Model coupling techniques for free-surface flow problems. Part I.

The motion of water in a complex hydrodynamic configuration is characterized by a wide spectrum of space and time scales, due to the coexistence of physical phenomena of different nature. Conse- quently, the numerical simulation of a hydrodynamic system of this type is characterized by a large computational cost. In this paper, after providing a quite general setting for model coupling, we intro- duce a first possible technique to reduce such a computational effort, by suitably coupling different hydrodynamic models, namely a dimensionally heterogeneous–physically homogeneous coupling strategy, driven by a priori physical considerations. The aim of this paper is to investigate in more detail the range of reliability of this approach moving from suitable test cases. A second strategy, based on a dimensionally homogeneous–physically heterogeneous coupling, will be provided in the second part of this work