On Boundary Conditions for Damage Openings in RoPax-Ship Survivability Computations

Abstract

The survivability of a damaged RoPax ship in the case of a flooding accident can be critical, as these ships have a tendency for a rapid capsize. Various simulation tools are presently in use to study the behavior of damaged RoPax and cruise ships. Recent benchmark tests show that the numerical tools for this purpose are very useful, but their accuracy and reliability still leave something to be desired. In many numerical simulation codes for ship survivability, the water inflow and outflow through a damage opening are modeled with Bernoulli equation, which describes steady flow in an inertial frame of reference. This equation takes neither the floodwater inertia in the opening into account nor does it regard the effect of ship motions on the flow in the opening. Thus, there are some approximations involved in the use of the Bernoulli equation for this purpose. Some alternative formulations are possible. This study sheds light on the question of how relevant is it to use the more complicated formulations instead of the very simple and robust Bernoulli model in the numerical simulation of damaged ships in the sea.