobras, developed by Cornell University. With this package we can in a very easy way model wave interaction with breakwaters.