Pub Date : 2021-05-17DOI: 10.1080/09377255.2021.1927590
Savas Sezen, M. Atlar
ABSTRACT This study focuses on the investigation of cavitating flow around the benchmark INSEAN E779A model propeller with the main aim of further improving the computational efficiency of the tip vortex cavitation (TVC) modelling by using a commercial CFD solver. Also, the effects of various key computational parameters including, numerical modelling, grid size, timestep, water quality and boundary layer resolution, on the TVC formation and its extension in the propeller slipstream are investigated systematically. The numerical simulations are conducted in uniform and open water conditions using RANS, DES and LES solvers implemented in the commercial CFD code, Start CCM+. In order to achieve the aim of the study, an alternative and new Vorticity-based Adaptive Mesh Refinement (V-AMR) technique is introduced for enhanced modelling of the TVC on the blades and downstream. For the CFD modelling of cavitation, the Schneer Sauer cavitation model based on the reduced Rayleigh Plesset equation is used for the sheet, tip and hub vortex cavitation. The hydrodynamic results and cavity patterns are validated with the experimental data. The results show that the application of the V-AMR technique further improves the representation of the TVC with minimal increase in computational cost. However, the eddy viscosity at the propeller blade tips increases with applying the V-AMR technique using the RANS solver due to its inherent modelling errors for the solution of the flow inside the tip vortex. This consequently results in an insufficient extension of TVC in the propeller slipstream compared to the predictions by the DES and LES based numerical solvers. Also, the evolution of the TVC is found to be sensitive to the boundary layer resolution when the standard RANS solver is used. The study will help to widen further applications of the CFD methods involving TVC, particularly for propeller induced underwater noise prediction and analysis.
{"title":"An alternative Vorticity based Adaptive Mesh Refinement (V-AMR) technique for tip vortex cavitation modelling of propellers using CFD methods","authors":"Savas Sezen, M. Atlar","doi":"10.1080/09377255.2021.1927590","DOIUrl":"https://doi.org/10.1080/09377255.2021.1927590","url":null,"abstract":"ABSTRACT This study focuses on the investigation of cavitating flow around the benchmark INSEAN E779A model propeller with the main aim of further improving the computational efficiency of the tip vortex cavitation (TVC) modelling by using a commercial CFD solver. Also, the effects of various key computational parameters including, numerical modelling, grid size, timestep, water quality and boundary layer resolution, on the TVC formation and its extension in the propeller slipstream are investigated systematically. The numerical simulations are conducted in uniform and open water conditions using RANS, DES and LES solvers implemented in the commercial CFD code, Start CCM+. In order to achieve the aim of the study, an alternative and new Vorticity-based Adaptive Mesh Refinement (V-AMR) technique is introduced for enhanced modelling of the TVC on the blades and downstream. For the CFD modelling of cavitation, the Schneer Sauer cavitation model based on the reduced Rayleigh Plesset equation is used for the sheet, tip and hub vortex cavitation. The hydrodynamic results and cavity patterns are validated with the experimental data. The results show that the application of the V-AMR technique further improves the representation of the TVC with minimal increase in computational cost. However, the eddy viscosity at the propeller blade tips increases with applying the V-AMR technique using the RANS solver due to its inherent modelling errors for the solution of the flow inside the tip vortex. This consequently results in an insufficient extension of TVC in the propeller slipstream compared to the predictions by the DES and LES based numerical solvers. Also, the evolution of the TVC is found to be sensitive to the boundary layer resolution when the standard RANS solver is used. The study will help to widen further applications of the CFD methods involving TVC, particularly for propeller induced underwater noise prediction and analysis.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/09377255.2021.1927590","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46447586","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}
Pub Date : 2021-05-12DOI: 10.1080/09377255.2021.1925047
M. Tsujimoto, H. Yasukawa, Kotaku Yamamoto, Tae-il Lee
ABSTRACT With the start of the EEDI (energy efficiency design index for new ships) regulations by the International Maritime Organization, a review of the analysis method for speed/power trials was required. The International Towing Tank Conference (ITTC) Specialist Committee on Performance of Ships in Service has conducted a review since 2011. For wave correction in speed/power trials, various methods were validated to improve correction accuracy during the activities. In this paper, the process of validation and implementation of the wave correction method discussed through the committee is shown. The comparison based on the results of tank test in regular waves, tank test in long-crested irregular waves and speed/power trials of full-scale ships has been examined. From the studies, the features of each method of wave correction are understood, which is helpful for the implementation of the wave correction performed in speed/power trials.
{"title":"Validation of added resistance in waves by tank tests and sea trial data","authors":"M. Tsujimoto, H. Yasukawa, Kotaku Yamamoto, Tae-il Lee","doi":"10.1080/09377255.2021.1925047","DOIUrl":"https://doi.org/10.1080/09377255.2021.1925047","url":null,"abstract":"ABSTRACT With the start of the EEDI (energy efficiency design index for new ships) regulations by the International Maritime Organization, a review of the analysis method for speed/power trials was required. The International Towing Tank Conference (ITTC) Specialist Committee on Performance of Ships in Service has conducted a review since 2011. For wave correction in speed/power trials, various methods were validated to improve correction accuracy during the activities. In this paper, the process of validation and implementation of the wave correction method discussed through the committee is shown. The comparison based on the results of tank test in regular waves, tank test in long-crested irregular waves and speed/power trials of full-scale ships has been examined. From the studies, the features of each method of wave correction are understood, which is helpful for the implementation of the wave correction performed in speed/power trials.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2021-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/09377255.2021.1925047","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47356780","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}
Pub Date : 2021-05-04DOI: 10.1080/09377255.2020.1815140
Í. A. Fonseca, H. Gaspar
ABSTRACT A digital twin is a digital asset that simulates the behaviours of a physical counterpart. Digital twin ship literature identifies that the concept is already being applied to specialised problems, but no clear guide exists for creating broader interdisciplinary digital twins. Relevant dimensions of product data modelling and previous attempts at standardizing ship data elucidate the requirements for effective data modelling in a digital twin context. Such requirements are placed in a broader perspective for digital twin implementation that encompasses challenges and directions for future development of services, networks, and software. Finally, an open standardization for digital twin data is proposed based on lessons extracted from this panorama, proposing its application to a research vessel.
{"title":"Challenges when creating a cohesive digital twin ship: a data modelling perspective","authors":"Í. A. Fonseca, H. Gaspar","doi":"10.1080/09377255.2020.1815140","DOIUrl":"https://doi.org/10.1080/09377255.2020.1815140","url":null,"abstract":"ABSTRACT A digital twin is a digital asset that simulates the behaviours of a physical counterpart. Digital twin ship literature identifies that the concept is already being applied to specialised problems, but no clear guide exists for creating broader interdisciplinary digital twins. Relevant dimensions of product data modelling and previous attempts at standardizing ship data elucidate the requirements for effective data modelling in a digital twin context. Such requirements are placed in a broader perspective for digital twin implementation that encompasses challenges and directions for future development of services, networks, and software. Finally, an open standardization for digital twin data is proposed based on lessons extracted from this panorama, proposing its application to a research vessel.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2021-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/09377255.2020.1815140","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45617368","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}
Pub Date : 2021-04-08DOI: 10.1080/09377255.2021.1904733
P. Fei, Zhang Yuelin, Mu Jinlei, Min Shao-song
ABSTRACT The present work aims to analyse the ultimate strength of cracked stiffened panels under uniaxial tensile load. A series of finite element models of stiffened panels with various plate thickness, crack lengths, crack locations and crack angles are set up. The ultimate strengths are calculated by extended finite element method and the calculated results are compared to results without considering crack propagation. The results show that the thickness has little effect on the ultimate strength of stiffened plates with through cracks. The ultimate load carrying capacity can be overestimated 30–50% without considering crack propagation. The influence of a crack in the plate is larger than that of a crack located in the stiffener. The ultimate strength degrades with the increase of the angle between the crack and the load.
{"title":"Residual load-carrying capacity of stiffened panels with cracks under uniaxial tension loading considering crack propagation","authors":"P. Fei, Zhang Yuelin, Mu Jinlei, Min Shao-song","doi":"10.1080/09377255.2021.1904733","DOIUrl":"https://doi.org/10.1080/09377255.2021.1904733","url":null,"abstract":"ABSTRACT The present work aims to analyse the ultimate strength of cracked stiffened panels under uniaxial tensile load. A series of finite element models of stiffened panels with various plate thickness, crack lengths, crack locations and crack angles are set up. The ultimate strengths are calculated by extended finite element method and the calculated results are compared to results without considering crack propagation. The results show that the thickness has little effect on the ultimate strength of stiffened plates with through cracks. The ultimate load carrying capacity can be overestimated 30–50% without considering crack propagation. The influence of a crack in the plate is larger than that of a crack located in the stiffener. The ultimate strength degrades with the increase of the angle between the crack and the load.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2021-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/09377255.2021.1904733","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47571714","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}
Pub Date : 2021-03-23DOI: 10.1080/09377255.2021.1903128
P. Major, R. Zghyer, Houxiang Zhang, H. P. Hildre
ABSTRACT Virtual prototypes (VPs) are digital models that mock-up existing or conceptual systems' behaviour. In offshore operations, VPs find usages in design, proof of concept for new equipment or method, control system testing, procedure planning, and expert crew training. Moreover, VP can be used in full mission simulators with crews of maritime and offshore engineers, in which case they integrate with control systems such as handles and dynamic positioning systems. Putting the human in the loop sets high requirements for the fidelity of the visual 3D-models and the mathematical models' validity. VPs are thus time-consuming to create and difficult to validate, even based on an existing offshore system. This paper presents an innovative framework for rapid virtual prototyping of ships for hardware and human in the loop simulations and validates the results with data gathered in a sea trial performed on a research vessel, with satisfying results for position keeping. Abbreviations: CLI, Command line interpreter; DP, Dynamic positioning system: ship equipment used to maintain position and heading; DM, Damping matrix; Force FBK, Force Feedback Thruster1; HIL, Hardware in the loop; HITL, Human in the loop; JNI, Java native interface; LC, Loading condition; RAO, Response amplitude operator; RPM, Revolutions per minute; RPM FBK, RPM Feedback Thruster2/3 (Main/Azimuth); SCM, Source code management system; SOG, Speed over ground; VP, Virtual prototyping/prototype; VST, Virtual sea trial; sea trial performed in a simulation
{"title":"A framework for rapid virtual prototyping: a case study with the Gunnerus research vessel","authors":"P. Major, R. Zghyer, Houxiang Zhang, H. P. Hildre","doi":"10.1080/09377255.2021.1903128","DOIUrl":"https://doi.org/10.1080/09377255.2021.1903128","url":null,"abstract":"ABSTRACT Virtual prototypes (VPs) are digital models that mock-up existing or conceptual systems' behaviour. In offshore operations, VPs find usages in design, proof of concept for new equipment or method, control system testing, procedure planning, and expert crew training. Moreover, VP can be used in full mission simulators with crews of maritime and offshore engineers, in which case they integrate with control systems such as handles and dynamic positioning systems. Putting the human in the loop sets high requirements for the fidelity of the visual 3D-models and the mathematical models' validity. VPs are thus time-consuming to create and difficult to validate, even based on an existing offshore system. This paper presents an innovative framework for rapid virtual prototyping of ships for hardware and human in the loop simulations and validates the results with data gathered in a sea trial performed on a research vessel, with satisfying results for position keeping. Abbreviations: CLI, Command line interpreter; DP, Dynamic positioning system: ship equipment used to maintain position and heading; DM, Damping matrix; Force FBK, Force Feedback Thruster1; HIL, Hardware in the loop; HITL, Human in the loop; JNI, Java native interface; LC, Loading condition; RAO, Response amplitude operator; RPM, Revolutions per minute; RPM FBK, RPM Feedback Thruster2/3 (Main/Azimuth); SCM, Source code management system; SOG, Speed over ground; VP, Virtual prototyping/prototype; VST, Virtual sea trial; sea trial performed in a simulation","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2021-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/09377255.2021.1903128","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45822038","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}
Pub Date : 2021-03-04DOI: 10.1080/09377255.2021.1892934
Simone Saettone, B. Taskar, S. Steen, P. Andersen
ABSTRACT The estimation of the thrust deduction fraction is generally conducted in ideal weather conditions. However, the presence of waves considerably alters the magnitude of this propulsive coefficient. The increased load of the propeller could be the main cause for the variation of the thrust deduction fraction in realistic operating conditions. In this work, load-varying self-propulsion model-scale numerical simulations in calm water conditions for the same ship speed are performed to investigate the influence of the propeller loading on the thrust deduction fraction. The single screw model-scale KVLCC2 tanker is selected as the case study. The results reveal a non-linear inverse correlation between the thrust deduction fraction and the propeller loading. A comparison with model-testing conducted on the KVLCC2 tanker in regular head waves suggests that the propeller loading is the main factor influencing the magnitude of the thrust deduction fraction in waves for the considered case vessel.
{"title":"The influence of the propeller loading on the thrust deduction fraction","authors":"Simone Saettone, B. Taskar, S. Steen, P. Andersen","doi":"10.1080/09377255.2021.1892934","DOIUrl":"https://doi.org/10.1080/09377255.2021.1892934","url":null,"abstract":"ABSTRACT The estimation of the thrust deduction fraction is generally conducted in ideal weather conditions. However, the presence of waves considerably alters the magnitude of this propulsive coefficient. The increased load of the propeller could be the main cause for the variation of the thrust deduction fraction in realistic operating conditions. In this work, load-varying self-propulsion model-scale numerical simulations in calm water conditions for the same ship speed are performed to investigate the influence of the propeller loading on the thrust deduction fraction. The single screw model-scale KVLCC2 tanker is selected as the case study. The results reveal a non-linear inverse correlation between the thrust deduction fraction and the propeller loading. A comparison with model-testing conducted on the KVLCC2 tanker in regular head waves suggests that the propeller loading is the main factor influencing the magnitude of the thrust deduction fraction in waves for the considered case vessel.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2021-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/09377255.2021.1892934","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45750400","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}
Pub Date : 2021-02-25DOI: 10.1080/09377255.2021.1892906
Christopher Lewis McGibbon, Md Jahir Rizvi
ABSTRACT Trimaran hulls have some advantageous features over monohull and twin hull counterparts. Naval architects prefer to use axe bow when the achievement of high speed becomes the main design objective as this type of bow cuts through water rather than rising on top of waves. Structural and hydrodynamic behaviours of an axe bow trimaran depend significantly on its design features as well as the operating environment. However, such behaviours are unknown when the hull experiences nearshore wave reflections. Therefore, a scaled-model hull has been tested in coastal wave basin to investigate its behaviour under nearshore wave reflections focusing mainly on the hull’s motions in various heading directions as well as in various wave frequencies. The results presented also relate motions with the wave pressures indicating that an axe bow trimaran hull, travelling near shorelines, experiences unusual motions and wave loadings when it encounters waves influenced by nearshore reflections.
{"title":"Effects of nearshore wave reflections on the behaviour of an axe bow trimaran hull","authors":"Christopher Lewis McGibbon, Md Jahir Rizvi","doi":"10.1080/09377255.2021.1892906","DOIUrl":"https://doi.org/10.1080/09377255.2021.1892906","url":null,"abstract":"ABSTRACT Trimaran hulls have some advantageous features over monohull and twin hull counterparts. Naval architects prefer to use axe bow when the achievement of high speed becomes the main design objective as this type of bow cuts through water rather than rising on top of waves. Structural and hydrodynamic behaviours of an axe bow trimaran depend significantly on its design features as well as the operating environment. However, such behaviours are unknown when the hull experiences nearshore wave reflections. Therefore, a scaled-model hull has been tested in coastal wave basin to investigate its behaviour under nearshore wave reflections focusing mainly on the hull’s motions in various heading directions as well as in various wave frequencies. The results presented also relate motions with the wave pressures indicating that an axe bow trimaran hull, travelling near shorelines, experiences unusual motions and wave loadings when it encounters waves influenced by nearshore reflections.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2021-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/09377255.2021.1892906","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42207398","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}
Pub Date : 2021-02-16DOI: 10.1080/09377255.2021.1883800
A. Soydan, S. Bal
ABSTRACT In this study, scale effects on the hydrodynamic performance of DTMB 4119 propeller have been investigated in uniform flow under non-cavitating and cavitating conditions by a simple practical method based on OpenFOAM. A potential based Lifting Surface Method has also been applied. A verification study of non-cavitating simulations has been carried out by Grid Convergence Index method at one scale ratio. Then the results have been validated with experiments. Schnerr-Sauer cavitation model of OpenFOAM has been used for the phase change between vapor and liquid. Cavitation simulations have been performed as a time-dependent with dynamic mesh while non-cavitating simulations have been carried out as a steady-state with static mesh. Effects of the scale ratio and cavitation simulations have been investigated and a simple fitting procedure on the thrust and torque values based on logarithm of Reynolds number have been applied. Results have also been compared with ITTC corrections.
{"title":"An investigation of scale effects on marine propeller under cavitating and non-cavitating conditions","authors":"A. Soydan, S. Bal","doi":"10.1080/09377255.2021.1883800","DOIUrl":"https://doi.org/10.1080/09377255.2021.1883800","url":null,"abstract":"ABSTRACT In this study, scale effects on the hydrodynamic performance of DTMB 4119 propeller have been investigated in uniform flow under non-cavitating and cavitating conditions by a simple practical method based on OpenFOAM. A potential based Lifting Surface Method has also been applied. A verification study of non-cavitating simulations has been carried out by Grid Convergence Index method at one scale ratio. Then the results have been validated with experiments. Schnerr-Sauer cavitation model of OpenFOAM has been used for the phase change between vapor and liquid. Cavitation simulations have been performed as a time-dependent with dynamic mesh while non-cavitating simulations have been carried out as a steady-state with static mesh. Effects of the scale ratio and cavitation simulations have been investigated and a simple fitting procedure on the thrust and torque values based on logarithm of Reynolds number have been applied. Results have also been compared with ITTC corrections.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2021-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/09377255.2021.1883800","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48305220","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}
Pub Date : 2021-02-16DOI: 10.1080/09377255.2021.1883799
Akhil Balagopalan, P. Krishnankutty
ABSTRACT Manoeuvring behaviour of a vessel changes drastically when it enters from deep water region to a shallow water region. Flow characteristics, around the hull changes and the vessel, respond poorly to the use of control surfaces. Aim of this paper is to study the manoeuvring behavioural changes in a container ship for different water depth conditions. Computational fluid dynamic (CFD) methods are used for simulating static and dynamic captive model tests. Variation in hydrodynamic reaction forces and moments caused by the reduction in water depth and the subsequent effect in hydrodynamic derivatives appearing in the equation of motion are explained in detail. Standard turning circle and zigzag manoeuvring tests are simulated using the CFD generated hydrodynamic derivatives to assess the manoeuvring characteristics of the vessel.
{"title":"Manoeuvring prediction of a container ship in shallow water using numerical planar motion mechanism","authors":"Akhil Balagopalan, P. Krishnankutty","doi":"10.1080/09377255.2021.1883799","DOIUrl":"https://doi.org/10.1080/09377255.2021.1883799","url":null,"abstract":"ABSTRACT Manoeuvring behaviour of a vessel changes drastically when it enters from deep water region to a shallow water region. Flow characteristics, around the hull changes and the vessel, respond poorly to the use of control surfaces. Aim of this paper is to study the manoeuvring behavioural changes in a container ship for different water depth conditions. Computational fluid dynamic (CFD) methods are used for simulating static and dynamic captive model tests. Variation in hydrodynamic reaction forces and moments caused by the reduction in water depth and the subsequent effect in hydrodynamic derivatives appearing in the equation of motion are explained in detail. Standard turning circle and zigzag manoeuvring tests are simulated using the CFD generated hydrodynamic derivatives to assess the manoeuvring characteristics of the vessel.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2021-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/09377255.2021.1883799","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45457212","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}
Pub Date : 2021-01-18DOI: 10.1080/09377255.2021.1872219
Faisal Mehmood Shah, T. Gaggero, M. Gaiotti, C. Rizzo
ABSTRACT Ships condition is assessed regularly to maintain safety. Traditionally, structural integrity assessment is performed by surveyors, requiring complex and time-consuming operations to accessany ship space. Imagery based, three-dimensional (3D) reconstruction of structures is a new area obtaining considerable interest. It can provide low-cost, less disruptive and safer inspection approach. In this study, alternative technologies to generate 3D models, based on photos, are explored. The aim is to highlight how human made ship survey can be improved using robotics technology. A procedure for 3D reconstruction combining photogrammetry/videogrammetry and computer vision techniques is developed, providing an alternative to ease vessel inspections. Moreover, effect of pre-processing image datasets, aimed at improving the performance of 3D reconstruction, is investigated. An efficient image pre-processing pipeline based on computer vision algorithms for colour enhancement, shadow removal and image blurriness is presented. This study can help in effective and reliable decision-making process, due to its user-friendliness and cost effectiveness, mainly for cargo holds requiring frequent assessment because of cargo operations induced damages.
{"title":"Condition assessment of ship structure using robot assisted 3D-reconstruction","authors":"Faisal Mehmood Shah, T. Gaggero, M. Gaiotti, C. Rizzo","doi":"10.1080/09377255.2021.1872219","DOIUrl":"https://doi.org/10.1080/09377255.2021.1872219","url":null,"abstract":"ABSTRACT Ships condition is assessed regularly to maintain safety. Traditionally, structural integrity assessment is performed by surveyors, requiring complex and time-consuming operations to accessany ship space. Imagery based, three-dimensional (3D) reconstruction of structures is a new area obtaining considerable interest. It can provide low-cost, less disruptive and safer inspection approach. In this study, alternative technologies to generate 3D models, based on photos, are explored. The aim is to highlight how human made ship survey can be improved using robotics technology. A procedure for 3D reconstruction combining photogrammetry/videogrammetry and computer vision techniques is developed, providing an alternative to ease vessel inspections. Moreover, effect of pre-processing image datasets, aimed at improving the performance of 3D reconstruction, is investigated. An efficient image pre-processing pipeline based on computer vision algorithms for colour enhancement, shadow removal and image blurriness is presented. This study can help in effective and reliable decision-making process, due to its user-friendliness and cost effectiveness, mainly for cargo holds requiring frequent assessment because of cargo operations induced damages.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2021-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/09377255.2021.1872219","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43774913","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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