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A comprehensive description of the FloodW Simulation Code and its applications
Published in Selma Ergin, C. Guedes Soares, Sustainable Development and Innovations in Marine Technologies, 2022
M. Acanfora, M. Altosole, T. Coppola, R. Martino
The barge model was tested with two initial stability conditions; among these, one is characterized by a small metacentric height (GMsmall), responsible for complex coupling phenomena between ship and flooded water dynamics, close to the instability range. For the purpose of this application, the GMsmall is assumed. The study under consideration regards the roll decay test of the barge, carried out at three different fillings (relevant in the range of shallow water and intermediate filling levels) of the flooded compartment that is symmetric to the center plane. The damaged hole is closed, thus there is no water exchange with the sea. The results of the application of the ME and the GA method are compared with the experimental data (EXP) in Figure 4. It can be observed that the GA approach is fairly accurate and robust for any analyzed filling level. On the other hand, the ME technique ensures a better agreement for small fillings i.e. 2.5 kg and 5 kg, in the shallow water range, despite increasing gaps with the increase of the filling level.
Introduction to fluid mechanics
Published in Mike Tooley, Lloyd Dingle, Engineering Science, 2020
A body is considered unstable if a small displacement tends to cause a turning moment that displaces the body further from its equilibrium position. A body is considered to have neutral stability when it remains at rest in the position to which it was disturbed. With respect to boats, we are primarily concerned with the ability of the vessel to return to its equilibrium position after rolling (its lateral stability). When it rotates about its longitudinal axis, this type of built-in stability is important to avoid the boat capsizing! With aircraft, stability in pitch, that is stability about the lateral axis, and stability in yaw, that is stability about the vertical or normal axis, is also important. We will now consider the stability conditions for equilibrium of a boat.
Semi-dynamic ship domain in the encounter situation of two vessels
Published in C. Guedes Soares, Developments in the Collision and Grounding of Ships and Offshore Structures, 2019
M. Gil, J. Montewka, P. Krata, T. Hinz, S. Hirdaris
Another important point to raise is the subjectivity of those proximity indicators. They refer to the comfort area defined by a navigator rather than a safety-critical area for a ship to perform evasive action. The difference between comfort and critical areas is substantial. Therefore, a navigator handling a ship should be aware of the safety dimensions of the area or reversely on its critical size. This information arises as a necessity when planning an evasive maneuver in an encounter, where the other, give-a-way vessel is not acting as supposed. This critical area depends on numerous factors, where the ship dynamics is one of them, and only a few studies address this issue, see for example (Colley, et al. 1983; Curtis 1986; Montewka, et al. 2012a; Zhang et al. 2012; Łukaszewicz 2007; Szlapczynski & Krata 2018). In our earlier works, (Krata & Montewka 2015; Montewka & Krata 2014), we present a model determining the critical area for a Ro-pax ship, accounting for her dynamics, preselected stability conditions and simplified encounter type. However, these studies face serious limitations, by considering one type of maneuver for fixed rudder settings (turning circle at 20° angle), one type of ship, and presumably favorable stability and weather conditions.
Consequence analyses of collision-damaged ships — damage stability, structural adequacy and oil spills
Published in Ships and Offshore Structures, 2023
Artjoms Kuznecovs, Jonas W. Ringsberg, Anirudh Mallaya Ullal, Pavan Janardhana Bangera, Erland Johnson
This code can be used directly to evaluate a damaged ship’s stability conditions, e.g. the roll motions of the ship and how they change due to flooding and acting waves. The time-varying section hydrodynamic forces along the hull and the change in total mass distribution (see above) are coupled to the URSA code in a sequentially coupled approach. By doing so, the structural response assessment and the hull’s structural adequacy account for the change in section forces due to the ship’s motions and change in mass distribution. This coupling is highly relevant for the consequence analysis of the damaged ship’s structural integrity. To get representative results of ship motions and damage stability especially in case of extreme events, multiple realizations of irregular waves should be considered. However, in this study for the purpose of showcasing the framework, a single realisation of irregular waves for stability simulations was considered as sufficient and direct assessment of threshold values’ exceedance (see below) was employed.
A Geotechnical Analysis to Assess the Effect of Slow-Moving Landslides on Historic Masonry Churches
Published in International Journal of Architectural Heritage, 2023
Chiara Ferrero, Riccardo Berardi, Chiara Calderini, Ludovica Cambiaggi, Rita Vecchiattini
In view of the foregoing, this paper aims at developing a deeper understanding of the effects of slow-moving landslides on historic masonry churches by performing geotechnical analyses on two case studies: San Nicolò di Capodimonte complex in Camogli and San Carlo Borromeo church in Cassingheno. These case studies were selected among the buildings investigated in Ferrero et al. (2021a) due to the availability of geotechnical data, which were needed for the geotechnical modelling of the slopes where the two buildings are located. The geotechnical analyses were carried out using both the Limit Equilibrium (LE) method and the Finite Element (FE) method. The LE method was employed to assess the slope stability conditions, while the FE method was used to accurately identify the soil displacement profiles produced byslow-moving landslides. Based on the predicted values of soil displacements, the landslide-induced damage of the buildings under study was assessed and classified by damage levels through the damage criterion proposed by Son and Cording (2005).
Comparison of slope failure areas between limit equilibrium method and smoothed particle hydrodynamics
Published in European Journal of Environmental and Civil Engineering, 2022
Xuesong Chu, Liang Li, Guangming Yu, Changfeng Yuan
To determine the slope failure area, a user-defined displacement criterion is adopted in SPH algorithm. The select of displacement criterion is based on that displacement of an object can be easily monitored and analysed in practical engineering. For example, the earthquake-induced displacement of slopes was elaborately predicted using enhanced Newmark’s sliding block method. (Bandini, Biondi, Cascone, & Rampello, 2015; Deng, Tsutsumi, Kameya, & Koseki, 2010; Stamatopoulos, Mavromihalis, & Sarma, 2011) and the obtained displacement value is used to evaluate the stability conditions and failure consequence of slopes. The previous research outputs inspire the choice of displacement criterion in this study to quantify the failure consequence of slopes. If the displacement of a particle in SPH is larger than a user-defined critical value, d (e.g. d = 0.5m), the soil mass corresponding to this particle is regarded to fail and it will contribute to the total area of a slope failure. Figure 4 shows schematically the implementation procedure of the proposed approach, which consists of six steps. Details of each step are described as follows: