Pub Date : 2023-10-26DOI: 10.1080/09377255.2023.2270309
Matteo Diez, Andrea Serani
In shape optimization of complex industrial products (such as, but not limited to, hull forms, rudder and appendages, propellers), there exists an inherent similarity between global optimization (GO) and uncertainty quantification (UQ): they rely on an extensive exploration of the design and operational spaces, respectively; often, they need local refinements to ensure accurate identification of optimal solutions or probability density regions (such as distribution tails), respectively; they both are dramatically affected by the curse of dimensionality as GO and UQ algorithms' complexity and especially computational cost rapidly increase with the problem dimension. Therefore, there exists a natural ground for transferring dimensionality reduction methods from UQ to GO. These enable the efficient exploration of large design spaces in shape optimization, which, in turn, enable global optimization (possibly in a multidisciplinary and stochastic setting). The paper reviews and discusses recent techniques for design-space dimensionality reduction in shape optimization, based on the Karhunen-Loève expansion (equivalent to proper orthogonal decomposition and, at the discrete level, principal component analysis). An example is shown and discussed for the hydrodynamic optimization of a ship hull.
{"title":"Design-space dimensionality reduction in global optimization of functional surfaces: recent developments and way forward","authors":"Matteo Diez, Andrea Serani","doi":"10.1080/09377255.2023.2270309","DOIUrl":"https://doi.org/10.1080/09377255.2023.2270309","url":null,"abstract":"In shape optimization of complex industrial products (such as, but not limited to, hull forms, rudder and appendages, propellers), there exists an inherent similarity between global optimization (GO) and uncertainty quantification (UQ): they rely on an extensive exploration of the design and operational spaces, respectively; often, they need local refinements to ensure accurate identification of optimal solutions or probability density regions (such as distribution tails), respectively; they both are dramatically affected by the curse of dimensionality as GO and UQ algorithms' complexity and especially computational cost rapidly increase with the problem dimension. Therefore, there exists a natural ground for transferring dimensionality reduction methods from UQ to GO. These enable the efficient exploration of large design spaces in shape optimization, which, in turn, enable global optimization (possibly in a multidisciplinary and stochastic setting). The paper reviews and discusses recent techniques for design-space dimensionality reduction in shape optimization, based on the Karhunen-Loève expansion (equivalent to proper orthogonal decomposition and, at the discrete level, principal component analysis). An example is shown and discussed for the hydrodynamic optimization of a ship hull.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136381902","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 acceleration resistance of a vessel advancing in shallow water is investigated. Four acceleration intensities and two water depths are modelled using the CFD and potential flow methods. The results show a pronounced peak in resistance exists near the critical depth Froude number, but its location and magnitude are sensitive to the acceleration intensity and water depth. Excellent agreement between the results obtained from the CFD and potential flow methods is found in the low and high depth Froude number ranges regardless of water depth or acceleration, indicating that linear and unsteady methods can provide robust results at a low cost in those ranges. The magnitude of the resistance peak and its position are sensitive to nonlinear effects, evidenced by slight disagreements between the two adopted methodologies. The variation in the results produced by the two solvers is found to be sensitive to the parameters investigated.
{"title":"The resistance of a trans-critically accelerating ship in shallow water","authors":"Momchil Terziev, Yihan Liu, Zhiming Yuan, Atilla Incecik","doi":"10.1080/09377255.2023.2252232","DOIUrl":"https://doi.org/10.1080/09377255.2023.2252232","url":null,"abstract":"The acceleration resistance of a vessel advancing in shallow water is investigated. Four acceleration intensities and two water depths are modelled using the CFD and potential flow methods. The results show a pronounced peak in resistance exists near the critical depth Froude number, but its location and magnitude are sensitive to the acceleration intensity and water depth. Excellent agreement between the results obtained from the CFD and potential flow methods is found in the low and high depth Froude number ranges regardless of water depth or acceleration, indicating that linear and unsteady methods can provide robust results at a low cost in those ranges. The magnitude of the resistance peak and its position are sensitive to nonlinear effects, evidenced by slight disagreements between the two adopted methodologies. The variation in the results produced by the two solvers is found to be sensitive to the parameters investigated.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135741928","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 : 2023-09-04DOI: 10.1080/09377255.2023.2248721
A. Gürkan, U. Ünal, B. Aktas, M. Atlar
{"title":"An investigation into the gate rudder system design for propulsive performance using design of experiment method","authors":"A. Gürkan, U. Ünal, B. Aktas, M. Atlar","doi":"10.1080/09377255.2023.2248721","DOIUrl":"https://doi.org/10.1080/09377255.2023.2248721","url":null,"abstract":"","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42589570","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 : 2023-08-29DOI: 10.1080/09377255.2023.2250648
G. Anagnostopoulos, P. Kaklis
{"title":"Naval ship design-process analysis through dynamic social networks","authors":"G. Anagnostopoulos, P. Kaklis","doi":"10.1080/09377255.2023.2250648","DOIUrl":"https://doi.org/10.1080/09377255.2023.2250648","url":null,"abstract":"","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43099201","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 : 2023-04-10DOI: 10.1080/09377255.2023.2196042
L. Ferreiro
{"title":"Naval architecture saved The United States at its birth","authors":"L. Ferreiro","doi":"10.1080/09377255.2023.2196042","DOIUrl":"https://doi.org/10.1080/09377255.2023.2196042","url":null,"abstract":"","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46324424","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 : 2023-03-15DOI: 10.1080/09377255.2023.2184049
R. Hamann, J. Cichowicz
ABSTRACT The International Maritime Organization rule-making process utilizes a set of guidelines for the so-called Formal Safety Assessment (FSA). This process is based on a risk assessment and its purpose is to ensure that the risk to human health and life and to marine environment is tolerable. A central instrument in the FSA methodology is known as ALARP (As Low As Reasonably Practicable) principle which ensures that the risk is controlled in a rational and cost-effective manner. The FSA Guidelines recommend the use of monetary thresholds for performing the cost evaluation and provide an example of indices for measuring the cost efficiency. For risks involving fatalities, these measures require the use of a monetary threshold derived from the concept of Cost of Averting a Fatality (CAF). Due to the linkage to economic parameters, this threshold needs to be updated regularly to allow for correct cost-benefit assessment in the FSA context.
{"title":"Updating threshold for IMO cost-benefit assessment","authors":"R. Hamann, J. Cichowicz","doi":"10.1080/09377255.2023.2184049","DOIUrl":"https://doi.org/10.1080/09377255.2023.2184049","url":null,"abstract":"ABSTRACT The International Maritime Organization rule-making process utilizes a set of guidelines for the so-called Formal Safety Assessment (FSA). This process is based on a risk assessment and its purpose is to ensure that the risk to human health and life and to marine environment is tolerable. A central instrument in the FSA methodology is known as ALARP (As Low As Reasonably Practicable) principle which ensures that the risk is controlled in a rational and cost-effective manner. The FSA Guidelines recommend the use of monetary thresholds for performing the cost evaluation and provide an example of indices for measuring the cost efficiency. For risks involving fatalities, these measures require the use of a monetary threshold derived from the concept of Cost of Averting a Fatality (CAF). Due to the linkage to economic parameters, this threshold needs to be updated regularly to allow for correct cost-benefit assessment in the FSA context.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47902749","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 : 2023-03-07DOI: 10.1080/09377255.2023.2180241
H. Söding
ABSTRACT Accurate predictions of the behavior of ships in steep regular waves or in a natural seaway must take into account nonlinear wave responses, especially for roll motions, section moments, and hull vibration excitation. In contrast to CFD methods, here fully nonlinear seakeeping simulations are presented based on potential flow with empirical corrections. This reduces the computing effort by several orders of magnitude. Comparisons with other calculations and model experiments for benchmark cases show that the accuracy of the present method is not worse than that of the best other computations and model experiments. After about ten years of development, the method appears mature for routine applications. The source code of the program is available from the author if an adequate gift is donated to the Mèdecins Sans Frontières.
{"title":"Nonlinear seakeeping and hydroelasticity of ships using potential flow simulations","authors":"H. Söding","doi":"10.1080/09377255.2023.2180241","DOIUrl":"https://doi.org/10.1080/09377255.2023.2180241","url":null,"abstract":"ABSTRACT Accurate predictions of the behavior of ships in steep regular waves or in a natural seaway must take into account nonlinear wave responses, especially for roll motions, section moments, and hull vibration excitation. In contrast to CFD methods, here fully nonlinear seakeeping simulations are presented based on potential flow with empirical corrections. This reduces the computing effort by several orders of magnitude. Comparisons with other calculations and model experiments for benchmark cases show that the accuracy of the present method is not worse than that of the best other computations and model experiments. After about ten years of development, the method appears mature for routine applications. The source code of the program is available from the author if an adequate gift is donated to the Mèdecins Sans Frontières.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45476542","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 : 2023-01-17DOI: 10.1080/09377255.2023.2167537
Luofeng Huang, B. Pena, Giles Thomas
ABSTRACT Computational Fluid Dynamics (CFD) simulations of a ship’s operations are generally conducted at model scale, but the reduced scale changes the fluid behaviour around the ship. Whilst ideally ship simulations should be run directly at full scale, a guide has not been published to advise on the suitable setups that can provide accurate results while minimizing the computational cost. To address this, the present work explores an optimal approach for full-scale ship simulations. Extensive sensitivity studies were conducted on relevant computational setups to investigate their influences on the prediction of ship resistance, ship-generated waves as well as the boundary-layer flow of the hull. A set of CFD setups for full-scale ship simulations in open water was recommended. It was demonstrated that the ideal Y+ and Courant numbers in full scale are evidently different from those given in current model-scale CFD guidelines, indicating the necessity to establish full-scale CFD guidelines separately.
{"title":"Towards a full-scale CFD guideline for simulating a ship advancing in open water","authors":"Luofeng Huang, B. Pena, Giles Thomas","doi":"10.1080/09377255.2023.2167537","DOIUrl":"https://doi.org/10.1080/09377255.2023.2167537","url":null,"abstract":"ABSTRACT Computational Fluid Dynamics (CFD) simulations of a ship’s operations are generally conducted at model scale, but the reduced scale changes the fluid behaviour around the ship. Whilst ideally ship simulations should be run directly at full scale, a guide has not been published to advise on the suitable setups that can provide accurate results while minimizing the computational cost. To address this, the present work explores an optimal approach for full-scale ship simulations. Extensive sensitivity studies were conducted on relevant computational setups to investigate their influences on the prediction of ship resistance, ship-generated waves as well as the boundary-layer flow of the hull. A set of CFD setups for full-scale ship simulations in open water was recommended. It was demonstrated that the ideal Y+ and Courant numbers in full scale are evidently different from those given in current model-scale CFD guidelines, indicating the necessity to establish full-scale CFD guidelines separately.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47174781","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 : 2022-12-24DOI: 10.1080/09377255.2022.2159108
H. Bakka, Hanne Rognebakke, I. Glad, Ingrid Hobæk Haff, E. Vanem
ABSTRACT Marine biofouling on a ship's hull and propeller increases the resistance of the ship moving through water and reduces the propulsion efficiency of the ship. Estimating the effect of fouling is difficult, as the biomass is rarely measured. In this paper, we present a new data-driven model for the total shaft power use of a large containership, in order to estimate the unobserved effect of fouling. Due to the limitations of both physical models and machine learning models, we develop a Bayesian generalized additive model for our purpose. We discuss issues of representative training data for the model. Further, we subset and subsample the data to a representative sample. Models are compared by out-of-sample predictive quality, physical appropriateness, and through autocorrelation of residuals. The Bayesian generalized additive model combined with computational inference using integrated nested Laplace approximations gives a robust estimate of the biofouling effect over time. It also allows a decomposition of the total shaft power use into effects of speed, weather, and other conditions. This model can be used to understand the effectiveness and timing of different hull and propeller treatments.
{"title":"Estimating the effect of biofouling on ship shaft power based on sensor measurements","authors":"H. Bakka, Hanne Rognebakke, I. Glad, Ingrid Hobæk Haff, E. Vanem","doi":"10.1080/09377255.2022.2159108","DOIUrl":"https://doi.org/10.1080/09377255.2022.2159108","url":null,"abstract":"ABSTRACT Marine biofouling on a ship's hull and propeller increases the resistance of the ship moving through water and reduces the propulsion efficiency of the ship. Estimating the effect of fouling is difficult, as the biomass is rarely measured. In this paper, we present a new data-driven model for the total shaft power use of a large containership, in order to estimate the unobserved effect of fouling. Due to the limitations of both physical models and machine learning models, we develop a Bayesian generalized additive model for our purpose. We discuss issues of representative training data for the model. Further, we subset and subsample the data to a representative sample. Models are compared by out-of-sample predictive quality, physical appropriateness, and through autocorrelation of residuals. The Bayesian generalized additive model combined with computational inference using integrated nested Laplace approximations gives a robust estimate of the biofouling effect over time. It also allows a decomposition of the total shaft power use into effects of speed, weather, and other conditions. This model can be used to understand the effectiveness and timing of different hull and propeller treatments.","PeriodicalId":51883,"journal":{"name":"Ship Technology Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43803410","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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