El presente trabajo es un estudio sobre la maniobrabilidad del buque pesquero en condiciones de a... more El presente trabajo es un estudio sobre la maniobrabilidad del buque pesquero en condiciones de aguas tranquilas, en el cual se simula numéricamente la trayectoria de la embarcación, mediante un modelo matemático no lineal de tercera orden, y se considera solo tres grados de libertad, avance (surge), desvío (sway) y guiñada (yaw), este modelo numérico esta basado en el modelo matemático propuesto por Abkowitz. Este modelo pretende hacer una descripción comprensiva y robusta de las acciones fluidas relevantes para los movimientos simétricos y anti-simétricos del buque. El estudio presenta resultados de las simulaciones numéricas de la trayectoria de un buque en el dominio del tiempo, durante las maniobras estandarizadas de curva de giro, espiral y zig-zag. Consecuentemente estos resultados nos permiten tener algunas conclusiones finales que pueden ser tomadas en cuenta por el ingeniero naval, al momento de querer predecir la buena maniobrabilidad del buque pesquero en su anteproyecto.
Page 1. International Shipbuilding Progress 54 (2007) 207225 207 IOS Press An investigation on r... more Page 1. International Shipbuilding Progress 54 (2007) 207225 207 IOS Press An investigation on roll parametric resonance in regular waves Marcelo AS Neves ∗ and Claudio A. Rodríguez Department of Ocean Engineering ...
The present paper describes an investigation on parametric resonance in head seas in which a new ... more The present paper describes an investigation on parametric resonance in head seas in which a new third-order coupled mathematical model is considered. The restored modes of heave, roll and pitch are contemplated. The discussion is illustrated for the case of a transom stern fishing vessel at different speeds. It is pointed out that numerical simulations employing the new model are successfully compared to experimental results previously obtained for the vessel.
In the simulation of the phenomenon of progressive flooding of a naval artifact, the transitional... more In the simulation of the phenomenon of progressive flooding of a naval artifact, the transitional process must be considered in great detail. At this stage, the initial roll angles are larger and may play an important role in case of flooding when the input window is just at one side of the vessel. In this study, to better understand this phenomenon, the breaking of the dam was simulated numerically in order to study the initial process of flooding. It is very important that the effects of dam breaking and sloshing are considered in the process of flooding as heavy loads are caused by these phenomena.
School of Electrical Engineering Computer Science Science Engineering Faculty, 2007
Page 1. Validation of a Container Ship Model for Parametric Rolling Proceedings of the 9th Intern... more Page 1. Validation of a Container Ship Model for Parametric Rolling Proceedings of the 9th International Ship Stability Workshop 1 Validation of a Container Ship Model for Parametric Rolling Claudio A. Rodríguez Department ...
In the simulation of the phenomenon of progressive flooding of a naval artifact, the transitional... more In the simulation of the phenomenon of progressive flooding of a naval artifact, the transitional process must be considered in great detail. At this stage, the initial roll angles are larger and may play an important role in case of flooding when the input window is just at one side of the vessel. In this study, to better understand this phenomenon, the breaking of the dam was simulated numerically in order to study the initial process of flooding. It is very important that the effects of dam breaking and sloshing are considered in the process of flooding as heavy loads are caused by these phenomena. In general, sloshing and dam breaking are important in the dynamics of ships and offshore platforms. These are factors that may cause the wreck when the ship is in undesirable conditions. The numerical model is based on finite difference method, where the Euler equations are solved using the upwind TVD scheme of Roe (1984) and Sweby (1984). The goal is to present numerical results for ...
RESUMEN La resonancia paramétrica es uno de los fenómenos dinámicos que más ha atraído la atenció... more RESUMEN La resonancia paramétrica es uno de los fenómenos dinámicos que más ha atraído la atención reciente de proyectistas, autoridades marítimas y Sociedades Clasificadoras. Ya desde mediados del siglo pasado varias investigaciones han identificado y contribuido significativamente al entendimiento de este fenómeno, principalmente en mar de popa. Sin embargo, desde que se reportó que la causa de un grave accidente ocurrido con un portacontenedor fue el roll paramétrico en mar de proa, el surgimiento de este fenómeno bajo estas condiciones ganó particular importancia en el proyecto de buques cuyas formas presentan grandes variaciones en torno de la línea de flotación de diseño. Dentro de este tipo de buques se encuadran pesqueros, portacontenedores, buques de pasajeros, entre otros que pueden ver amenazadas su seguridad y operación. Una forma práctica y directa de analizar la susceptibilidad de un buque al roll paramétrico, inclusive durante la etapa de proyecto, es la determinación...
Resumen Recientemente, el Comité de Estabilidad en Olas de la ITTC (Conferencia Internacional de ... more Resumen Recientemente, el Comité de Estabilidad en Olas de la ITTC (Conferencia Internacional de Tanques de Remolque) ha emprendido un nuevo estudio benchmark de códigos numéricos para el análisis de estabilidad intacta en olas extremas. Para esto, un nuevo plan de ensayos experimentales con un buque pesquero de cerco rápido y de formas afinadas, fue realizado en olas regulares de popa, para varios aproamientos y velocidades. Con el objetivo de comparar diferentes códigos numéricos existentes, diversas instituciones internacionales fueron invitadas para someter resultados de sus simulaciones numéricas. El presente artículo muestra una visión preliminar de los resultados comparativos obtenidos mediante un código no-lineal de seis grados de libertad desarrollado por el LabOceano-COPPE/UFRJ, una de las instituciones participantes en dicho estudio. Dicho código, denominado STAB6D, incorpora acoplamientos dinámicos (hasta el tercer orden) de los movimientos de cuerpo rígido del buque en ...
Volume 4: Offshore Geotechnics; Ronald W. Yeung Honoring Symposium on Offshore and Ship Hydrodynamics, 2012
ABSTRACT Spars are widely recognized as an excellent choice for deep water applications due to th... more ABSTRACT Spars are widely recognized as an excellent choice for deep water applications due to their hydrodynamic characteristics. However, some relatively recent works report the occurrence of large motions in the plane perpendicular to wave incidence direction, i.e., not directly excited by waves. These unstable motions have been attributed to Mathieu instabilities, caused by pure hydrostatic variations of the underwater hull geometry. Based on a new approach developed by the Authors for predicting parametric rolling in ships, this nonlinear phenomenon has been investigated for spar platforms. The proposed approach demonstrates analytical and numerically that unstable motions, in fact, may appear, but the mechanism that triggers parametric rolling is not related to variations in the hull hydrostatic characteristics. Nonlinear pressure variations induced by waves passing along the spar introduce parametric excitation. Different from typical ship forms, where this effect is negligible even in very long waves due to shorter draughts, in spars, this excitation can be significant, especially for very long waves. The present paper presents the analytical expressions for roll parametric excitation in spars and numerically explores the proposed approach applied to a typical spar under a wide range of wave heights and periods. Parametric Amplification Domains (PADs) were numerically computed, showing not only the boundaries of the instability regions but also the maximum roll amplitudes.
ABSTRACT Parametric rolling in head seas may lead to large roll angles in few cycles with substan... more ABSTRACT Parametric rolling in head seas may lead to large roll angles in few cycles with substantial coupling of this mode with heave and pitch. The present paper investigates in depth the essential dynamical characteristics governing the complex coupling of the three modes at the first region of instability of the limits of stability. Bifurcation diagrams and Poincaré mappings are employed to investigate the appearance of intermittence, multistability and chaos associated with increased values of wave amplitude. Erosion of the safe basin of the coupled system for some sea conditions is also addressed.
The present paper describes an investigation on parametric resonance in head seas in which a new ... more The present paper describes an investigation on parametric resonance in head seas in which a new third-order coupled mathematical model is considered. The restored modes of heave, roll and pitch are contemplated. The discussion is illustrated for the case of a transom stern fishing vessel at different speeds. It is pointed out that numerical simulations employing the new model are successfully compared to experimental results previously obtained for the vessel.
ABSTRACT In this paper, we study the effect of sloshing in a compartment of a naval artifact. The... more ABSTRACT In this paper, we study the effect of sloshing in a compartment of a naval artifact. The sloshing is of great importance in the dynamics of ships and offshore platforms, it is one of the factors that may cause the capsizing. This happens when the ship is under undesirable conditions, such as progressive flooding or fault conditions. The goal is to represent numerically the effect of sloshing. The numerical code is validated through comparisons with numerical and experimental data obtained in the literature. The numerical model is based on the finite difference method, where the Euler equations are solved using the upwind scheme and TVD (Total Variation Diminishing) Roe (1984) and Sweby (1984). The computer code for 2D represents the effect of sloshing in a closed vessel. To adequately represent the reservoir of the naval artifact, we used a structured computational mesh, where the fluid is forced to move by the excitation applied to the tank, this type of excitation is harmonic in sway. For the 3D computer code, a sloped free surface elevation is used as initial condition. Another attempt to realize the versatility of the computer code was the fall of a sphere of water on the free surface of the tank.
ABSTRACT A new 6-DOF nonlinear mathematical model based on Taylor-series expansions with coupling... more ABSTRACT A new 6-DOF nonlinear mathematical model based on Taylor-series expansions with coupling terms defined up to the third-order is introduced and validatedl for head seas parametric rolling for the case of a fishing vessel and a container vessel. Additionally, a large and deep drafted cylindrical SPAR platform is also simulated. The nonlinear algorithm is systematically simulated for different wave conditions. Parametric amplification domains (PADs) are thus obtained for the three hulls. On a comparative basis some of their main characteristics are then examined: influence of coupling, relevance of third-order coupling terms, impact of roll/roll nonlinearities, influence of wave amplitude, and initial conditions. The main differences in the PADs for the three distinct floating vessels are then interpreted and aspects of interest for the modeling and simulation of different hull forms are discussed.
29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 1, 2010
ABSTRACT The objective of the paper is to apply modern numerical techniques of nonlinear dynamics... more ABSTRACT The objective of the paper is to apply modern numerical techniques of nonlinear dynamics to the problem of control of the roll motion employing U-shaped anti rolling tanks (ART). Parametric rolling in head seas is the focus of the paper. A transom stern small vessel, well known for her tendency to develop strong parametric excitation is investigated. Nonlinear equations are employed to describe the liquid motion inside the tank, the forces and moments generated by the tank on the ship and the coupled ship motions (heave, roll and pitch). These are numerically solved for different initial conditions. An analysis of the dynamical behavior of the vessel with stabilization is presented in the form of numerical limits of stability, safe basins, integrity curves and integrity surfaces. Finally, curves of critical amplitude for different wave tunings are computed. A design procedure for quantitative assessment of the level of parametric rolling mitigation by means of ART’s is discussed.
Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment, 2009
ABSTRACT Limits of stability are a well-known and practical way of looking into the problem of pa... more ABSTRACT Limits of stability are a well-known and practical way of looking into the problem of parametric resonance. In the present paper an in-depth analysis of parametric rolling is presented employing the concept of limits of stability as a tool for improved understanding and assessment of the complex dynamics embedded in the problem of non-linearly coupled parametric rolling in extreme regular seas. A third-order coupled mathematical model is considered. The coupled modes of heave, roll, and pitch are contemplated. By means of the analysis of the linear variational equation derived from the extended third-order model, the appearance of super-harmonics and increased rigidity - proportional to wave amplitude squared - due to third-order terms is demonstrated. The mathematical model is then cast in the form of a Hill's equation. Two important new aspects are addressed: the possible appearance of upper limits to the unstable area of the diagram; and the computation of numerical limits of stability. These new limits are compared with the analytical results. Subsequently, by computing the bifurcation diagrams, the dependence of the limits of stability on the initial conditions is shown. Finally, the basins of attraction corresponding to two internal regions of the domain of unstable motions are computed.
In this paper, the modelling of strong parametric resonance in head seas is investigated. Non-lin... more In this paper, the modelling of strong parametric resonance in head seas is investigated. Non-linear equations of ship motions in waves describing the couplings between heave, roll and pitch are contemplated. A third-order mathematical model is introduced, aimed at describing strong parametric excitation associated with cyclic changes of the ship restoring characteristics. A derivative model is employed to describe the coupled restoring actions up to third order. Non-linear coupling coefficients are analytically derived in terms of hull form characteristics.
El presente trabajo es un estudio sobre la maniobrabilidad del buque pesquero en condiciones de a... more El presente trabajo es un estudio sobre la maniobrabilidad del buque pesquero en condiciones de aguas tranquilas, en el cual se simula numéricamente la trayectoria de la embarcación, mediante un modelo matemático no lineal de tercera orden, y se considera solo tres grados de libertad, avance (surge), desvío (sway) y guiñada (yaw), este modelo numérico esta basado en el modelo matemático propuesto por Abkowitz. Este modelo pretende hacer una descripción comprensiva y robusta de las acciones fluidas relevantes para los movimientos simétricos y anti-simétricos del buque. El estudio presenta resultados de las simulaciones numéricas de la trayectoria de un buque en el dominio del tiempo, durante las maniobras estandarizadas de curva de giro, espiral y zig-zag. Consecuentemente estos resultados nos permiten tener algunas conclusiones finales que pueden ser tomadas en cuenta por el ingeniero naval, al momento de querer predecir la buena maniobrabilidad del buque pesquero en su anteproyecto.
El presente trabajo es un estudio sobre la maniobrabilidad del buque pesquero en condiciones de a... more El presente trabajo es un estudio sobre la maniobrabilidad del buque pesquero en condiciones de aguas tranquilas, en el cual se simula numéricamente la trayectoria de la embarcación, mediante un modelo matemático no lineal de tercera orden, y se considera solo tres grados de libertad, avance (surge), desvío (sway) y guiñada (yaw), este modelo numérico esta basado en el modelo matemático propuesto por Abkowitz. Este modelo pretende hacer una descripción comprensiva y robusta de las acciones fluidas relevantes para los movimientos simétricos y anti-simétricos del buque. El estudio presenta resultados de las simulaciones numéricas de la trayectoria de un buque en el dominio del tiempo, durante las maniobras estandarizadas de curva de giro, espiral y zig-zag. Consecuentemente estos resultados nos permiten tener algunas conclusiones finales que pueden ser tomadas en cuenta por el ingeniero naval, al momento de querer predecir la buena maniobrabilidad del buque pesquero en su anteproyecto.
Page 1. International Shipbuilding Progress 54 (2007) 207225 207 IOS Press An investigation on r... more Page 1. International Shipbuilding Progress 54 (2007) 207225 207 IOS Press An investigation on roll parametric resonance in regular waves Marcelo AS Neves ∗ and Claudio A. Rodríguez Department of Ocean Engineering ...
The present paper describes an investigation on parametric resonance in head seas in which a new ... more The present paper describes an investigation on parametric resonance in head seas in which a new third-order coupled mathematical model is considered. The restored modes of heave, roll and pitch are contemplated. The discussion is illustrated for the case of a transom stern fishing vessel at different speeds. It is pointed out that numerical simulations employing the new model are successfully compared to experimental results previously obtained for the vessel.
In the simulation of the phenomenon of progressive flooding of a naval artifact, the transitional... more In the simulation of the phenomenon of progressive flooding of a naval artifact, the transitional process must be considered in great detail. At this stage, the initial roll angles are larger and may play an important role in case of flooding when the input window is just at one side of the vessel. In this study, to better understand this phenomenon, the breaking of the dam was simulated numerically in order to study the initial process of flooding. It is very important that the effects of dam breaking and sloshing are considered in the process of flooding as heavy loads are caused by these phenomena.
School of Electrical Engineering Computer Science Science Engineering Faculty, 2007
Page 1. Validation of a Container Ship Model for Parametric Rolling Proceedings of the 9th Intern... more Page 1. Validation of a Container Ship Model for Parametric Rolling Proceedings of the 9th International Ship Stability Workshop 1 Validation of a Container Ship Model for Parametric Rolling Claudio A. Rodríguez Department ...
In the simulation of the phenomenon of progressive flooding of a naval artifact, the transitional... more In the simulation of the phenomenon of progressive flooding of a naval artifact, the transitional process must be considered in great detail. At this stage, the initial roll angles are larger and may play an important role in case of flooding when the input window is just at one side of the vessel. In this study, to better understand this phenomenon, the breaking of the dam was simulated numerically in order to study the initial process of flooding. It is very important that the effects of dam breaking and sloshing are considered in the process of flooding as heavy loads are caused by these phenomena. In general, sloshing and dam breaking are important in the dynamics of ships and offshore platforms. These are factors that may cause the wreck when the ship is in undesirable conditions. The numerical model is based on finite difference method, where the Euler equations are solved using the upwind TVD scheme of Roe (1984) and Sweby (1984). The goal is to present numerical results for ...
RESUMEN La resonancia paramétrica es uno de los fenómenos dinámicos que más ha atraído la atenció... more RESUMEN La resonancia paramétrica es uno de los fenómenos dinámicos que más ha atraído la atención reciente de proyectistas, autoridades marítimas y Sociedades Clasificadoras. Ya desde mediados del siglo pasado varias investigaciones han identificado y contribuido significativamente al entendimiento de este fenómeno, principalmente en mar de popa. Sin embargo, desde que se reportó que la causa de un grave accidente ocurrido con un portacontenedor fue el roll paramétrico en mar de proa, el surgimiento de este fenómeno bajo estas condiciones ganó particular importancia en el proyecto de buques cuyas formas presentan grandes variaciones en torno de la línea de flotación de diseño. Dentro de este tipo de buques se encuadran pesqueros, portacontenedores, buques de pasajeros, entre otros que pueden ver amenazadas su seguridad y operación. Una forma práctica y directa de analizar la susceptibilidad de un buque al roll paramétrico, inclusive durante la etapa de proyecto, es la determinación...
Resumen Recientemente, el Comité de Estabilidad en Olas de la ITTC (Conferencia Internacional de ... more Resumen Recientemente, el Comité de Estabilidad en Olas de la ITTC (Conferencia Internacional de Tanques de Remolque) ha emprendido un nuevo estudio benchmark de códigos numéricos para el análisis de estabilidad intacta en olas extremas. Para esto, un nuevo plan de ensayos experimentales con un buque pesquero de cerco rápido y de formas afinadas, fue realizado en olas regulares de popa, para varios aproamientos y velocidades. Con el objetivo de comparar diferentes códigos numéricos existentes, diversas instituciones internacionales fueron invitadas para someter resultados de sus simulaciones numéricas. El presente artículo muestra una visión preliminar de los resultados comparativos obtenidos mediante un código no-lineal de seis grados de libertad desarrollado por el LabOceano-COPPE/UFRJ, una de las instituciones participantes en dicho estudio. Dicho código, denominado STAB6D, incorpora acoplamientos dinámicos (hasta el tercer orden) de los movimientos de cuerpo rígido del buque en ...
Volume 4: Offshore Geotechnics; Ronald W. Yeung Honoring Symposium on Offshore and Ship Hydrodynamics, 2012
ABSTRACT Spars are widely recognized as an excellent choice for deep water applications due to th... more ABSTRACT Spars are widely recognized as an excellent choice for deep water applications due to their hydrodynamic characteristics. However, some relatively recent works report the occurrence of large motions in the plane perpendicular to wave incidence direction, i.e., not directly excited by waves. These unstable motions have been attributed to Mathieu instabilities, caused by pure hydrostatic variations of the underwater hull geometry. Based on a new approach developed by the Authors for predicting parametric rolling in ships, this nonlinear phenomenon has been investigated for spar platforms. The proposed approach demonstrates analytical and numerically that unstable motions, in fact, may appear, but the mechanism that triggers parametric rolling is not related to variations in the hull hydrostatic characteristics. Nonlinear pressure variations induced by waves passing along the spar introduce parametric excitation. Different from typical ship forms, where this effect is negligible even in very long waves due to shorter draughts, in spars, this excitation can be significant, especially for very long waves. The present paper presents the analytical expressions for roll parametric excitation in spars and numerically explores the proposed approach applied to a typical spar under a wide range of wave heights and periods. Parametric Amplification Domains (PADs) were numerically computed, showing not only the boundaries of the instability regions but also the maximum roll amplitudes.
ABSTRACT Parametric rolling in head seas may lead to large roll angles in few cycles with substan... more ABSTRACT Parametric rolling in head seas may lead to large roll angles in few cycles with substantial coupling of this mode with heave and pitch. The present paper investigates in depth the essential dynamical characteristics governing the complex coupling of the three modes at the first region of instability of the limits of stability. Bifurcation diagrams and Poincaré mappings are employed to investigate the appearance of intermittence, multistability and chaos associated with increased values of wave amplitude. Erosion of the safe basin of the coupled system for some sea conditions is also addressed.
The present paper describes an investigation on parametric resonance in head seas in which a new ... more The present paper describes an investigation on parametric resonance in head seas in which a new third-order coupled mathematical model is considered. The restored modes of heave, roll and pitch are contemplated. The discussion is illustrated for the case of a transom stern fishing vessel at different speeds. It is pointed out that numerical simulations employing the new model are successfully compared to experimental results previously obtained for the vessel.
ABSTRACT In this paper, we study the effect of sloshing in a compartment of a naval artifact. The... more ABSTRACT In this paper, we study the effect of sloshing in a compartment of a naval artifact. The sloshing is of great importance in the dynamics of ships and offshore platforms, it is one of the factors that may cause the capsizing. This happens when the ship is under undesirable conditions, such as progressive flooding or fault conditions. The goal is to represent numerically the effect of sloshing. The numerical code is validated through comparisons with numerical and experimental data obtained in the literature. The numerical model is based on the finite difference method, where the Euler equations are solved using the upwind scheme and TVD (Total Variation Diminishing) Roe (1984) and Sweby (1984). The computer code for 2D represents the effect of sloshing in a closed vessel. To adequately represent the reservoir of the naval artifact, we used a structured computational mesh, where the fluid is forced to move by the excitation applied to the tank, this type of excitation is harmonic in sway. For the 3D computer code, a sloped free surface elevation is used as initial condition. Another attempt to realize the versatility of the computer code was the fall of a sphere of water on the free surface of the tank.
ABSTRACT A new 6-DOF nonlinear mathematical model based on Taylor-series expansions with coupling... more ABSTRACT A new 6-DOF nonlinear mathematical model based on Taylor-series expansions with coupling terms defined up to the third-order is introduced and validatedl for head seas parametric rolling for the case of a fishing vessel and a container vessel. Additionally, a large and deep drafted cylindrical SPAR platform is also simulated. The nonlinear algorithm is systematically simulated for different wave conditions. Parametric amplification domains (PADs) are thus obtained for the three hulls. On a comparative basis some of their main characteristics are then examined: influence of coupling, relevance of third-order coupling terms, impact of roll/roll nonlinearities, influence of wave amplitude, and initial conditions. The main differences in the PADs for the three distinct floating vessels are then interpreted and aspects of interest for the modeling and simulation of different hull forms are discussed.
29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 1, 2010
ABSTRACT The objective of the paper is to apply modern numerical techniques of nonlinear dynamics... more ABSTRACT The objective of the paper is to apply modern numerical techniques of nonlinear dynamics to the problem of control of the roll motion employing U-shaped anti rolling tanks (ART). Parametric rolling in head seas is the focus of the paper. A transom stern small vessel, well known for her tendency to develop strong parametric excitation is investigated. Nonlinear equations are employed to describe the liquid motion inside the tank, the forces and moments generated by the tank on the ship and the coupled ship motions (heave, roll and pitch). These are numerically solved for different initial conditions. An analysis of the dynamical behavior of the vessel with stabilization is presented in the form of numerical limits of stability, safe basins, integrity curves and integrity surfaces. Finally, curves of critical amplitude for different wave tunings are computed. A design procedure for quantitative assessment of the level of parametric rolling mitigation by means of ART’s is discussed.
Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment, 2009
ABSTRACT Limits of stability are a well-known and practical way of looking into the problem of pa... more ABSTRACT Limits of stability are a well-known and practical way of looking into the problem of parametric resonance. In the present paper an in-depth analysis of parametric rolling is presented employing the concept of limits of stability as a tool for improved understanding and assessment of the complex dynamics embedded in the problem of non-linearly coupled parametric rolling in extreme regular seas. A third-order coupled mathematical model is considered. The coupled modes of heave, roll, and pitch are contemplated. By means of the analysis of the linear variational equation derived from the extended third-order model, the appearance of super-harmonics and increased rigidity - proportional to wave amplitude squared - due to third-order terms is demonstrated. The mathematical model is then cast in the form of a Hill's equation. Two important new aspects are addressed: the possible appearance of upper limits to the unstable area of the diagram; and the computation of numerical limits of stability. These new limits are compared with the analytical results. Subsequently, by computing the bifurcation diagrams, the dependence of the limits of stability on the initial conditions is shown. Finally, the basins of attraction corresponding to two internal regions of the domain of unstable motions are computed.
In this paper, the modelling of strong parametric resonance in head seas is investigated. Non-lin... more In this paper, the modelling of strong parametric resonance in head seas is investigated. Non-linear equations of ship motions in waves describing the couplings between heave, roll and pitch are contemplated. A third-order mathematical model is introduced, aimed at describing strong parametric excitation associated with cyclic changes of the ship restoring characteristics. A derivative model is employed to describe the coupled restoring actions up to third order. Non-linear coupling coefficients are analytically derived in terms of hull form characteristics.
El presente trabajo es un estudio sobre la maniobrabilidad del buque pesquero en condiciones de a... more El presente trabajo es un estudio sobre la maniobrabilidad del buque pesquero en condiciones de aguas tranquilas, en el cual se simula numéricamente la trayectoria de la embarcación, mediante un modelo matemático no lineal de tercera orden, y se considera solo tres grados de libertad, avance (surge), desvío (sway) y guiñada (yaw), este modelo numérico esta basado en el modelo matemático propuesto por Abkowitz. Este modelo pretende hacer una descripción comprensiva y robusta de las acciones fluidas relevantes para los movimientos simétricos y anti-simétricos del buque. El estudio presenta resultados de las simulaciones numéricas de la trayectoria de un buque en el dominio del tiempo, durante las maniobras estandarizadas de curva de giro, espiral y zig-zag. Consecuentemente estos resultados nos permiten tener algunas conclusiones finales que pueden ser tomadas en cuenta por el ingeniero naval, al momento de querer predecir la buena maniobrabilidad del buque pesquero en su anteproyecto.
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