Marcio Yamamoto, Tomo Fujiwara, J. Yamamoto, Sotaro Masanobu
One key technology for Deep-Sea Mining is the riser system. The riser is already a field-proven technology in the Petroleum Industry. However, several differences exist between a petroleum production riser and a riser for Deep-Sea Mining, mainly related to the internal flow. The ore-slurry has a larger density than the hydrocarbons and shall be pumped with a much higher flowrate. The current software tools for riser’s dynamic analysis may include the internal fluid hydrostatic pressure and the centrifugal and Coriolis forces imposed by the bent pipe’s internal flow. However, the internal pressure drop is not calculated. The internal pressure alters the pipe’s effective tension and can alter the pipe’s bending moment changing its mechanical behavior. This article describes a computational script’s development to run embedded in a commercial software for riser’s dynamic analysis. Our script calculates the internal viscous pressure drop along with the jumper. This pressure is then converted into wall axial tension (buckling) and imposed on each node of the jumper’s numerical model. Each simulation case was calculated twice with and without the internal flow viscous pressure drop. The comparison with experimental data revealed that the jumper’s average position has a good agreement among all cases. However, the amplitude caused by the top oscillation showed some discrepancies. Experimental data has the highest amplitude in the horizontal direction, while the simulation without viscous pressure calculation had the smallest. The simulation with our embedded script had intermediary amplitude in the horizontal direction. The vertical direction amplitudes have the same behavior for all cases, but the experimental data showed the highest amplitude.
{"title":"Numerical Simulation of a Jumper Conveying Slurry for Deep-Sea Mining","authors":"Marcio Yamamoto, Tomo Fujiwara, J. Yamamoto, Sotaro Masanobu","doi":"10.1115/omae2021-62356","DOIUrl":"https://doi.org/10.1115/omae2021-62356","url":null,"abstract":"\u0000 One key technology for Deep-Sea Mining is the riser system. The riser is already a field-proven technology in the Petroleum Industry. However, several differences exist between a petroleum production riser and a riser for Deep-Sea Mining, mainly related to the internal flow. The ore-slurry has a larger density than the hydrocarbons and shall be pumped with a much higher flowrate.\u0000 The current software tools for riser’s dynamic analysis may include the internal fluid hydrostatic pressure and the centrifugal and Coriolis forces imposed by the bent pipe’s internal flow. However, the internal pressure drop is not calculated. The internal pressure alters the pipe’s effective tension and can alter the pipe’s bending moment changing its mechanical behavior.\u0000 This article describes a computational script’s development to run embedded in a commercial software for riser’s dynamic analysis. Our script calculates the internal viscous pressure drop along with the jumper. This pressure is then converted into wall axial tension (buckling) and imposed on each node of the jumper’s numerical model.\u0000 Each simulation case was calculated twice with and without the internal flow viscous pressure drop. The comparison with experimental data revealed that the jumper’s average position has a good agreement among all cases. However, the amplitude caused by the top oscillation showed some discrepancies. Experimental data has the highest amplitude in the horizontal direction, while the simulation without viscous pressure calculation had the smallest. The simulation with our embedded script had intermediary amplitude in the horizontal direction. The vertical direction amplitudes have the same behavior for all cases, but the experimental data showed the highest amplitude.","PeriodicalId":269406,"journal":{"name":"Volume 5: Ocean Space Utilization","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126662303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wave energy converters (WECs) have been extensively researched. The behaviour of the oscillating water column (OWC) in OWC WECs is extremely complex due to the interaction of waves, air, and turbines. Several problems must be overcome before such WECs can be put to practical use. One problem is that the effect of the difference in scale between a small-scale experimental model and a full-scale model is unclear. In this study, several OWC models with different scales and geometries were used in forced oscillation tests. The wave tank was 7.0 m wide, 24.0 m long, and 1.0 m deep. In the static water experiment, we measured the air pressure and water surface fluctuations in an air chamber. For the experiments, models with a box shape with an open bottom, a manifold shape with an open bottom, and a box shape with a front opening, respectively, were fabricated. Furthermore, 1/1, 1/2, and 1/4 scale models were fabricated for each shape to investigate the effects of scale and shape on the air chamber characteristics. Numerical calculations were carried out by applying linear potential theory and the results were compared with the experimental values. The results confirmed that the air chamber shape and scale affect the air pressure fluctuation and water surface fluctuation inside the OWC system.
{"title":"Scale and Configuration Effects of an Airchamber on PTO of Oscillating Water Column Type Wave Energy Converters","authors":"T. Ikoma, Shota Hirai, Y. Aida, K. Masuda","doi":"10.1115/omae2021-62173","DOIUrl":"https://doi.org/10.1115/omae2021-62173","url":null,"abstract":"\u0000 Wave energy converters (WECs) have been extensively researched. The behaviour of the oscillating water column (OWC) in OWC WECs is extremely complex due to the interaction of waves, air, and turbines. Several problems must be overcome before such WECs can be put to practical use. One problem is that the effect of the difference in scale between a small-scale experimental model and a full-scale model is unclear. In this study, several OWC models with different scales and geometries were used in forced oscillation tests. The wave tank was 7.0 m wide, 24.0 m long, and 1.0 m deep. In the static water experiment, we measured the air pressure and water surface fluctuations in an air chamber. For the experiments, models with a box shape with an open bottom, a manifold shape with an open bottom, and a box shape with a front opening, respectively, were fabricated. Furthermore, 1/1, 1/2, and 1/4 scale models were fabricated for each shape to investigate the effects of scale and shape on the air chamber characteristics. Numerical calculations were carried out by applying linear potential theory and the results were compared with the experimental values. The results confirmed that the air chamber shape and scale affect the air pressure fluctuation and water surface fluctuation inside the OWC system.","PeriodicalId":269406,"journal":{"name":"Volume 5: Ocean Space Utilization","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127795110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper develops a practical approach based on Python that couples the hydrodynamic analysis with the structural analysis, in order to solve the hydroelastic problem of Very Large Floating Structure (VLFS). The hydrodynamic analysis is carried out by solving linear 3D diffraction and radiation problems in the frequency domain, while the structural analysis is performed by a time-domain nonlinear finite element model. The coupling is realized by a generalized mode expansion method where the elastic deformation of the VLFS is regarded as extended radiation mode in the water. We consider a pontoon-type floating plate in regular waves. Analytical mode shape functions are used for representing the VLFS elastic deformations. The Mindlin plate theory is used for the finite element model. Convergence study of structure mode shape numbers, hydrodynamic model mesh and finite element model mesh is carefully carried out. Good agreements of the vertical displacement of the floating plate are found compared with experimental data and numerical results in the literature. Our simulation results show that the dynamic response of the VLFS is significantly influenced with consideration of its elastic deformation in the waves, and we see the influence is more pronounced in relatively shorter waves. The proposed approach is shown promising for hydroelastic analysis for more complex VLFS in realistic ocean seastates.
{"title":"A Coupled Frequency and Time Domain Approach for Hydroelastic Analysis of Very Large Floating Structure","authors":"Dengshuo Chen, Xingya Feng, Chao Hou, Jian-Fei Chen","doi":"10.1115/omae2021-62983","DOIUrl":"https://doi.org/10.1115/omae2021-62983","url":null,"abstract":"This paper develops a practical approach based on Python that couples the hydrodynamic analysis with the structural analysis, in order to solve the hydroelastic problem of Very Large Floating Structure (VLFS). The hydrodynamic analysis is carried out by solving linear 3D diffraction and radiation problems in the frequency domain, while the structural analysis is performed by a time-domain nonlinear finite element model. The coupling is realized by a generalized mode expansion method where the elastic deformation of the VLFS is regarded as extended radiation mode in the water. We consider a pontoon-type floating plate in regular waves. Analytical mode shape functions are used for representing the VLFS elastic deformations. The Mindlin plate theory is used for the finite element model. Convergence study of structure mode shape numbers, hydrodynamic model mesh and finite element model mesh is carefully carried out. Good agreements of the vertical displacement of the floating plate are found compared with experimental data and numerical results in the literature. Our simulation results show that the dynamic response of the VLFS is significantly influenced with consideration of its elastic deformation in the waves, and we see the influence is more pronounced in relatively shorter waves. The proposed approach is shown promising for hydroelastic analysis for more complex VLFS in realistic ocean seastates.","PeriodicalId":269406,"journal":{"name":"Volume 5: Ocean Space Utilization","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130143262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sayaka Suda, A. S. Kularathna, S. Tabeta, K. Takagi
Local fishery unions have a significant authority over the use of marine space in Japan. Building consensus with them on marine space use have been identified as significant barriers to development of offshore wind projects. Creating non-monetary benefits and adding value to the local fisheries is a required strategy for getting fisheries consensus for future offshore wind projects. Previous studies have proposed and evaluated several such benefit creation options. However, there still remains uncertainty of the effectiveness of such benefit creation options. This study aims to compare the local residents’ and fisheries’ preference of the benefit creation options by using questionnaire surveys and stakeholder interviews in three areas. Those valid responses have been selected for the preference analysis by using the DS-AHP multi criteria decision making model. This study shows that project location and other regional differences are significant factors of general residents’ attitudes of offshore wind projects. On the other hand, fishers, the most important stakeholders, preferred added values related to their fishing industry. Additionally, regional location and fishing method is found to have an impact on their preference.
{"title":"A Case Study on Consensus Building With Fisheries for Offshore Wind-Power Generation in Japan","authors":"Sayaka Suda, A. S. Kularathna, S. Tabeta, K. Takagi","doi":"10.1115/omae2021-62588","DOIUrl":"https://doi.org/10.1115/omae2021-62588","url":null,"abstract":"\u0000 Local fishery unions have a significant authority over the use of marine space in Japan. Building consensus with them on marine space use have been identified as significant barriers to development of offshore wind projects. Creating non-monetary benefits and adding value to the local fisheries is a required strategy for getting fisheries consensus for future offshore wind projects. Previous studies have proposed and evaluated several such benefit creation options. However, there still remains uncertainty of the effectiveness of such benefit creation options. This study aims to compare the local residents’ and fisheries’ preference of the benefit creation options by using questionnaire surveys and stakeholder interviews in three areas. Those valid responses have been selected for the preference analysis by using the DS-AHP multi criteria decision making model. This study shows that project location and other regional differences are significant factors of general residents’ attitudes of offshore wind projects. On the other hand, fishers, the most important stakeholders, preferred added values related to their fishing industry. Additionally, regional location and fishing method is found to have an impact on their preference.","PeriodicalId":269406,"journal":{"name":"Volume 5: Ocean Space Utilization","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130748992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The front matter for this proceedings is available by clicking on the PDF icon.
通过点击PDF图标可获得本次会议的主题。
{"title":"OMAE2021 Front Matter","authors":"","doi":"10.1115/omae2021-fm5","DOIUrl":"https://doi.org/10.1115/omae2021-fm5","url":null,"abstract":"\u0000 The front matter for this proceedings is available by clicking on the PDF icon.","PeriodicalId":269406,"journal":{"name":"Volume 5: Ocean Space Utilization","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114705436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Yamamoto, Marcio Yamamoto, Y. Nakajima, Satoru Takano, S. Kanada, Masao Ono, Kazuhisa Otsubo
Methane hydrate has been found below the seafloor in the Exclusive Economic Zone (EEZ) of Japan in a large amount. During the methane hydrate transportation, it is concerned that the riser pipe or the flowline can be plugged by the hydrate reformation and the freezing of seawater. The degradation and reformation kinetics of methane hydrate are mainly controlled by temperature, pressure, and methane concentration in the system; however, it is difficult to predict these factors in the multiphase flow because they are affected by fluid dynamics and heat transfer. To obtain the experimental data of the degradation kinetics, we developed a closed-loop experimental apparatus consisting of jacketed tubings used as heat exchangers, three acrylic units to observe the flow, and a slurry pump. The flow rate, salinity, temperature, and pressure in the apparatus were continuously measured in the circulation experiments. The experiment results showed that the freezing condition of the fluid in the pipe is affected by the temperature of the outside of the pipe or the particle in the fluid. This paper reports some experimental data obtained in several cases, including those conducted under freezing conditions.
{"title":"Experimental Study on Plugging Inside a Pipe Using Carbonated Ice as a Substitute for Methane Hydrate","authors":"J. Yamamoto, Marcio Yamamoto, Y. Nakajima, Satoru Takano, S. Kanada, Masao Ono, Kazuhisa Otsubo","doi":"10.1115/omae2021-62164","DOIUrl":"https://doi.org/10.1115/omae2021-62164","url":null,"abstract":"\u0000 Methane hydrate has been found below the seafloor in the Exclusive Economic Zone (EEZ) of Japan in a large amount. During the methane hydrate transportation, it is concerned that the riser pipe or the flowline can be plugged by the hydrate reformation and the freezing of seawater. The degradation and reformation kinetics of methane hydrate are mainly controlled by temperature, pressure, and methane concentration in the system; however, it is difficult to predict these factors in the multiphase flow because they are affected by fluid dynamics and heat transfer. To obtain the experimental data of the degradation kinetics, we developed a closed-loop experimental apparatus consisting of jacketed tubings used as heat exchangers, three acrylic units to observe the flow, and a slurry pump. The flow rate, salinity, temperature, and pressure in the apparatus were continuously measured in the circulation experiments. The experiment results showed that the freezing condition of the fluid in the pipe is affected by the temperature of the outside of the pipe or the particle in the fluid. This paper reports some experimental data obtained in several cases, including those conducted under freezing conditions.","PeriodicalId":269406,"journal":{"name":"Volume 5: Ocean Space Utilization","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127398133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When investigating the characteristics of the fluid force acting on a rotating cylinder in a flow, three-dimensional effects such as edge shape and walls become a problem. In this paper, we investigated the fluid force characteristics of the rotating cylinder, as well as the effect of the flow under the end of the cylinder and the shape of the cylinder end in the water tank experiment. There are three types of experimental conditions: No end flow condition, end flow condition, and condition with end plate. There are five disk-shaped end plates with different diameters, and the changes in fluid force are quantitatively summarized for each ratio between the diameter of the cylinder model and the end plate. By generating a flow under the end of the cylinder, the fluid force is significantly reduced compared to the no end flow condition. By attaching the end plate, the fluid force does not decrease even when a flow is generated under the end of the cylinder. The fluid force increases until the ratio DE/D of the diameter D of the cylinder model and the diameter DE of the end plate is around 3, but after that, it shows a constant value.
{"title":"Experimental Study on the End Effect and the Effect Due to the Difference in End Shape of the Fluid Force Acting on a Rotating Cylinder in a Uniform Flow","authors":"Masahiro Suzuki, T. Ikoma, Y. Aida, C. Rheem","doi":"10.1115/omae2021-62589","DOIUrl":"https://doi.org/10.1115/omae2021-62589","url":null,"abstract":"\u0000 When investigating the characteristics of the fluid force acting on a rotating cylinder in a flow, three-dimensional effects such as edge shape and walls become a problem.\u0000 In this paper, we investigated the fluid force characteristics of the rotating cylinder, as well as the effect of the flow under the end of the cylinder and the shape of the cylinder end in the water tank experiment. There are three types of experimental conditions: No end flow condition, end flow condition, and condition with end plate. There are five disk-shaped end plates with different diameters, and the changes in fluid force are quantitatively summarized for each ratio between the diameter of the cylinder model and the end plate. By generating a flow under the end of the cylinder, the fluid force is significantly reduced compared to the no end flow condition. By attaching the end plate, the fluid force does not decrease even when a flow is generated under the end of the cylinder. The fluid force increases until the ratio DE/D of the diameter D of the cylinder model and the diameter DE of the end plate is around 3, but after that, it shows a constant value.","PeriodicalId":269406,"journal":{"name":"Volume 5: Ocean Space Utilization","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129914286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A commercial-scale Ocean Thermal Energy Conversion (OTEC) floating platform will require a large diameter Cold Water Pipe (CWP) to be attached. Several studies have analyzed the dynamic behavior of the coupled system between the floating platform and the CWP. However, the characteristic of the coupled behavior has not yet been fully understood. This study aims to formulate the coupled system of an OTEC floating plant and simplify the formula to clarify the characteristic of the coupled behavior. The formula is suitable for validation of the numerical simulation results and the preliminary design of an OTEC plant. In the first section of this paper, we derive the equation of motion and equilibrium of the direct moored floating body and an elastic pipe hanged off from the floating body. In the second section, we verify the formula for a 100MW OTEC plantship with 800m length and 12m diameter CWP. The Response Amplitude Operator (RAO) is calculated by solving the equation of motion and statistics responses in 3 hours are compared with a numerical simulation by OrcaFlex. As the result of the comparison, we observed that the present formula is applicable in the early stage of the practical design loop.
{"title":"Simplified Formulation of Coupled System Between Moored Ship and Elastic Pipe for OTEC Plantship","authors":"Ryoya Hisamatsu, T. Utsunomiya","doi":"10.1115/omae2021-62122","DOIUrl":"https://doi.org/10.1115/omae2021-62122","url":null,"abstract":"\u0000 A commercial-scale Ocean Thermal Energy Conversion (OTEC) floating platform will require a large diameter Cold Water Pipe (CWP) to be attached. Several studies have analyzed the dynamic behavior of the coupled system between the floating platform and the CWP. However, the characteristic of the coupled behavior has not yet been fully understood. This study aims to formulate the coupled system of an OTEC floating plant and simplify the formula to clarify the characteristic of the coupled behavior. The formula is suitable for validation of the numerical simulation results and the preliminary design of an OTEC plant. In the first section of this paper, we derive the equation of motion and equilibrium of the direct moored floating body and an elastic pipe hanged off from the floating body. In the second section, we verify the formula for a 100MW OTEC plantship with 800m length and 12m diameter CWP. The Response Amplitude Operator (RAO) is calculated by solving the equation of motion and statistics responses in 3 hours are compared with a numerical simulation by OrcaFlex. As the result of the comparison, we observed that the present formula is applicable in the early stage of the practical design loop.","PeriodicalId":269406,"journal":{"name":"Volume 5: Ocean Space Utilization","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129157828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For subsea mining, it is important to predict the pressure loss in oscillating pipes for the safe and reliable operation of ore lifting as well as the design of lifting system. In the present paper, the authors focused on the internal flow in vertical lifting pipe oscillating in the axial direction and carried out slurry transport experiment to investigate the effects of pipe oscillation on the pressure loss. The spherical alumina beads and glass beads were used as the solid particles in the experiment, and the oscillating periods and amplitudes of pipe model as well as the solid concentrations and the mean slurry velocities were varied. The time-averaged components of hydraulic gradient calculated by the prediction method for the steady flow proposed in the past by the authors agreed well with the experimental ones. As for the fluctuating components of hydraulic gradient, the calculation results using a homogeneous mixture model were compared with the experimental data. The comparison result indicated that the homogeneous mixture model would be applicable to the prediction of pressure loss in the vertical pipe oscillating in the axial direction.
{"title":"Experimental Investigation of Large Particle Slurry Transport in Vertically Oscillating Pipe for Subsea Mining","authors":"Sotaro Masanobu, Satoru Takano, S. Kanada, M. Ono","doi":"10.1115/omae2021-62347","DOIUrl":"https://doi.org/10.1115/omae2021-62347","url":null,"abstract":"\u0000 For subsea mining, it is important to predict the pressure loss in oscillating pipes for the safe and reliable operation of ore lifting as well as the design of lifting system. In the present paper, the authors focused on the internal flow in vertical lifting pipe oscillating in the axial direction and carried out slurry transport experiment to investigate the effects of pipe oscillation on the pressure loss. The spherical alumina beads and glass beads were used as the solid particles in the experiment, and the oscillating periods and amplitudes of pipe model as well as the solid concentrations and the mean slurry velocities were varied. The time-averaged components of hydraulic gradient calculated by the prediction method for the steady flow proposed in the past by the authors agreed well with the experimental ones. As for the fluctuating components of hydraulic gradient, the calculation results using a homogeneous mixture model were compared with the experimental data. The comparison result indicated that the homogeneous mixture model would be applicable to the prediction of pressure loss in the vertical pipe oscillating in the axial direction.","PeriodicalId":269406,"journal":{"name":"Volume 5: Ocean Space Utilization","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125205589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Numerical simulation based on the moving particle semi-implicit (MPS) method is effective for the analysis of floating motion in stormy waves in both coastal and offshore areas. However, when the outer circumference of the calculation area is composed of wall boundaries, superimposed waves are generated by the reflected waves, which makes it difficult to reproduce wave fields in offshore areas. Therefore, in this study, we developed two types of non-reflective boundary that can be applied to a numerical wave tank with the MPS method. One type is an attenuation zone in which a high-viscosity region with a finite width is set from the end of the water tank. The other type is a wave absorption control boundary that detects the amount of water surface fluctuation in front of the boundary and prevents reflection via position control. Regular and irregular waves were created in a numerical wave tank with these boundaries and the wave dissipation performance was quantitatively evaluated by comparing the estimates for incident and reflected waves, the time-series waveform, and the wave spectrum.
{"title":"A Study on Performance Evaluation of Non-Reflective Boundary for Progressive Waves Reproduction Introduced in Numerical Wave Tank With MPS Method","authors":"Y. Aida, Tomotaka Takeo, T. Ikoma, K. Masuda","doi":"10.1115/omae2021-62364","DOIUrl":"https://doi.org/10.1115/omae2021-62364","url":null,"abstract":"\u0000 Numerical simulation based on the moving particle semi-implicit (MPS) method is effective for the analysis of floating motion in stormy waves in both coastal and offshore areas. However, when the outer circumference of the calculation area is composed of wall boundaries, superimposed waves are generated by the reflected waves, which makes it difficult to reproduce wave fields in offshore areas. Therefore, in this study, we developed two types of non-reflective boundary that can be applied to a numerical wave tank with the MPS method. One type is an attenuation zone in which a high-viscosity region with a finite width is set from the end of the water tank. The other type is a wave absorption control boundary that detects the amount of water surface fluctuation in front of the boundary and prevents reflection via position control. Regular and irregular waves were created in a numerical wave tank with these boundaries and the wave dissipation performance was quantitatively evaluated by comparing the estimates for incident and reflected waves, the time-series waveform, and the wave spectrum.","PeriodicalId":269406,"journal":{"name":"Volume 5: Ocean Space Utilization","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129621895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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