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Collaborating Authors
National Taiwan Ocean University
Numerical Study for Waveform Inversion as an Internal Solitary Wave over Permeable Trapezoidal Topography
Hsieh, Chih-Min (National Kaohsiung Marine University) | Cheng, Ming-Hung (National Taiwan Ocean University) | Hwang, Robert R. (National Taiwan Ocean University) | Yang, Wen-Chang (Taiwan Ocean Research Institute (TORI))
Many laboratory experiments have been extensively utilized to study the A finite volume method based Cartesian grids is adopted to solve the propagation of an ISW on a pseudo slope-shelf topography in a Reynolds averaged Navier-Stokes equations using a k-ฮต turbulence stratified two-layer fluid (Cheng et al., 2011). Although Cheng et al. model and porous media model for the study of the porous effect on the (2011) has reported the effect of the pertinent parameters on wave flow evolution as a large depression internal solitary wave propagates inversion and propagation, they only discussed the waveform evolution over a porous trapezoidal obstacle. Numerical results reveal that as the associated with amplitude and energy at specific locations using the porosity increases, the waveform inversion becomes unapparent and is video images and limited number of ultrasonic probes, rather than not found in the porosity higher than 0.2.
- Asia (0.29)
- North America > United States (0.28)
Experimental Study of Wave Impact Forces on Pervious Pipe Breakwaters
Shih, Ruey-Syan (TungnanUniversity) | Weng, Wen-Kai (National Taiwan Ocean University) | Chou, Chung-Ren (National Taiwan Ocean University)
Abstract In this study, the wave impact on highly- pervious pipe breakwaters is investigated by a physical experiment conducted in a 21-m wave flume, with a combination of pre positively placed pervious pipe obstacles and an impermeable embankment. The wave impact force on the protected coastal structures were effectively mitigated and attenuated. The process of wave impact is very complicated; involving strongly nonlinearity and transient effects, and the effect of wave impact is one of the important factors on the safety and/or destructions of coastal structures. This study addresses highly pervious dense pipe with small apertures, which can be beneficial for convection and interchange of seawater within the harbor district, and furthermore, perform effectively in wave absorption. The problems of random wave impact on the highly pervious perpendicular pipe obstacles were also investigated. Physical experiments were carried out with regular and irregular waves under various conditions. The results showed that, a pervious pipe obstacles placed vertically in the front of an impermeable embankment can effectively mitigate and attenuated the wave impact.
- North America > United States (0.28)
- Asia > Middle East (0.28)
Abstract The current phase-average wind wave model does not include the effect of porous bottom media on wave energy dissipation. The present paper incorporates the dissipation coefficient for porous bottom media in the wave action equation (WAE) of Wind Wave Model (WWM) (Hsu et al., 2005). The coefficient is obtained from the analysis mild-slope equation proposed by Rojanankmthron et al. (1989), and imitated Isobe (1987) method to add the effect of porous media in the WWM model. The accuracy of this model has been verified by comparing the experimental and numerical results. Several typical real sites were investigated using the present model.
- Energy > Oil & Gas > Upstream (0.49)
- Government > Regional Government (0.46)
- Energy > Renewable > Ocean Energy (0.36)
- Health, Safety, Environment & Sustainability > Sustainability/Social Responsibility > Sustainable development (0.36)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (0.35)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (0.30)
The Study of Geotechnical Parameters and Risk Assessment for the Supported Foundation Design of Offshore Wind Farm
Chien, Lien-Kwei (National Taiwan Ocean University) | Chiu, Shu-Yi (National Taiwan Ocean University) | Lee, Ruan-Ruey (National Taiwan Ocean University) | Wu, Chia-Chi (National Taiwan Ocean University) | Hsieh, Meng-Hsiu (Institute of Nuclear Energy Research Atomic Energy Council) | Wu, Yuan-Chieh (Institute of Nuclear Energy Research Atomic Energy Council)
Abstract The geological conditions of offshore wind farms are very important environmental risk factors for foundation design and construction. Due to the geological characteristics of the seabed in the west Taiwan have large differences so that we are lack of marine engineering equipment and construction experience and limited environmental geological data, Foundation design of offshore wind farms and marine construction will face on great risks. It could be induced and occurred the self-elevating platform vessel punch through, pile installation difficult, foundation scour damaged, submarine cable erosion and other cases in other countries. In order to simulate the reaction behavior of the offshore wind turbine supporting structure and foundation under extreme conditions such as storm and earthquakes. In this study, seismic data, drilling data and related soil data of offshore wind farm area were collected and discussed. Based on the geological conditions of Changhua offshore area, the representative soil profiles were provided. On the other hand, by use of the offshore geotechnical investigation, in-situ geotechnical testing and empirical formulas transfer. The requirement of geotechnical parameters for supporting foundation design and construction are suggestion. On the other hand, for the soft ground and spatial distribution of geological sensitive of offshore wind farm should be discussed. In this study, we will discuss and analyze the soft ground of offshore wind farm, environmental geology sensitive to the spatial distribution, seabed soil liquefaction, the stability and settlement of the foundation construction capacity and marine engineering work safety guidelines. It can be improved to reduce the risk of environmental geology in offshore wind farm and ensure the safety of marine construction in Taiwan. It can provide information to model and simulation different condition for supporting foundation design and construction.
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (0.55)
- Geology > Geological Subdiscipline > Environmental Geology (0.44)
A Study on Low-Cost Gravity Base Foundations for Offshore Wind Turbine in Taiwan
Chiang, Yun-Chih (Tzu Chu University) | Lee, Pei-Yu (National Taiwan University) | Chen, Po-Chen (National Taiwan University) | Lin, San-Shen (National Taiwan Ocean University) | Hsiao, Sung-Shan (National Taiwan Ocean University)
Abstract The growth in the capacity of offshore wind power units in Europe has leveled off in recent years. Analysis has indicated that this may be because development in the coastal waters is nearing saturation or because of risks and technical barriers. For example, the United Kingdom's Round 3 is facing wind farms with considerable depths, and this poses challenges to conventional foundation engineering methods for shallow water. This study proposes innovative solutions, which are based on the analysis of the problems faced in wind farm development in the United Kingdom and Denmark in recent years, to the current difficulties and bottlenecks of domestic and overseas offshore wind power development by integrating industrial and academic viewpoints. Such difficulties and bottlenecks include engineering and technological challenges, construction and purchasing costs, safe interactions between geological and structural features, environmental influence, conditions of the marine engineering industry, and market demand. Furthermore, this study provides alternatives for developing domestic offshore wind power. Preliminary results indicated that an optimal solution that can enable Taiwan to develop offshore wind power while promoting the domestic marine engineering industry involves using a caisson gravity foundation paired with superstructures and turbines preassembled onshore, transported by towing, and installed by submergence.
- Overview > Innovation (0.48)
- Research Report (0.46)
Monitoring of Yan Liao Beach Nourishment in Northeast Coast of Taiwan
Fang, Hui-Ming (National Taiwan Ocean University) | Hsiao, Sung-Shan (National Taiwan Ocean University) | Oh, Erwin (Griffith University) | Liang, Zuo-Dong (Griffith University)
Abstract Yan-Liao beach in Northeast Coast National Scenic Area is a hot spot. In recent years, the visitors pay much attention to the issues of beach erosion and beach restoration. The goal of this study is to assess the effects of Yan-Liao beach nourishment after storm damage of Typhoon KROSA (2007). The selection of shore protection method was based on the consideration of effective sand dune protection, beach recreation function and water quality protection. To achieve the effective disaster prevention function, associated seaward dune nourishment and nourishment of subaerial beach were performed at Yan-Liao beach. According to the monitoring of beach nourishment project, the beach profile and beach width is steadily being restored. It is demonstrated that this kind of beach nourishment has a valuable reference for shore protection.
- North America > United States (0.46)
- Asia > Taiwan (0.43)
Adaptive Modeling for Typhoon Wave Predictions around Taiwan
Hou, Tien-Hung (National Cheng Kung University) | Hsu, Tai-Wen (National Taiwan Ocean University) | Tsai, Chia-Cheng (National Kaohsiung Marine University)
Abstract In this paper, we apply a quadtree-adaptive scheme for hindcasting wave spectra during Typhoon Soulik. In the simulation, the quadtree grid system can be adapted to the vicinity of the typhoon and some prescribed regions, where require higher resolutions. In other words, the quadtree grid system can move with the typhoon and then reduce the number of grids for computation. In our simulations we consider a square computational domain of 3,200*3,200 square kilometers with its center at latitude 26.5ยฐN and longitude 126.5ยฐ W, and use the combined wind fields of the NOAA operational wave model and the model of Taiwan's Central Weather Bureau. The required computing time for the adaptive scheme is about 10 times shorter compared with that of the traditional model. In an adaptive simulation with the highest spatial resolution of 25 kilometers and temporal resolution of 1 hour, the required computing time is only 0.67 hours for the 7-days typhoon event. At the same time, the difference between the predicted significant wave heights and the buoy measurements is accredited. These results indicate that the proposed adaptive scheme can significantly save the time required for a specific simulation and is very convenient for an operational forecasting.
Numerical Simulation of Morphological Changes around Offshore Wind Turbine Foundations in Taiwan Western Coast
Chiang, Yun-Chih (Tzu Chu University) | Hsiao, Sung-Shan (National Taiwan Ocean University) | Fang, Hui-Ming (National Taiwan Ocean University) | Wang, Hsing-Yu (National Taiwan Ocean University) | Lin, Ming-Chung (National Taiwan Ocean University)
Abstract The development for renewable energy is highly valued, and offshore wind energy is one of the few kinds of sustainable energy which can be operated reliably and harvested efficiently. The feasibility evaluation of the offshore turbines should include an assessment of the possible long-term morphological evolution, and an assessment of the local erosion caused by the turbine foundations. In this paper, a numerical model is presented for the simulations of the morphological changes in large coastal area and local seabed evolutions near turbine foundation. The target wind farm is located at the Fang-Yuan coast, Chang-hua County in Taiwan western Coast. We investigated the influence of an offshore wind farm on the large-scale morphological evolution of the seabed with the jacket type foundation. The results show that there is slight influence for large coastal area around the offshore wind turbine foundation.
A New Model of Pore Pressure Generation for Seabed Soils Under Typhoon Wave Loading
Chien, Lien-Kwei (National Taiwan Ocean University) | Tseng, Wen-Chien (National Taiwan Ocean University) | Chiu, Shu-Yi (National Taiwan Ocean University) | Chang, Chih-Hsin (National Science and Technology Center for Disaster Reduction)
Abstract With climate change in recent years caused the occurred frequency increasing of extremely waves. Due to sea level rise and the typhoon disasters, it could be caused the pore pressure of seabed may be sustained a build-up state below the coastal structures, and occurring and increasing the risk of the seabed liquefaction. Most of the past related researches followed the earthquake relevant theory to evaluate the dynamic characteristic of cyclic wave loading, including wave induced the single external stress or internal stress, number of cycles in seabed, and pore pressure generation model for earthquake mechanism. Therefore, this study used experimental mechanics and theoretical model to simulate liquefaction behavior under typhoon wave loading with case study of "Zone A" of Kaohsiung Harbor Intercontinental Container Center at second stage project. From the related cyclic triaxial test results, this study proposed an pore pressure generation model for seabed under long-term wave loading by the hyperbolic sine function, and suggest a testing parameter to predict the curve of pore pressure under different test conditions as Tp=0.005, 0.05 and 0.5. The model can be applied in assessment of typhoon wave induced seabed liquefaction potential. The maximum possible liquefied depth is about 6.6m when Tc =1200s in this study area, and provide the well marine geotechnical practical application for seabed stability.
- North America > United States > California (0.28)
- Asia > Taiwan > Takao > Kaohsiung (0.26)
- Overview > Innovation (0.50)
- Research Report > New Finding (0.35)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (0.97)
A Case Study of the Performance-based Seismic Design for Sheet Pile Wharf in Taiwan
Ku, Cheng-Yu (National Taiwan Ocean University) | Chang, Ching-Chung (National Taiwan Ocean University) | Tseng, Wei-Fan (National Taiwan Ocean University) | Lai, Jui-Ying (Ministry of Transportation and Communications)
Abstract The study presents the performance-based seismic design case studies for the sheet pile wharf. Three different analysis methods including the simplified analysis, the simplified dynamic analysis, and the dynamic analysis were adopted for evaluating the performance of the sheet pile wharf under different levels of earthquake motions. The process of the performance-based seismic design for the sheet pile wharf was established. In addition, the feasibility of the performance-based seismic design for the sheet pile wharf was investigated. Results obtained demonstrate that the dynamic characteristic of backfill materials plays a crucial role for designing the sheet pile wharf.
- North America > United States (1.00)
- Asia (0.85)