  In this paper the hydrodynamics of fuselage models representing the main body
of three different types of aircraft, moving in water at constant speed and
fixed attitude is investigated using the Unsteady Reynolds-Averaged
Navier-Stokes (URANS) level-set flow solver $\chi$navis. The objective of the
CFD study is to give insight into the water landing phase of the aircraft
emergency ditching. The pressure variations over the wetted surface and the
features of the free surface are analysed in detail, showing a marked
difference among the three shapes in terms of the configuration of the thin
spray generated at the front. Such a difference is a consequence of the
different transverse curvature of the fuselage bodies. Furthermore, it is
observed that at the rear, where a change of longitudinal curvature occurs, a
region of negative pressure (i.e. below the atmospheric value) develops. This
generates a suction (downward) force of pure hydrodynamic origin. In order to
better understand the role played by the longitudinal curvature change on the
loads, a fourth fuselage shape truncated at the rear is also considered in the
study. The forces acting on the fuselage models are considered as composed of
three terms: the viscous, the hydrodynamic and the buoyancy contributions. For
validation purposes the forces derived from the numerical simulations are
compared with experimental data.
