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{"title":"OMAE2021 Front Matter","authors":"","doi":"10.1115/omae2021-fm6","DOIUrl":"https://doi.org/10.1115/omae2021-fm6","url":null,"abstract":"\u0000 The front matter for this proceedings is available by clicking on the PDF icon.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"63 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79990639","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}
T. Hallak, H. Islam, S. Mohapatra, C. Guedes Soares
In this paper, three methods are used in order to obtain the solution for the propagation of water solitons over finite and variable depth. First, the exact analytical solitary wave solutions of the one-dimensional non-linear Boussinesq equations under shallow water condition are described for constant and variable depth. Second, the three-dimensional Fully Non-linear Potential Flow code OceanWave3D is used in order to obtain the numerical solutions for the solitary waves’ propagation over same depth ranges, providing robust solutions for the potential flow problem. Third, Computational Fluid Dynamics’ tool OpenFOAM is used in order to obtain the viscous solution for the same problem, however, without the accounts of turbulence models. The free-surface profiles are drawn and compared; and the stability of the numerical solutions are assessed. Since the approximations of Boussinesq-type equations depend mainly on the orders of magnitude of amplitude and depth, the numerical-analytical comparison will draw the limits for the validity of the analytical solutions. On the other hand, the comparison will provide the limits where viscous effects start playing an important role, whereas the CFD simulations predict the occurrence of wave breaking. These benchmark cases are compared with past references. After all, results regarding the same phenomena have been described in the literature according to, e.g. Fully Non-linear Boussinesq Models, and Fully Nonlinear Potential Flow schemes solved by Boundary Element Methods. Last but not least, the open source Fully Non-linear Potential Flow code is used in order to provide the potential flow solution for some extra cases of water soliton propagation, in order to capture the trends in weak shoaling scenarios.
{"title":"Comparing Numerical and Analytical Solutions of Solitary Water Waves Over Finite and Variable Depth","authors":"T. Hallak, H. Islam, S. Mohapatra, C. Guedes Soares","doi":"10.1115/omae2021-62642","DOIUrl":"https://doi.org/10.1115/omae2021-62642","url":null,"abstract":"\u0000 In this paper, three methods are used in order to obtain the solution for the propagation of water solitons over finite and variable depth. First, the exact analytical solitary wave solutions of the one-dimensional non-linear Boussinesq equations under shallow water condition are described for constant and variable depth. Second, the three-dimensional Fully Non-linear Potential Flow code OceanWave3D is used in order to obtain the numerical solutions for the solitary waves’ propagation over same depth ranges, providing robust solutions for the potential flow problem. Third, Computational Fluid Dynamics’ tool OpenFOAM is used in order to obtain the viscous solution for the same problem, however, without the accounts of turbulence models. The free-surface profiles are drawn and compared; and the stability of the numerical solutions are assessed. Since the approximations of Boussinesq-type equations depend mainly on the orders of magnitude of amplitude and depth, the numerical-analytical comparison will draw the limits for the validity of the analytical solutions. On the other hand, the comparison will provide the limits where viscous effects start playing an important role, whereas the CFD simulations predict the occurrence of wave breaking. These benchmark cases are compared with past references. After all, results regarding the same phenomena have been described in the literature according to, e.g. Fully Non-linear Boussinesq Models, and Fully Nonlinear Potential Flow schemes solved by Boundary Element Methods. Last but not least, the open source Fully Non-linear Potential Flow code is used in order to provide the potential flow solution for some extra cases of water soliton propagation, in order to capture the trends in weak shoaling scenarios.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87654003","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}
In ship manoeuvrability, the crabbing test is critical to evaluate the hydrodynamic quantities for the guidance of an efficient and safe berthing or unberthing manoeuvres. In the present study, the crabbing performance of a cruise ship is investigated by an unsteady Reynolds-averaged Navier-Stokes (URANS) method considering the instantaneous relative motion between the ship and the quay. In the numerical simulations, the cruise ship is approaching the quay wall at a constant lateral speed. The crabbing motion with five degrees of freedom is modeled by the dynamic overset mesh technique, while the free surface elevation is simulated by the Volume of Fluid method. For reliable predictions of the crabbing performances, the timestep dependency study is conducted and a suitable time step is determined. From the computations, the hydrodynamic performances of the cruise ship, including forces and moments, as well as the surge, sinkage, roll, trim and yaw motions are predicted. The numerical results indicate variations of the hydrodynamic quantities under the impacts of ship speed and blockage effects by the quay wall. The present results can be used to evaluate the crabbing ability of the cruise ship and to provide guidance for estimating and designing the crabbing model test in further investigations.
{"title":"URANS Simulations of a Cruise Ship in Crabbing Motion","authors":"L. Zou, Z. Zou","doi":"10.1115/omae2021-62741","DOIUrl":"https://doi.org/10.1115/omae2021-62741","url":null,"abstract":"\u0000 In ship manoeuvrability, the crabbing test is critical to evaluate the hydrodynamic quantities for the guidance of an efficient and safe berthing or unberthing manoeuvres. In the present study, the crabbing performance of a cruise ship is investigated by an unsteady Reynolds-averaged Navier-Stokes (URANS) method considering the instantaneous relative motion between the ship and the quay. In the numerical simulations, the cruise ship is approaching the quay wall at a constant lateral speed. The crabbing motion with five degrees of freedom is modeled by the dynamic overset mesh technique, while the free surface elevation is simulated by the Volume of Fluid method. For reliable predictions of the crabbing performances, the timestep dependency study is conducted and a suitable time step is determined. From the computations, the hydrodynamic performances of the cruise ship, including forces and moments, as well as the surge, sinkage, roll, trim and yaw motions are predicted. The numerical results indicate variations of the hydrodynamic quantities under the impacts of ship speed and blockage effects by the quay wall. The present results can be used to evaluate the crabbing ability of the cruise ship and to provide guidance for estimating and designing the crabbing model test in further investigations.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87128515","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}
Tubular joints are common in offshore framed structures such as jackets. These joints are subjected to fatigue due to cyclic loads from waves. Stress concentration factor plays a major role in the estimation of fatigue life. Studies have been carried out in the past on stress concentration factors for these joints. However, literature on ring stiffened joints is limited. In the present study, numerical simulations have been carried out on ring stiffened tubular joints, especially the T joints, subjected to axial tension load using finite element method in linear analysis using ABAQUS software. A solid type 20-node quadratic brick element (C3D20R) has been used in the study. Stresses in hotspot locations at brace/chord intersection, ring/chord intersection and ring inner edge are examined. The numerical model has been validated using published experimental data and Lloyd’s register recommendations. Further parametric study has been carried out with 20 models, which includes geometric parameters of ring stiffener such as width of stiffener, thickness of stiffener and spacing between the ring stiffeners. The results of parametric study show a significant reduction of SCF at saddle location by placing ring stiffeners in unstiffened T joint. A set of new parametric equations are developed to calculate SCF for ring stiffened T joint at saddle location for axial tensile load.
{"title":"Parametric Evaluation of Stress Concentration Factor (SCF) at Brace – Chord Intersection of a Ring Stiffened Tubular Joint","authors":"G. Sai krishna, S. Nallayarasu","doi":"10.1115/omae2021-62704","DOIUrl":"https://doi.org/10.1115/omae2021-62704","url":null,"abstract":"\u0000 Tubular joints are common in offshore framed structures such as jackets. These joints are subjected to fatigue due to cyclic loads from waves. Stress concentration factor plays a major role in the estimation of fatigue life. Studies have been carried out in the past on stress concentration factors for these joints. However, literature on ring stiffened joints is limited. In the present study, numerical simulations have been carried out on ring stiffened tubular joints, especially the T joints, subjected to axial tension load using finite element method in linear analysis using ABAQUS software. A solid type 20-node quadratic brick element (C3D20R) has been used in the study. Stresses in hotspot locations at brace/chord intersection, ring/chord intersection and ring inner edge are examined. The numerical model has been validated using published experimental data and Lloyd’s register recommendations. Further parametric study has been carried out with 20 models, which includes geometric parameters of ring stiffener such as width of stiffener, thickness of stiffener and spacing between the ring stiffeners. The results of parametric study show a significant reduction of SCF at saddle location by placing ring stiffeners in unstiffened T joint. A set of new parametric equations are developed to calculate SCF for ring stiffened T joint at saddle location for axial tensile load.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88982196","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}
Flapping hydrofoils in tandem configuration find applications in wave gliders, dragonfly, dorsal-tail fin interaction in fishes, among others. The flapping motion consists of a combination of heaving and pitching motion. This type of motion involves complex interaction of the vortices shed from the upstream hydrofoil with the downstream hydrofoil, thus influencing the performance of the downstream hydrofoil. A two-dimensional stabilized finite element moving mesh framework is utilized for the current study. The important parameters which influence the flow interactions are the chord size ratio and the gap between the hydrofoils. The size ratio is defined as the ratio of the chord of the upstream hydrofoil to that of the downstream hydrofoil. The size ratio is varied from 0.25 to 1. The gap is varied from one chord length to 3 chord lengths of the downstream foil. The study focuses on the effect of the size ratio, gap and flapping kinematics based on sinusoidal heaving and pitching motion on the detailed flow dynamics of the tandem hydrofoils. The effect on the thrust coefficient and hydrodynamic efficiency is explored and compared with that of an isolated hydrofoil. The results obtained from the study can pave way for a better understanding with regard to engineering designs based on biomimetics.
{"title":"Hydrodynamic Analysis of Tandem Flapping Hydrofoils","authors":"V. Joshi, Ravi Chaithanya Mysa","doi":"10.1115/omae2021-62191","DOIUrl":"https://doi.org/10.1115/omae2021-62191","url":null,"abstract":"\u0000 Flapping hydrofoils in tandem configuration find applications in wave gliders, dragonfly, dorsal-tail fin interaction in fishes, among others. The flapping motion consists of a combination of heaving and pitching motion. This type of motion involves complex interaction of the vortices shed from the upstream hydrofoil with the downstream hydrofoil, thus influencing the performance of the downstream hydrofoil. A two-dimensional stabilized finite element moving mesh framework is utilized for the current study. The important parameters which influence the flow interactions are the chord size ratio and the gap between the hydrofoils. The size ratio is defined as the ratio of the chord of the upstream hydrofoil to that of the downstream hydrofoil. The size ratio is varied from 0.25 to 1. The gap is varied from one chord length to 3 chord lengths of the downstream foil. The study focuses on the effect of the size ratio, gap and flapping kinematics based on sinusoidal heaving and pitching motion on the detailed flow dynamics of the tandem hydrofoils. The effect on the thrust coefficient and hydrodynamic efficiency is explored and compared with that of an isolated hydrofoil. The results obtained from the study can pave way for a better understanding with regard to engineering designs based on biomimetics.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86444159","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}
Carlos Eduardo Silva de Souza, N. Fonseca, M. Kvittem
Floating bridges are a promising solution for replacing ferries in the crossing of Norwegian fjords. Their design involves the adoption of accurate, but at the same time efficient models for the loads the structure is subjected to. Wave drift forces at the bridge’s pontoon may excite the bridge’s lower horizontal modes, with consequences to the loads on the bridge and mooring lines. Newman’s approximation is normally adopted to calculate the wave drift forces in such applications. A common simplification is to assume that the pontoons are fixed in the calculation of wave drift coefficients, while it is known that wave frequency motions may significantly influence drift loads. This paper evaluates the consequences of this simplification, in comparison to coefficients obtained considering the pontoons’ motions. First, the effect of the bridge deflection, due to mean drift, on the pontoon’s motions, is evaluated. It is found that this effect is negligible. Then, the RAOs are used in the calculation of wave drift coefficients, showing very different results than those obtained with fixed pontoons. Time-domain simulations are then performed with wave drift coefficients calculated with both approaches, with focus on the bridge girder moments and mooring line tensions. It is shown that using wave drift coefficients obtained with fixed pontoon is a non-conservative simplification, depending on sea state and wave incidence direction.
{"title":"Sensitivity of a Floating Bridge Global Responses to Different Wave Drift Force Models","authors":"Carlos Eduardo Silva de Souza, N. Fonseca, M. Kvittem","doi":"10.1115/omae2021-62777","DOIUrl":"https://doi.org/10.1115/omae2021-62777","url":null,"abstract":"\u0000 Floating bridges are a promising solution for replacing ferries in the crossing of Norwegian fjords. Their design involves the adoption of accurate, but at the same time efficient models for the loads the structure is subjected to. Wave drift forces at the bridge’s pontoon may excite the bridge’s lower horizontal modes, with consequences to the loads on the bridge and mooring lines. Newman’s approximation is normally adopted to calculate the wave drift forces in such applications. A common simplification is to assume that the pontoons are fixed in the calculation of wave drift coefficients, while it is known that wave frequency motions may significantly influence drift loads. This paper evaluates the consequences of this simplification, in comparison to coefficients obtained considering the pontoons’ motions. First, the effect of the bridge deflection, due to mean drift, on the pontoon’s motions, is evaluated. It is found that this effect is negligible. Then, the RAOs are used in the calculation of wave drift coefficients, showing very different results than those obtained with fixed pontoons. Time-domain simulations are then performed with wave drift coefficients calculated with both approaches, with focus on the bridge girder moments and mooring line tensions. It is shown that using wave drift coefficients obtained with fixed pontoon is a non-conservative simplification, depending on sea state and wave incidence direction.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87563785","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}
Open ocean aquaculture cages became recently a promising alternative to traditional fish cage designs. The offshore environment implies larger loads on the structures and higher risk of fish loss. Floating rigid aquaculture cages with stiff nets are considered as a possible solution to cope with these new challenges. Their design process requires more advanced tools to account for the non-linear fluid-structure interaction. This paper presents a suitable numerical approach for analysing the interaction of offshore aquaculture cages and waves using Computational Fluid Dynamics. Here, a numerical wave tank accounts for the accurate propagation of the waves, and structural dynamics solutions are utilised for the cage system. Two-way coupling is enabled by accounting for the influence of the net on the fluid. The numerical model is validated against measurements for the loads on and the responses of a mobile floating fish farm in waves and current.
{"title":"A CFD Approach for Modelling the Fluid-Structure Interaction of Offshore Aquaculture Cages and Waves","authors":"T. Martin, H. Bihs","doi":"10.1115/omae2021-61808","DOIUrl":"https://doi.org/10.1115/omae2021-61808","url":null,"abstract":"\u0000 Open ocean aquaculture cages became recently a promising alternative to traditional fish cage designs. The offshore environment implies larger loads on the structures and higher risk of fish loss. Floating rigid aquaculture cages with stiff nets are considered as a possible solution to cope with these new challenges. Their design process requires more advanced tools to account for the non-linear fluid-structure interaction. This paper presents a suitable numerical approach for analysing the interaction of offshore aquaculture cages and waves using Computational Fluid Dynamics. Here, a numerical wave tank accounts for the accurate propagation of the waves, and structural dynamics solutions are utilised for the cage system. Two-way coupling is enabled by accounting for the influence of the net on the fluid. The numerical model is validated against measurements for the loads on and the responses of a mobile floating fish farm in waves and current.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"89 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78257205","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}
Kristia M. Suriben, J. Klamo, Kathryn I. Yeager, Young W. Kwon
This paper investigates the error incurred by predicting the wave-induced heave forces on a submerged body using a mathematically simple flat face bow and stern rather than the typical curved ones. We examine both theoretically and experimentally how the heave force changes when flat end faces replace hemispheric end caps. We consider bodies with various length-to-diameter ratios to identify the influence that the ratio of the end cap length to the total body length plays on the heave forces. We also consider bodies with forward speed to identify if heave forces are affected by leading edge separation around the blunt front face which is not present for the hemispheric end cap. The theoretical predictions are from an existing potential flow analytical solution while the experimental results were collected in a towing tank with wavemaking capability. The theoretically predicted percent increase in the heave forces caused by the flat end face was confirmed by the experimental results. Finally, the theoretical predictions also showed that the percent increase in the heave force is independent of the forward speed of the body. This was also confirmed with the experimental results.
{"title":"On the Role That the End Shape of an Underwater Vehicle Plays on Wave-Induced Heave Forces","authors":"Kristia M. Suriben, J. Klamo, Kathryn I. Yeager, Young W. Kwon","doi":"10.1115/omae2021-61871","DOIUrl":"https://doi.org/10.1115/omae2021-61871","url":null,"abstract":"\u0000 This paper investigates the error incurred by predicting the wave-induced heave forces on a submerged body using a mathematically simple flat face bow and stern rather than the typical curved ones. We examine both theoretically and experimentally how the heave force changes when flat end faces replace hemispheric end caps. We consider bodies with various length-to-diameter ratios to identify the influence that the ratio of the end cap length to the total body length plays on the heave forces. We also consider bodies with forward speed to identify if heave forces are affected by leading edge separation around the blunt front face which is not present for the hemispheric end cap. The theoretical predictions are from an existing potential flow analytical solution while the experimental results were collected in a towing tank with wavemaking capability. The theoretically predicted percent increase in the heave forces caused by the flat end face was confirmed by the experimental results. Finally, the theoretical predictions also showed that the percent increase in the heave force is independent of the forward speed of the body. This was also confirmed with the experimental results.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"518 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77163079","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 applications of a Smoothed Particle Hydrodynamics (SPH)-based, a Finite Volume Method (FVM)-based and a Boundary Element Method (BEM)-based tools to investigate the nonlinear interactions between large waves and a submerged horizontal circular structure and to some extent a rectangular cylinder at various submergence depths in deep water conditions are presented. The main aim is to validate the Lagrangian technique based SPH tool to predict the wave-structure interaction forces under large waves. The features of typical force curves in a wave cycle, the magnitude of wave forces, and the influence of relative axis depth of the structure in deep water conditions are investigated, primarily using an open-sourced SPH tool. Simulations were carried out in 2D with one deepwater wave at multiple submergence depths. The water surface elevations are predicted at different near- and far-field locations. The time-averaged mean and the average amplitude of the horizontal and vertical forces acting on the cylindrical model at various submergence depths are plotted and then physically interpreted. The wave forces and surface elevations are compared with the available published experimental studies and CFD (both FVM and BEM) predictions. Good agreement between the SPH predictions and the measurements was obtained for the submerged body’s surface elevation and hydrodynamic forces at all submergence depths. The FVM tends to overestimate the wave forces compared to the SPH predictions and the measurements, particularly for the shallowly submerged structure when extreme wave breaking occurs. The BEM predictions are reasonable for the non-wave breaking cases.
{"title":"Modelling and Analysis of Hydrodynamics of a Submerged Structure in Extreme Waves Using a SPH-Based Tool","authors":"Mohammed Islam, D.C. Seo, W. Raman-Nair","doi":"10.1115/omae2021-63034","DOIUrl":"https://doi.org/10.1115/omae2021-63034","url":null,"abstract":"\u0000 The applications of a Smoothed Particle Hydrodynamics (SPH)-based, a Finite Volume Method (FVM)-based and a Boundary Element Method (BEM)-based tools to investigate the nonlinear interactions between large waves and a submerged horizontal circular structure and to some extent a rectangular cylinder at various submergence depths in deep water conditions are presented. The main aim is to validate the Lagrangian technique based SPH tool to predict the wave-structure interaction forces under large waves.\u0000 The features of typical force curves in a wave cycle, the magnitude of wave forces, and the influence of relative axis depth of the structure in deep water conditions are investigated, primarily using an open-sourced SPH tool. Simulations were carried out in 2D with one deepwater wave at multiple submergence depths. The water surface elevations are predicted at different near- and far-field locations. The time-averaged mean and the average amplitude of the horizontal and vertical forces acting on the cylindrical model at various submergence depths are plotted and then physically interpreted. The wave forces and surface elevations are compared with the available published experimental studies and CFD (both FVM and BEM) predictions. Good agreement between the SPH predictions and the measurements was obtained for the submerged body’s surface elevation and hydrodynamic forces at all submergence depths. The FVM tends to overestimate the wave forces compared to the SPH predictions and the measurements, particularly for the shallowly submerged structure when extreme wave breaking occurs. The BEM predictions are reasonable for the non-wave breaking cases.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90318890","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}
Considering the upper structure restraint effect of the floating bridge, the diffraction effect and radiation effect of linear monochromatic waves, the dynamic response equation of floating pier is derived and the factors affecting the dynamic stability of the floating pier are analyzed in this paper. Based on the theory of potential flow, the calculation domain is divided into the interior region and the exterior region. The wave diffraction and radiation problems are solved by the matched eigenfunction expansion method (MEEM). After obtaining the wave excitation force, additional mass and radiation damping coefficient, considering the restraint effect of the upper structure of the floating bridge, the motion differential equation of the floating pier is established, and the response amplitude operator (RAOs) of the floating pier is obtained. The effects of span, mass and stiffness of upper structure, as well as the draft depth, size and net height of floating pier on dynamic stability of floating pier under wave are analyzed. The results show that the increase in the span of upper structure will significantly increase the peak RAOs of sway and heave, and the increase in stiffness is helpful to reduce the peak RAOs of sway and heave. The increase of the floating pier radius can reduce the heave RAO, and the net height on the water surface of the floating pier increases the heave and roll.
{"title":"Study on Dynamic Stability of Single Floating Pier Under Waves","authors":"Yikuan He, Bing Han, Wen-yu Ji","doi":"10.1115/omae2021-62569","DOIUrl":"https://doi.org/10.1115/omae2021-62569","url":null,"abstract":"\u0000 Considering the upper structure restraint effect of the floating bridge, the diffraction effect and radiation effect of linear monochromatic waves, the dynamic response equation of floating pier is derived and the factors affecting the dynamic stability of the floating pier are analyzed in this paper. Based on the theory of potential flow, the calculation domain is divided into the interior region and the exterior region. The wave diffraction and radiation problems are solved by the matched eigenfunction expansion method (MEEM). After obtaining the wave excitation force, additional mass and radiation damping coefficient, considering the restraint effect of the upper structure of the floating bridge, the motion differential equation of the floating pier is established, and the response amplitude operator (RAOs) of the floating pier is obtained. The effects of span, mass and stiffness of upper structure, as well as the draft depth, size and net height of floating pier on dynamic stability of floating pier under wave are analyzed. The results show that the increase in the span of upper structure will significantly increase the peak RAOs of sway and heave, and the increase in stiffness is helpful to reduce the peak RAOs of sway and heave. The increase of the floating pier radius can reduce the heave RAO, and the net height on the water surface of the floating pier increases the heave and roll.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86256909","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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