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ABSTRACT This paper first reviews (1) the storm surge and wave disasters in the coastal and port areas of Osaka Bay and Tokyo Bay in Japan in 2018 and 2019, respectively and (2) two intensity levels of typhoons for coastal defense design and evacuation planning. Then, the paper summarizes their technical issues, such as, the radius of maximum wind speed in worst-case storm surge and wave-overtopping flood simulations. Finally, the paper presents climate change related issues, such as: (1) past mean sea level, typhoon, wave, and storm surge trends, and (2) future climate change adaptation. INTRODUCTION Fig. 1 shows that Japan has many cities of more than million people on low plains that extend from the coast of very enclosed bays. These bays are several tens of kilometers from the mouth to the head and have maximum depths of a few tens of meters. They are usually calm but meet storm surges and high waves during typhoon events. In addition, ground-water pumping has caused some parts of the land to sink below the mean monthly-highest water level (hereinafter, HWL) and increased the risk of flooding. The ports on the coast play a core role in international shipping and the country's economy. Two major storm surge disasters occurred in the 1950s. The 1953 Typhoon Tess crossed the mouth of Ise Bay and triggered storm surge flooding along the southern and eastern coast. This event led to the enactment of the 1956 Coast Act, which requests each prefectural governor to protect coastal areas from tsunamis, storm surges, and high waves. The 1959 Typhoon Vera caused a landfall on Honshu Island (central pressure: 929 hPa) and passed by Ise Bay (940 hPa), generated a storm surge in the bay, recorded 3.5 m at Nagoya Port, causing the collapse of the coastal dike and flooding over the area of 30 km inlands that lasted for 120 days, eventually claiming 5,000 lives. The flood carried much lauan logs from lumberyards in the port and destroyed many buildings. The event prompted the national and local governments to start building massive coastal defense in the 1960s on the coast of Tokyo Bay, Ise Bay, and Osaka Bay for the storm surge of the Vera-class design typhoon (Kawai, 2019).
ABSTRACT As the behavior of tsunami debris in an enclosed sea area is dominated by time-dependent external forces such as tide, wind, and freshwater inflow, the timing of discharge of tsunami debris is important for the analysis of drift destination. Discharge and drifting processes were modeled considering inundation to understand variations in the drifting behavior and map hazardous areas where secondary disasters induced by tsunami debris under different meteorological conditions in Osaka Bay can occur. Results show that the hazardous area prone to fire on the sea surface substantially depended on wind direction and freshwater flow rate. INTRODUCTION The Great East Japan Earthquake that occurred in 2011 caused enormous damage. The massive tsunami generated by the earthquake inundated an area of about 560 km (Geospatial Information Authority of Japan, 2011) and washed many ships, containers, vehicles, and other debris ashore. Hiroi et al. (2012) reported that tsunami debris and oil spilled from damaged oil complexes caused fires on the sea surface, and the fire expanded to the affected area in Kesennuma Bay, Miyagi Prefecture. In most other ports, tsunami debris caused secondary disasters such as blockage of shipping routes, leading to shortages of goods. Natural disaster sometimes causes damages to industries, known as natural-hazard-triggered technological (Natech) accidents. Osaka, one of the largest cities in Japan, is expected to be attacked by a tsunami generated by the probable Nankai Trough earthquake with a 70 to 80% chance within the next 30 years. A five-meter tsunami is predicted in the coastal area of Osaka Bay, inundating an area of about 50 km. Large ports with many wharves and various industries that have oil tanks and flammable-product storages operate in the coastal area. Secondary disasters such as the blockage of shipping routes caused by sunk vehicles and other debris and fires may affect the facilities soon after a tsunami. Natech will damage industries and endanger the continuity of businesses.
Zhang, Song (School of Transportation and Logistics Engineering, Wuhan University of Technology, Wuhan) | Wu, Qing (School of Transportation and Logistics Engineering, Wuhan University of Technology, Wuhan) | Liu, Jialun (Intelligent Transportation Systems Research Center, Wuhan University of Technology, Wuhan / National Engineering Research Center for Water Transport Safety, Wuhan) | He, Yangying (School of Navigation, Wuhan University of Technology, Wuhan) | Yang, Zhen (Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, Guangdong)
ABSTRACT Tugs have a simple hull form and good maneuverability. This paper works on the hydrodynamic performance of an ASD harbor tug with a skeg and bilge keels. Virtual oblique towing tests (OTT) and circular motion tests (CMT) are conducted via the Reynolds-Averaged Navier-Stokes (RANS) method, to investigate the resistance and moment characteristics. The obtained low-speed body forces and moments of the harbor tug hull provide a basis for the establishment of the maneuverability model and reference for operators to the hydrodynamic performance of the ship. INTRODUCTION In the busy harbor areas, tugs are widely used to execute escort, rescue, berthing-assistant and other missions with low-speed steering. The operational demands of the tug inspire the study of maneuverability in terms of safety, effectiveness and operability. It is delicate and indispensable to study the hydrodynamic performance of the tug in certain motions. Traditionally, experimental and empirical methods are utilized to study the hydrodynamic forces and maneuverability of a ship. Oltmann (Oltmann and Sharma 1984) studied the hydrodynamic characteristics of a single crew tanker and a twin-propeller twin-rudder container ship based on slow-speed constraint model tests, and predicted the forward and backward motion of the ships. The work of Kho King Koh (Koh and Yasukawa 2012), Fitriadhy and Yasukawa (Fitriadhy, Yasukawa et al. 2015) on the tug-towing system and tug-pusher system enables the prediction of the inland tug assistance system. Yoshimura (Yoshimura 1988), Kijima (Kijima, Katsuno et al. 1990), and other scholars summarized universal empirical methods to predict ship maneuverability under different circumstances. CFD methods are now widely used to study the hydrodynamic performance and flow characteristics of the ship. Zhang (Zhang, Liu et al. 2019). Chen (Chen, Zou et al. 2017) carried out CMT tests to study the forces and moments of the Esso Osaka model with large drift angles. Based on virtual static and dynamic constraint model tests, Benedetto (Piaggio, Viviani et al. 2018, Piaggio, Villa et al. 2020, Piaggio, Villa et al. 2020) investigated the hydrodynamic forces and moments of an escort tug at slow- and high-speed conditions.
Cai, Boao (China Ship Development and Design Center / School of Naval Architecture, Ocean and Energy Power Engineering, Wuhan University of Technology / Key Laboratory of High Performance Ship Technology (Wuhan University of Technology), Ministry of Education) | Xu, Qing (China Ship Development and Design Center / School of Naval Architecture, Ocean and Energy Power Engineering, Wuhan University of Technology / Key Laboratory of High Performance Ship Technology (Wuhan University of Technology), Ministry of Education) | Qiu, Liaoyuan (China Ship Development and Design Center) | Tian, Binbin (China Ship Development and Design Center) | Mao, Xiaofei (School of Naval Architecture, Ocean and Energy Power Engineering, Wuhan University of Technology / Key Laboratory of High Performance Ship Technology (Wuhan University of Technology), Ministry of Education) | Qin, Jiangtao (School of Naval Architecture, Ocean and Energy Power Engineering, Wuhan University of Technology / Key Laboratory of High Performance Ship Technology (Wuhan University of Technology), Ministry of Education) | Chai, Wei (School of Naval Architecture, Ocean and Energy Power Engineering, Wuhan University of Technology / Key Laboratory of High Performance Ship Technology (Wuhan University of Technology), Ministry of Education)
ABSTRACT In numerical research of ship self-propulsion, the body force method is widely used to save the computational resources. In this work, the body force method is introduced to simulate the self-propulsion of the ship in shallow water. Specifically, the KVLCC2 model and the propeller model are taken as research objects. The results of the body force method show good agreement with the discretized propeller method in different water depths. In addition, water depth influences the thrust deduction fraction and the wake fraction significantly. The calculation results can provide a basis for the optimization of ship with low speed and large block coefficient as well as for the propeller optimization in shallow water. INTRODUCTION Research of ship self-propulsion performance is of great significance to the design of ships and propellers. Compared with model tests, computational fluid dynamics (CFD) can not only reduce cost, but also provide details of the flow field which are difficult to capture in the tests. For numerical simulation, the discretized propeller method and the body force method are widely used (Lübke, 2005; Hough and Ordway, 1964). In order to capture the complex transient flow around a rotating propeller, the discretized propeller method requires a great number of grids and a small-time step. When the details of flow field are not the focus, the body force method can be applied as an effective alternative method to simulate self-propulsion. In this method, the real propeller is replaced by a virtual disk which can generate force and torque just like the propeller, therefore, the computational efficiency can be greatly improved (ADAPCO, 2021). Based on the methods of obtaining the source term of body force, the body force method can be divided into the descriptive body force method and the iterative body force method (Moctar, 2001; Kawamura et al., 1997). In the descriptive body force method, the thrust and the torque of the propeller are discretized in the virtual disk with a specific distribution. The body force model proposed by Hough and Ordway (H-O) (Hough and Ordway, 1964) is the most widely used model, and quite accurate results can be obtained even without considering the torque (Wu et al., 2013). However, if the torque is not considered in the uniformly distributed body force model, it may cause errors (Lv et al., 2013). Recently, Lee et al. (2021) employed the descriptive body force method to predict the self-propulsion performance of a ship in regular waves, and the calculation time has been greatly shortened. Different from the descriptive body force method, the iterative body force method has better performance in capturing the details of flow field (Choi et al., 2010). In this method, the propeller load calculated by potential flow method is converted into a body force distribution, which is then applied to the Reynolds-averaged Navier-Stokes (RANS) solver, and the flow fields of the propeller and the hull are iterated until convergence (Simonsen, 2005; Vaz and Bosschers, 2006). In order to avoid errors caused by the BEM solver in the iterative body force method, Qin (2014) calculated the flow fields of the propeller in the RANS solver. Recently, a new iterative body force method without nesting iteration has been put forward and reduces the time of calculation (Guo et al., 2020). Feng et al. (2020) presented a modified Osaka University Method (OUM) coupled with blade element momentum theory (BEMT). Based on this method, the full-scale KCS free running simulation is further studied (Yu et al., 2021). Furthermore, the body force method is widely used in the field of ocean engineering, such as tidal turbines and water turbines (Turnock et al., 2011; Dominguez et al., 2016).
The enhanced unified theory (EUT) has been used as a core theory in the integrated system developed at the Research Initiative on Oceangoing Ships (RIOS) of Osaka University for predicting the propulsion and seakeeping performance of a ship in actual seas. In this study, the EUT is modified by adopting partially the solution method in the rational strip theory of Ogilvie and Tuck as a particular solution in the inner problem, thereby a forward-speed effect in the convection term of the free-surface condition is incorporated in the inner solution. This forward-speed effect is analytically shown to contribute only to the cross-coupling radiation forces. Some other forward-speed and 3D effects important in a low-frequency range are also included in the homogeneous component of the inner solution through matching with the outer solution in a similar manner to the unified theory of Newman. Numerical computations are implemented for a slender modified Wigley model and the RIOS bulk carrier model. Good agreement is confirmed in a comparison with experimental data for the cross-coupling added mass and damping coefficients between heave and pitch and also for the resulting ship motions, particularly in heave near the resonant frequency. The added resistance around the motion-resonant wavelength is found to be improved but sensitive to a slight change in heave and pitch motions. Thus, it is stressed that accurate prediction of the ship motions and resultant Kochin function is critical for more accurate prediction of the added resistance in waves. Introduction Although the design of the ship hull form has been based mainly on the propulsion performance in still water, recently, prediction and onboard data analysis for the propulsion and seakeeping performance of a ship in actual irregular waves have been attracting attention of the researchers (Orihara & Tsujimoto 2018; Minoura et al. 2019). In fact, real ships navigate mostly in rough seas, and thus, the so-called short-term and long-term predictions of ship response in actual seas must be made to guarantee the performance and safety of a ship. This trend to study the seakeeping performance of a ship is partly because the Energy Efficiency Design Index regulation was introduced by International Maritime Organization (IMO) to reduce greenhouse gas emission from the ships in operation. Thus, it becomes important to predict with sufficient accuracy the wave-induced ship motions, the added resistance, and the resultant speed loss of a ship in irregular waves represented by a directional wave spectrum (Kashiwagi 2009; Kim et al. 2017) even in the initial stage of ship design, necessitating computations for various profiles of a candidate ship.
Abstract A buckling risk of oil storage tank under tsunami inundation was numerically investigated with Fluid–Structure Interaction (FSI) analysis. The fluid region of two–phase flow in tsunami was solved with a finite volume method solver based on VOF method and the solid region inside a storage tank model was solved with a finite element solver, and the field variables between the different regions were successfully exchanged without vast numerical cost. The developed simulation was applied to the problem for estimating tsunami and storage tank motion and the dependency of tank structural properties on buckling risk was investigated. INTRODUCTION The Great East Japan Earthquake at 2011 caused heavy damages to Japan. When the earthquake occurred, a large tsunami was generated at Pacific Ocean, and the tsunami wave reached at Tohoku area in Japan. The tsunami inundation was widely observed at Tohoku area, and many peoples were injured and missed in this area. This tsunami wave only caused temporally flood disaster but triggered tsunami fire disaster due to oil spill. At the Kesennuma bay area in Miyagi prefecture, there were 23 oil storage tanks before the earthquake, then 22 tanks were broken and massive amounts of oil were flow out from the damaged tanks and wide fire disaster was caused at the tsunami inundation area (Zama, 2012). From this earthquake, tsunami fire disaster due to oil spill became to be known as a new risk when a large earthquake happens at countries with chemical complexes at bay area. Japan is located at the position in which the probability of earthquake occurrence is very high. The Nankai Trough Earthquake assumes to be occurred in a few decades, many risk assessments for this earthquake are conducted based on numerical estimation. Tsunami simulation becomes a popular method for estimating inundation level and the detailed review for general tsunami calculation is not shown here.
Kanehira, Taiga (Hiroshima University) | Gabl, Roman (The University of Edinburgh) | Jordan, Laura-beth (The University of Edinburgh) | Davey, Thomas (The University of Edinburgh) | Nakashima, Takuji (Hiroshima University) | Taniguchi, Naokazu (Hiroshima University) | Ingram, David (The University of Edinburgh) | Mutsuda, Hidemi (Hiroshima University)
Abstract The absorption of waves in a circular wave basin using segment-type wave makers is challenging due to the curvature, which may generate undesirable imperfections in long-crested regular wave fields close to the absorbing side of the FloWave circular wave tank with a diameter of 25 m and a water depth of 2 m. A velocity component perpendicular to the wave direction could be found numerically and experimentally, which is a key tool to understand and optimise the active wave absorption in a circular wave basin. Conducting long-crested regular wave simulation using the SPH model based on Kanehira et al. (2019), the location of the hot-spots (constructive and destructive interference locations of waves) could be identified in the vicinity of absorption paddles as well as velocity components perpendicular to wave propagation direction, which are the potential cause of or caused by the hot-spots. Specific experimental investigations were conducted based on numerical results to validate the numerical model based on free surface elevation and local velocities. It could be shown that the location and strength of the hot-spots vary with wave frequencies and steepnesses as well as the connection between hot-spots and the velocity components perpendicular to wave direction. This combined approach has a high potential to provide insight into the absorption mechanism in a circular basin and helps to further improve the wave conditions in future. INTRODUCTION In the context of the development of o shore structures such as vessels and ocean energy devices (OEDs), laboratory experiments can provide insight into how sea states affect the dynamics and the durability of structures developed as well as providing critical validation data for the numerical simulations. Therefore, a variety of wave tanks have been developed and utilised in ocean and coastal engineering. In particular, multi-directional wave basins, incorporating multiple segment-type wave makers, are commonly used for OED model testing due to the demand to exploit renewable energy in the open-ocean (Caglayan et al., 2019, Draycott et al., 2019). A number of multidirectional wave basins have been developed such as the circular AMOEBA basin at Osaka University (Minoura et al., 2009), deep-sea basin at the National Maritime Research Institute, Japan (Maeda et al., 2004), and the FloWave Ocean Energy Research Facility circular wave and current basin at the University of Edinburgh (Ingram et al., 2014). These circular wave basins can generate realistic short-crested sea states as well as long-crested regular/irregular waves coming from any direction including combination to achieve realistic complex sea states. In particular, the correct generation and absorption system in a long-crested regular wave condition are important, as realistic waves are generated by the summation of regular wave components with different wave frequencies and directions (e.g. single/double-summation methods).
Abstract Computations were done to predict the motions and forces of KVLCC2 of 3.2m model ship with normal rudder and with RBFS. 2DOF (heave and pitch) motions and forces are compared with EFD data with 3.2m model at Froude number of 0.142 for various head wave conditions. The experiment was conducted in the towing tank of Osaka University with fully loaded condition at model speed of 0.795 m/s. In numerical prediction, CFD Ship-IOWA V4.5 was used. RBFS does not have any adverse condition and can reduce power required in some waves. CFD predicted well and had good agreement with EFD. INTRODUCTION Maritime shipping is the world's most carbon-efficient form of transporting goods - far more efficient than road or air transport. The industry seeks to further improve the fuel efficiency and carbon footprint of its vessels. Shipping also contributes to climate change through emissions of Black Carbon, tiny black particles, produced by combustion of marine fuel. The highest amounts of black carbon particles are produced by ships burning heavy fuel oil. In recent years, discussions at the International Maritime Organization (IMO) have resulted in the development of an Energy Efficiency Design Index (EEDI) that led to the adoption in 2011 of legally-binding energy efficiency standards applicable to newly-built ships. The standards apply to ships built in 2013 and later and require all future ships to meet increasingly stringent fuel economy standards over time. As mentioned above, increased environmental awareness, huge carbon dioxide emission reduction and energy crises make energy saving devices (ESDs) aiming at improving ship energy efficiency to pay high attention. Most of these devices are used to improve propeller efficiency by recovering as much as possible of the rotational energy in the flow from the propeller. Several of them contain modifications to the rudder or propeller. Depending on types of vessel and working environment, different power saving methods can be utilized to optimize water velocity distribution to the propeller and to lower the slipstream losses owing to swirl in the outflow of the propeller. A combination of rudder bulb and rudder fins (RBFS) is one of these hydrodynamically based energy saving devices. The rudder bulb is an ESD installed on the leading edge of the rudder blade at the center position of the propeller shaft. It can cut down the space of low pressure at the axis after the propeller and strengthen the rectification of rudder and decrease the circumferential velocity of propeller. It can also make the propeller wake field uniform and has the benefit of the cavitation performance of propeller. The rudder fin is the thrust fin fitted on both sides of the rudder and has an opposite installation angle to the direction of the inflow. While rotating the propeller, the rudder fins produce the additional thrust from the interaction between the fin blade and the wake flow from the propeller. Crist (2009) stated that these RBFS can be applied in both new and retrofit tanker, bulk carrier, container and Ro-Ro ships and the estimated payback time is medium (4 to 15 years).
The INPEX-led Ichthys LNG project in Australia was recognized by the 2021 International Petroleum Technology Conference (IPTC) Excellence in Project Integration Award, which highlights projects with budgets of at least $500 million that have demonstrated distinction throughout the entire exploration and production value chain. The announcement was made during the 2021 IPTC Opening Ceremony on 23 March. The award is given to a project that adds value to the industry and exemplified strong teamwork, solid geoscience knowledge, reservoir and production engineering acumen, determined and watchful construction, and outstanding facilities engineering practices. Ichthys is ranked among the most significant oil and gas projects in the world. A joint venture between INPEX group companies (the operator), major partner Total, and the Australian subsidiaries of CPC Corporation Taiwan, Tokyo Gas, Osaka Gas, Kansai Electric Power, JERA, and Toho Gas, Ichthys LNG is expected to produce 8.9 mtpa of LNG and 1.65 mtpa of LPG, along with more than 100,000 bbl of condensate per day at peak.
A trio of finalists is in contention for the 2021 International Petroleum Technology Conference (IPTC) Excellence in Project Integration Award highlighting projects with budgets of at least $500 million that have demonstrated distinction throughout the entire exploration and production value chain. The IPTC Excellence in Project Integration Award is given to a project that adds value to the industry and exemplified strong teamwork, solid geoscience knowledge, reservoir and production engineering acumen, determined and watchful construction, and outstanding facilities engineering practices. The three nominees are Total's Culzean development in the UK North Sea, the INPEX-led Ichthys LNG project in Australia, and Saudi Aramco's Khurais Arab Light Increment in Saudi Arabia. The project included a newbuild drill rig, a three-platform processing complex, a newbuild FSO and over 60 km of large-bore gas export pipeline, and was delivered safely, ahead of schedule as well as under budget. Ichthys is ranked among the most significant oil and gas projects in the world. A joint venture between INPEX group companies (the operator), major partner Total, and the Australian subsidiaries of CPC Corporation Taiwan, Tokyo Gas, Osaka Gas, Kansai Electric Power, JERA and Toho Gas, Ichthys LNG is expected to produce 8.9 mtpa of LNG and 1.65 mtpa of LPG, along with more than 100,000 bbl of condensate per day at peak.