Trans RINA, Vol 157, Part A3, Intl J Maritime Eng, Jul-Sep 2015
Furthermore, within the simulation, the possibility of water spillage from the compartment has
been
introduced, if the head of water within the tank is:
Z eZ
cc 0
kZc
(7)
This relation can be satisfied, after the transient stage of flooding, when the wave through is passing above the damage hole.
The damaged compartment geometry is described by means of volumes and center of volume of the flooding water, implemented as look-up table within the numerical simulation model. The motions of the water within tank are assumed to be quasi-static, meaning that at each time the freesurface remains horizontal in the inertial frame. This assumption, in carrying out
the
applications, led also to neglect the acceleration of the lumped mass i
u . 3. THE SHIP MODEL
For the purpose of the applications, an example fast ferry has been used. The ship complies with the main standard practices for the Ro-ro pax mono –hulls and the subdivision for this vessel has been designed in order to satisfy the HSC code 2000/2009 damage stability criteria.
Table 2. Bottom damage dimensions
Areas vulnerable to raking damage HSC 2000/09 l1 (55%L) (m) 35.48
l2 (m) 22.58
p (m) 0.35
p (m) 0.17
g (m) 0.87
Areas not vulnerable to raking damage HSC 2000/09 l (m) 4.95
g (m) 1.74
4. Figure 2. 3D view of the ship subdivision. The 3D view of the ship is shown in Figure 2: it
represents a typical ferry operated in the “bay of Naples. In all the carried out
applications, the full loading
condition is assumed; the main characteristics of the ship are listed in Table 1.
Table 1. Main characteristics of the ship LOA LWL B D ∆
VCG GM
N° pax
N° ro-ro Range
71.06 m 64.54 m 13.40 m 8.5 m 650 t 5.17 2.32 530 40
350 NM
The main goal of this research work is the development of a numerical simulation model capable to predict the dynamic behaviour of a damaged fast ferry, in presence of longitudinal sea and heeling actions due to the wind.
Due to the lack of experimental tests on the ship model, preliminary numerical applications have been carried out in order to assess the reliability of the results. The comparison of
the results was performed with well- known numerical codes.
The initial ship equilibrium condition, for all the carried out computations, is assumed to be even-keel with a draft of
2.315 m, corresponding to the
displacement (see Table 1). 4.2
DECAY TEST
The first check, carried out on the intact hull, regards the ship response to initial perturbation for heave, pitch and roll. These tests are intended to analyse the transient stage of the dynamic system, mainly regarding damping actions.
full loading APPLICATIONS 4.1 PRELIMINARY CHECK Figure 3. Raking damage condition
All the damage scenarios of the sample vessel have been investigated according to the HSC code 2000/09 in a previous research work (Acanfora et alt. 2011). The sample damage condition assumed for the application is shown in Figure 3: it represents a damage scenario in the area vulnerable to raking damage (see Table 2), in the forepart of the vessel. This damage condition was also chosen in order to focus on the capability of the model in dealing with changes of trim during the flooding.
©2015: The Royal Institution of Naval Architects
A-155
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