Stefano Lovato, S. Toxopeus, J. Settels, G. Keetels
The ship’s resistance and manoeuvrability in shallow waters can be adversely influenced by the presence of fluid mud layers on the seabed of ports and waterways. Fluid mud exhibits a complex non-Newtonian rheology that is often described using the Herschel–Bulkley model. The latter has been recently implemented in a maritime finite-volume CFD code to study the manoeuvrability of ships in the presence of muddy seabeds. In this paper, we explore the accuracy and robustness of the CFD code in simulating the flow of Herschel–Bulkley fluids, including power-law, Bingham and Newtonian fluids as particular cases. As a stepping stone towards the final maritime applications, the study is carried out on a classic benchmark problem in non-Newtonian fluid mechanics: the laminar flow around a sphere. The aim is to test the performance of the non-Newtonian solver before applying it to the more complex scenarios. Present results could also be used as reference data for future testing. Flow simulations are carried out at low Reynolds numbers in order to compare our results with an extensive collection of data from the literature. Results agree both qualitatively and quantitatively with literature. Difficulties in the convergence of the iterative solver emerged when simulating Bingham and Herschel–Bulkley flows. A simple change in the interpolation of the apparent viscosity has mitigated such difficulties. The results of this work, combined with our previous code verification exercises, suggest that the non-Newtonian solver works as intended and it can be thus employed on more complex applications.
{"title":"Application of a maritime CFD code to a benchmark problem for non-Newtonian fluids: the flow around a sphere","authors":"Stefano Lovato, S. Toxopeus, J. Settels, G. Keetels","doi":"10.3233/isp-220002","DOIUrl":"https://doi.org/10.3233/isp-220002","url":null,"abstract":"The ship’s resistance and manoeuvrability in shallow waters can be adversely influenced by the presence of fluid mud layers on the seabed of ports and waterways. Fluid mud exhibits a complex non-Newtonian rheology that is often described using the Herschel–Bulkley model. The latter has been recently implemented in a maritime finite-volume CFD code to study the manoeuvrability of ships in the presence of muddy seabeds. In this paper, we explore the accuracy and robustness of the CFD code in simulating the flow of Herschel–Bulkley fluids, including power-law, Bingham and Newtonian fluids as particular cases. As a stepping stone towards the final maritime applications, the study is carried out on a classic benchmark problem in non-Newtonian fluid mechanics: the laminar flow around a sphere. The aim is to test the performance of the non-Newtonian solver before applying it to the more complex scenarios. Present results could also be used as reference data for future testing. Flow simulations are carried out at low Reynolds numbers in order to compare our results with an extensive collection of data from the literature. Results agree both qualitatively and quantitatively with literature. Difficulties in the convergence of the iterative solver emerged when simulating Bingham and Herschel–Bulkley flows. A simple change in the interpolation of the apparent viscosity has mitigated such difficulties. The results of this work, combined with our previous code verification exercises, suggest that the non-Newtonian solver works as intended and it can be thus employed on more complex applications.","PeriodicalId":45800,"journal":{"name":"International Shipbuilding Progress","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47667810","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 added resistance is a resistance component that is not yet satisfactorily predicted, although its accurate estimation is crucial – both from an environmental and economic point of view – from the design stage of a ship until its operation. One of the possible sources of overprediction is the occurrence of bow wave breaking. The first aim of this paper is to study the effect of bow wave breaking on added resistance by combining visual observations with resistance tests. On the other hand, as the bow region of a ship appears to be the most dominant contributor to added resistance, this paper introduces a dynamic waterline detection method involving stereo vision. This experimental method is applied to reach the second aim of this paper, which is to stress the importance of the relative wave elevation in the bow region of the ship. By placing stereo rigs inside the hull of a semi-transparent ship, the waterline at each momnent in time can be tracked using an edge detection algorithm. By performing resistance tests on the Delft Systematic Deadrise Series ship model no. 523, the added resistance is observed to be proportional to the relative wave height squared. The data of the experiment and the information necessary to reproduce the experiment are shared through https://doi.org/10.4121/19525852.
{"title":"An experimental study on added resistance focused on the effects of bow wave breaking and relative wave measurements","authors":"Vera Hengelmolen, P. Wellens","doi":"10.3233/isp-210018","DOIUrl":"https://doi.org/10.3233/isp-210018","url":null,"abstract":"The added resistance is a resistance component that is not yet satisfactorily predicted, although its accurate estimation is crucial – both from an environmental and economic point of view – from the design stage of a ship until its operation. One of the possible sources of overprediction is the occurrence of bow wave breaking. The first aim of this paper is to study the effect of bow wave breaking on added resistance by combining visual observations with resistance tests. On the other hand, as the bow region of a ship appears to be the most dominant contributor to added resistance, this paper introduces a dynamic waterline detection method involving stereo vision. This experimental method is applied to reach the second aim of this paper, which is to stress the importance of the relative wave elevation in the bow region of the ship. By placing stereo rigs inside the hull of a semi-transparent ship, the waterline at each momnent in time can be tracked using an edge detection algorithm. By performing resistance tests on the Delft Systematic Deadrise Series ship model no. 523, the added resistance is observed to be proportional to the relative wave height squared. The data of the experiment and the information necessary to reproduce the experiment are shared through https://doi.org/10.4121/19525852.","PeriodicalId":45800,"journal":{"name":"International Shipbuilding Progress","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48122510","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}
Background: Among the challenges for implementation of Waterborne public transportation (WPT) are the difficulties in procuring efficient ferries tailored towards local requirements. Fundamental questions on the ferry’s environmental impact, speed and procurement costs linger in the public transport (PTP) mind. Objective: In this paper, a methodology for adopting a platform architecture for ferries is illustrated by a modular design approach. Methods: For this, WPT operational profiles are categorized by three route types in a structure for operational requirements including sustainability performance. Generic parameters for size and speed of WPT ferries are defined. Using these parameters as a skeletal structure, a modular commuter ferry concept is proposed as a set of basic modules. As a combination of these functionally independent modules, a ferry can be tailored to fit the operational requirements. Results: The paper proposes standard sizes for waterborne commuter craft and shows that ferries are compatible with land-based public transport in terms of energy efficiency and speed. Suitable speed ranges for mono hulls and catamarans are investigated and the idea of modular design for rational procurement is explored and illustrated for the three type routes. Conclusions: The proposed concepts can make WPT more attractive for PTPs as a sustainable option to complement the existing network.
{"title":"A modularly tailored commuter ferry platform","authors":"Harsha Cheemakurthy, K. Garme","doi":"10.3233/isp-210016","DOIUrl":"https://doi.org/10.3233/isp-210016","url":null,"abstract":"Background: Among the challenges for implementation of Waterborne public transportation (WPT) are the difficulties in procuring efficient ferries tailored towards local requirements. Fundamental questions on the ferry’s environmental impact, speed and procurement costs linger in the public transport (PTP) mind. Objective: In this paper, a methodology for adopting a platform architecture for ferries is illustrated by a modular design approach. Methods: For this, WPT operational profiles are categorized by three route types in a structure for operational requirements including sustainability performance. Generic parameters for size and speed of WPT ferries are defined. Using these parameters as a skeletal structure, a modular commuter ferry concept is proposed as a set of basic modules. As a combination of these functionally independent modules, a ferry can be tailored to fit the operational requirements. Results: The paper proposes standard sizes for waterborne commuter craft and shows that ferries are compatible with land-based public transport in terms of energy efficiency and speed. Suitable speed ranges for mono hulls and catamarans are investigated and the idea of modular design for rational procurement is explored and illustrated for the three type routes. Conclusions: The proposed concepts can make WPT more attractive for PTPs as a sustainable option to complement the existing network.","PeriodicalId":45800,"journal":{"name":"International Shipbuilding Progress","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47797961","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}
Hydrodynamic loads acting on a ship can nowadays be reliably obtained from Computational Fluid Dynamics (CFD) techniques. In particular for the determination of the hydrodynamic coefficients of a mathematical manoeuvring model, the forces and moments on a ship sailing at a drift angle or with a yaw rate can be computed efficiently with CFD. While computations with a drift angle are relatively straightforward, computations involving a yaw rate present a challenge. This challenge consists in how to deal with the grid, the setup and the ship encountering its own wake when rotating. A solution based on a single grid setup with consistent boundary conditions and utilising a body force wake damping zone to remedy this challenge is proposed in this paper, leading to an effective, fast, and accurate method to compute hydrodynamic loads of a ship in steady yaw manoeuvres.
{"title":"A technique for efficient computation of steady yaw manoeuvres using CFD","authors":"G. Oud, S. Toxopeus","doi":"10.3233/isp-220001","DOIUrl":"https://doi.org/10.3233/isp-220001","url":null,"abstract":"Hydrodynamic loads acting on a ship can nowadays be reliably obtained from Computational Fluid Dynamics (CFD) techniques. In particular for the determination of the hydrodynamic coefficients of a mathematical manoeuvring model, the forces and moments on a ship sailing at a drift angle or with a yaw rate can be computed efficiently with CFD. While computations with a drift angle are relatively straightforward, computations involving a yaw rate present a challenge. This challenge consists in how to deal with the grid, the setup and the ship encountering its own wake when rotating. A solution based on a single grid setup with consistent boundary conditions and utilising a body force wake damping zone to remedy this challenge is proposed in this paper, leading to an effective, fast, and accurate method to compute hydrodynamic loads of a ship in steady yaw manoeuvres.","PeriodicalId":45800,"journal":{"name":"International Shipbuilding Progress","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48597581","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 topic of evacuation analysis plays an important role in the maritime field, because of its natural link to safety and also because of relevant SOLAS requirements. In this context, this paper focuses on the description, testing and validation of an agent-based mathematical model. As primary goal, the model has been developed targeting a use in evacuation simulations using immersive virtual reality, also with the possibility of real-time human participation. At the same time, the model is suitable also for standard evacuation simulations. The model has been developed starting from existing social force models and introducing a series of improvements, modifications, new modelling, and adaptations. The model is described in detail, providing and discussing all adopted parameters. The choice of a game engine as development environment is also discussed, highlighting benefits and limitations. Results from IMO test cases, validations using experimental data, and comparisons with FDS+Evac are presented. A more realistic test case, relevant to the maritime field, with a two-cabin-deck geometry is also presented, together with corresponding simulation results. Particular attention is paid to the post-processing and reporting of the results from Monte Carlo simulations, in order to properly reflect, quantify and emphasize the underlying aleatory uncertainty.
{"title":"Ship evacuation simulation using a game engine: Modelling, testing and validation","authors":"Gabriele Montecchiari, G. Bulian, P. Gallina","doi":"10.3233/isp-210017","DOIUrl":"https://doi.org/10.3233/isp-210017","url":null,"abstract":"The topic of evacuation analysis plays an important role in the maritime field, because of its natural link to safety and also because of relevant SOLAS requirements. In this context, this paper focuses on the description, testing and validation of an agent-based mathematical model. As primary goal, the model has been developed targeting a use in evacuation simulations using immersive virtual reality, also with the possibility of real-time human participation. At the same time, the model is suitable also for standard evacuation simulations. The model has been developed starting from existing social force models and introducing a series of improvements, modifications, new modelling, and adaptations. The model is described in detail, providing and discussing all adopted parameters. The choice of a game engine as development environment is also discussed, highlighting benefits and limitations. Results from IMO test cases, validations using experimental data, and comparisons with FDS+Evac are presented. A more realistic test case, relevant to the maritime field, with a two-cabin-deck geometry is also presented, together with corresponding simulation results. Particular attention is paid to the post-processing and reporting of the results from Monte Carlo simulations, in order to properly reflect, quantify and emphasize the underlying aleatory uncertainty.","PeriodicalId":45800,"journal":{"name":"International Shipbuilding Progress","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44781952","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}
Alec Bagué, J. Degroote, Toon Demeester, E. Lataire
In this paper an open-source implementation of the vortex-lattice method to perform a dynamic stability analysis for hydrofoil crafts is discussed. The difference with existing vortex-lattice codes is the addition of a free-surface boundary condition which is needed to analyse surface piercing foils. This code, called Typhoon, can be used to perform a dynamic stability analysis (DSA) on hydrofoil vessels. The goal of this code is to have an easy-to-use and cheap alternative to compare different designs in early design stages. This paper gives a brief background to all the concepts used, followed by a short theoretical explanation of the vortex-lattice method. The second part of this paper focuses on a practical example of how this code can be used on an example.
{"title":"Typhoon: A vortex-lattice code for assessing dynamic stability characteristics of hydrofoil crafts","authors":"Alec Bagué, J. Degroote, Toon Demeester, E. Lataire","doi":"10.3233/isp-210006","DOIUrl":"https://doi.org/10.3233/isp-210006","url":null,"abstract":"In this paper an open-source implementation of the vortex-lattice method to perform a dynamic stability analysis for hydrofoil crafts is discussed. The difference with existing vortex-lattice codes is the addition of a free-surface boundary condition which is needed to analyse surface piercing foils. This code, called Typhoon, can be used to perform a dynamic stability analysis (DSA) on hydrofoil vessels. The goal of this code is to have an easy-to-use and cheap alternative to compare different designs in early design stages. This paper gives a brief background to all the concepts used, followed by a short theoretical explanation of the vortex-lattice method. The second part of this paper focuses on a practical example of how this code can be used on an example.","PeriodicalId":45800,"journal":{"name":"International Shipbuilding Progress","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46599311","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}
B. Branowski, M. Zablocki, Jarosław Gabryelski, Andrzej Walczak, P. Kurczewski
Introduction: In connection with the design of a seaworthy yacht for persons with disabilities, authors conduct a risk analysis and consider the safety aspects arising from these risks. In the context of tourism and recreation for people with disabilities, this represents a new issue in the literature. Aim: The aim of the analysis was a multi-aspect evaluation of the hazards that occur when sailors with disabilities carry out typical activities on a yacht. The recommendations arising from the conducted research were used when designing the structure of a staysail schooner intended to be sailed by people with disabilities. Methods: Two methods of risk analysis were adopted. A preliminary hazard analysis (PHA) was carried out with the purpose of identifying and evaluating the possibility of people with various types of disabilities carrying out activities on a yacht. A process hazard analysis (PRHA) was based on a four-degree structure of functions with 31 component operations, relating to both sailing and living on a yacht. This methodology was used by the authors in sailing for the first time when the yacht’s equipment was designed for persons with disabilities. Results: The evaluation covered the adaptation of the yacht for sailing by people with disabilities and considered the various functions that would need to be carried out by these people. A PRHA matrix was created, consisting of 1,116 fields. Authors found that safe execution of many of the relevant functions by people with various types of disabilities was indicated. Conclusions: Based on the results of the PRHA, a set of new guidelines was created for permanent and temporary adaptations of a yacht in the context of the degrees and causes of disabilities.
{"title":"Hazard analysis of a yacht designed for people with disabilities","authors":"B. Branowski, M. Zablocki, Jarosław Gabryelski, Andrzej Walczak, P. Kurczewski","doi":"10.3233/isp-201007","DOIUrl":"https://doi.org/10.3233/isp-201007","url":null,"abstract":"Introduction: In connection with the design of a seaworthy yacht for persons with disabilities, authors conduct a risk analysis and consider the safety aspects arising from these risks. In the context of tourism and recreation for people with disabilities, this represents a new issue in the literature. Aim: The aim of the analysis was a multi-aspect evaluation of the hazards that occur when sailors with disabilities carry out typical activities on a yacht. The recommendations arising from the conducted research were used when designing the structure of a staysail schooner intended to be sailed by people with disabilities. Methods: Two methods of risk analysis were adopted. A preliminary hazard analysis (PHA) was carried out with the purpose of identifying and evaluating the possibility of people with various types of disabilities carrying out activities on a yacht. A process hazard analysis (PRHA) was based on a four-degree structure of functions with 31 component operations, relating to both sailing and living on a yacht. This methodology was used by the authors in sailing for the first time when the yacht’s equipment was designed for persons with disabilities. Results: The evaluation covered the adaptation of the yacht for sailing by people with disabilities and considered the various functions that would need to be carried out by these people. A PRHA matrix was created, consisting of 1,116 fields. Authors found that safe execution of many of the relevant functions by people with various types of disabilities was indicated. Conclusions: Based on the results of the PRHA, a set of new guidelines was created for permanent and temporary adaptations of a yacht in the context of the degrees and causes of disabilities.","PeriodicalId":45800,"journal":{"name":"International Shipbuilding Progress","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42521264","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 order to effectively improve the assembly efficiency for hull blocks, an assembly simulation analysis method considering engineering constraints is proposed in this paper, and an integrated system of shipbuilding accuracy analysis and assembly analysis considering multi-constraints is developed. The method is divided into pre-matching model and fine matching model. In the pre-matching model, an Improved Coherent Point Drift (ICPD) algorithm is used to obtain more accurate initial matching values. The fine matching model firstly uses the Analytic Hierarchy Process (AHP) algorithm to automatically obtain the constrained weights, then the weights vector is used to add the assembly constraints for hull blocks such as straightness, hard point constraints etc. into the multi-objective optimization function. By solving the function, the optimum positioning location and the most reasonable adjustment scheme are obtained. This method shortens the occupancy time of the equipment used to build the hull, reduces the workload of the staff, and improves the efficiency and quality of shipbuilding. The integrated system adds engineering constraints analysis module and the function of automatically finding and eliminating error measurement points. Through the verification of the examples, the integrated system realizes the automation and intellectualization of the assembly for hull blocks.
{"title":"A FAST assembly simulation analysis method for hull blocks with engineering constraints","authors":"Guan Guan, Hongling Liao, Qu Yang","doi":"10.3233/isp-210009","DOIUrl":"https://doi.org/10.3233/isp-210009","url":null,"abstract":"In order to effectively improve the assembly efficiency for hull blocks, an assembly simulation analysis method considering engineering constraints is proposed in this paper, and an integrated system of shipbuilding accuracy analysis and assembly analysis considering multi-constraints is developed. The method is divided into pre-matching model and fine matching model. In the pre-matching model, an Improved Coherent Point Drift (ICPD) algorithm is used to obtain more accurate initial matching values. The fine matching model firstly uses the Analytic Hierarchy Process (AHP) algorithm to automatically obtain the constrained weights, then the weights vector is used to add the assembly constraints for hull blocks such as straightness, hard point constraints etc. into the multi-objective optimization function. By solving the function, the optimum positioning location and the most reasonable adjustment scheme are obtained. This method shortens the occupancy time of the equipment used to build the hull, reduces the workload of the staff, and improves the efficiency and quality of shipbuilding. The integrated system adds engineering constraints analysis module and the function of automatically finding and eliminating error measurement points. Through the verification of the examples, the integrated system realizes the automation and intellectualization of the assembly for hull blocks.","PeriodicalId":45800,"journal":{"name":"International Shipbuilding Progress","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49424108","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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