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1
Content available Vessel-fender contact force modelling for a real-time ship manoeuvring simulator
Moreno F. M., Sasaki H. A. U., Makiyama H. S., Tannuri E. A.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2023
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Vol. 17 No. 4
813--820
EN
This paper presents the development of a method for calculating the horizontal contact forces between two bodies in a real-time ship manoeuvring simulator. The method was implemented in the simulator of the University of São Paulo, whose computing core is named “Dyna”. The model proposed calculates restoration and friction forces between bodies and has a Momentum-Impulse based criterion to reduce numerical issues when the simulation numerical integration has large time-steps. The model was empirically evaluated at the simulator by deck officers, in real-time simulations with pilots and tugmasters. We also ran simulations of that model to compare its performance under different integration time-steps lengths.
2
Content available Construction and analysis of new mathematical models of the operation of ship propellers in different maneuvering modes
Kryvyi O., Miyusov M. V., Kryvyi M.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2023
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Vol. 17 No. 1
95--102
EN
The influence of the curvilinear movement of the ship on the operation of the propeller was studied. It is shown that even at small values of the drift angle and the angular velocity of the vessel, the transverse component of the force on the propeller and the moment are non-zero and cannot be neglected. The existing and proposed new effective mathematical models of the longitudinal and transverse components of force and moment caused by the operation of the ship's propeller are analyzed. Simple expressions for the coefficients of the propeller thrust and the moment on the propeller shaft, the wake fraction, the thrust-deduction factor, and the flow straightening factor on the propeller at any drift angles and angular velocity are obtained. Numerical analysis of the obtained dimensionless components of forces and moments caused by the operation of the propeller is carried out, and their adequacy is shown. It is shown how the specified parameters change for all possible values of the drift angle and angular velocity. For a few commercial vessels of various types, technical characteristics and calculated dynamic parameters are given for the construction of mathematical models of propeller operation during curvilinear movement of the vessel.
3
Content available Analysis of known and construction of new mathematical models of forces on a ship's rudder in an unbounded flow
Kryvyi O., Miyusov M. V., Kryvyi M.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2023
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Vol. 17 No. 4
831--839
EN
The forces arising on the ship's rudder at different angles of attack in an unbounded flow are investigated. The components of the resulting force on the rudder are represented in terms of the rudder lift and drag forces, as well as in terms of the normal and tangential forces on the rudder. The well-known mathematical models of hydrodynamic rudder coefficients are analyzed, and their disadvantages are found. New mathematical models of hydrodynamic coefficients have been obtained, in particular, the coefficients of rudder lift and drag, which take into account the aspect ratio of the rudder, its relative thickness and can be applied to any angle of attack of the flow on the rudder. On specific examples for rudders of the NACA series, the adequacy of the proposed models and their consistency with known experimental studies are illustrated. It is shown how the rudder lift and drag change, as well as the components of the resulting force for the maximum possible range of changes in the local drift angle and the rudder angle.
4
Content available Simulation in reduced scale hydraulic models of the mooring system of ships docked under the effect of the passage of other vessels (passing ship)
Esferra R., Bernardino J.C.M, Bezerra R., Pion L.M.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2021
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Vol. 15 No. 4
845--852
EN
Vessels moored at port terminals may be subject to excessive strain on mooring lines, induced by other ships passing in their vicinity. This phenomenon is called hydrodynamic interaction, and well known in the international literature as Passing Ship. It occurs due to the displacement of the mass of water between the two vessels, which, consequently, induces hydrodynamic stresses on the two ships. Within this context, scale models are a powerful tool for hydrodynamics studies, being able of reproduce the complex water flow phenomena that take place around passing and moored ship. This paper presents a scale model technique to study the Passing Ship phenomenon and its application on a case study developed for the Santos Port. The study was based on the analysis of the results of simulations performed on a 1:170 scale model to compare the effect of various navigations conditions on the mooring lines of a docked ship.
5
Content available Construction and analysis of mathematical models of hydrodynamic forces and moment on the ship's hull using multivariate regression analysis
Kryvyi O., Miyusov M. V.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2021
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Vol. 15 No. 4
854--864
EN
To analyse the existing mathematical models of hydrodynamic forces and moment on the ship's hull and build new effective ones, an approach based on multivariate regression analysis is suggested. As factors (regressors), various dimensionless ratios of the geometric parameters of the vessel, such as length, breadth, draught, and block coefficient, were taken. When analysing existing mathematical models of hydrodynamic derivatives and building new ones, the value of the multiple correlation coefficient R and the value of standard errors were estimated. The significance of the models and the significance of all factors (regressors) included in the model were assessed using Fisher's and Student's criteria. As a result, new adequate mathematical models have been obtained for hydrodynamic constants with a high degree of correlation and an excellent level of significance of regressors.
6
Content available Hydrodynamic forces on a submerged horizontal circular cylinder in uniform finite depth ice covered water
Sahu M., Das D.
International Journal of Applied Mechanics and Engineering
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2020
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Vol. 25, no. 3
219--227
EN
Hydrodynamic forces on a submerged cylinder in uniform finite depth ice-covered water is formulated by using the method of multipoles, the ice-cover being modelled as an elastic plate of very small thickness. The forces (vertical and horizontal) are obtained analytically as well as numerically and depicted graphically for various values of flexural rigidity of the ice-cover to show the effect of its presence. When the flexural rigidity and surface density of the ice-cover are taken to be zero, then the curves for the forces almost coincide with the curves for the case of uniform finite depth water with free surface.
7
Content available Modification of the Rigid Finite Element Method in Modeling Dynamics of Lines and Risers
Adamiec-Wójcik I., Brzozowska L., Wojciech S.
Archive of Mechanical Engineering
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2013
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Vol. LX, nr 3
409--429
EN
The paper presents an application of the modified rigid finite element method to analysis of the dynamics of slender structures. The equations of motion are formulated for a system discretized by means of the method, and discussion is limited to planar systems and large deformations. Slender elements can be found in offshore engineering as lines, cables and risers. In these cases the hydrostatic influence of water and sea currents has to be taken into account. While analyzing dynamics of risers it may also be necessary to consider the flow of fluid inside the riser. The influence of hydrodynamic coefficients and the velocity of the internal flow of fluid on displacements and forces is presented.
PL
W pracy przedstawiono zastosowanie zmodyfikowanej metody elementów skończonych do analizy dynamiki wiotkich struktur. Sformułowano równania ruchu układu dyskretyzowanego prezentowaną metodą, przy ograniczeniu rozważań do płaskich układów i uwzględnieniu dużych ugięć. Elementy wiotkie spotykane są często w technice offshore’owej jako liny, kable i risery. Analizę dynamiki tych elementów trzeba jednak wówczas uzupełnić o hydrostatyczne oddziaływania wody i prądów morskich. W przypadku riserów, należy też uwzględnić możliwość przepływu płynu w ich wnętrzu. Na przykładzie risera pokazano wpływ współczynników hydrodynamicznych i prędkości przepływu płynu we wnętrzu risera na przemieszczenia i siły.
8
Content available remote External loads for multihull watercraft
Trębacki K., Królicka A.
Vibrations in Physical Systems
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2008
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Vol. 23
371--376
EN
For multihull watercraft, general differential equations of motion were formulated taking into account possible movements of the oceanotechnic construction. These movements are connected with freedom degrees of the construction floating on the undulated sea surface. General formulas given for possible construction movements describe the external loads connected with hydrodynamic reactions, damping forces and hydrostatic reactions. The generalised excitation forces can refer to the case of regular undulation and for this case general formulas are given. Irregular sea undulation, which is a stochastic process, requires using linear filters developed based on parametric wave excitations relating to one of spectra collected in Table 1.
9
Content available remote Parametric analysis of hydrodynamic forces during berthing operations
Abramowicz-Gerigk T.
Journal of KONBiN
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2008
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No. 5 (8)
7-16
EN
Prediction of hydrodynamic forces induced during self-berthing is the most important problem in modelling ship - berth interactions. The paper presents the parametric analysis of these forces, performed using the results of open water model tests and proposed regression models. The study allowed to quantify the importance of examined parameters, necessary in the development of the completed model of interaction forces with aim of its further application in the simulation model of ship manoeuvring motions.
PL
Przewidywanie sił hydrodynamicznych powstających podczas samodzielnego cumowania statku stanowi najistotniejszy problem podczas modelowania sił oddziaływania statek-nabrzeże. W artykule przedstawiono analizę parametryczną tych sił w oparciu o wyniki badań modelowych oraz zaproponowane modele regresyjne. Przeprowadzone badania pozwoliły określić istotność badanych parametrów, potrzebną przy opracowaniu całościowego modelu sił oddziaływania statek-nabrzeże i jego aplikacji w modelu symulacji ruchu statku.
10
Content available Experimental analysis of the effectiveness of ship propulsion devices
Abramowicz-Gerik T.
Annual of Navigation
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2008
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No. 13
5-13
EN
The paper presents the study on the effectiveness of ship propulsion devices based on model tests conducted in the open water experimental set up. The influence of the water depth to draft ratio and distance from the vertical tight wall on the hydrodynamic forces generated by the propellers on the ship hull was investigated. The interaction effects observed for the twin propeller ship in bollard pull condition were compared with the effects induced by single propeller vessels available in literature and discussed with respect to the mathematical modelling of hydrodynamic forces generated on the hull by ship propulsion devices.
11
Content available remote 3D form analysis of rope deformation with long towed underwater hydroacoustic antenna
Bielański J.
Archives of Civil and Mechanical Engineering
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2007
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Vol. 7, no 3
45-54
EN
The article describes a possible solution of the boundary problem for the long rope and underwater hydroacoustic antenna system with density insignificantly greater than the density of the water and small rigidity. There is only known a point of rope connection to the ship and depth on which the end of the towed object is placed. The pap er presents the analysis of the towed antenna system with rope and caIcutation form of the system, forces of weights, buoyancy force and lift with changeable longitudinal rope's tension. The results of calculations give us information about the depth of dip of the antenna end point in function of ship speed and lengths of ropes towing. Other results of antenna bending in horizontal piane allow us to define an error in measurements of antennas. Taking into account this error if will give us better accuracy of the executed measurement by the underwater hydroacoustic antenna towed by a maneuvering ship.
PL
Artykuł opisuje rozwiązanie zagadnienia brzegowego dla zestawu długiej liny holującej i podwodnej anteny hydroakustycznej o gęstości tej ostatniej nieznacznie większej od gęstości wody i małej sztywności. Znane jest tylko położenie punktu zamocowania liny do okrętu (p-kt początkowy holowanego zestawu) oraz głębokość, na której znajduje się koniec anteny. Przedstawiono analizę sił działających na holowany zestaw, ich równania równowagi oraz obliczenia kształtu liny i anteny pod wpływem sił masowych, wyporu hydrostatycznego i hydrodynamicznego z uwzględnieniem zmiennego wzdłużnego napięcia w linie. Wyniki obliczeń pozwalają na predykcję głębokości zanurzenia końca anteny w funkcji prędkości okrętu i długości liny holującej. Ponadto wyniki obliczeń określające deformację kształtu anteny (ugięcie) w płaszczyźnie poziomej umożliwiają określenie błędu pomiaru anteny. Uwzględnienie tego błędu umożliwia uzyskanie dokładniejszych namiarów hydroakustycznej anteny holowanej pod wodą przez manewrujący okręt.
12
Content available Application of potential theory in calculating wave-induced vertical forces on horizontal cylinders near a plane boundary
Marcinkowski T., Wilde P.
Archives of Hydro-Engineering and Environmental Mechanics
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2006
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Vol. 53, nr 1
49-69
EN
Hydrodynamic forces acting on a horizontal cylinder located in the vicinity of the bottom are analyzed by a diffraction theory which solves the problem in terms of a velocity potential. The cylinder is assumed to be rigidly anchored to the bottom at a sufficient depth, so that it has no influence on the surface profile. The potential function φ is defined as the sum of the incident wave velocity potential φ w and the scattered wave velocity potential φa. The results of measurements of wave-induced pressures and forces on a horizontal cylinder located close to the bottom are compared with the theoretical solution based on the potential theory for incompressible, perfect fluid and ideal boundary conditions at the bottom and the surface of the cylinder. The experiments were carried out in the Large Wave Channel in Hannover with a cylinder of 0.8 m diameter. Thus the results are in a scale which corresponds to real pipelines. The analysis shows that the potential theory explains the components with double frequency of the wave in pressures and vertical forces as far as the amplitudes are concerned. In the experiments, the Keulegan-Carpenter number is rather low and the inertia hydrodynamic forces on the cylinder are dominant. It seems that the observed phase shift between the force component and the wave results from the energy dissipation which is not considered in the theoretical solution.
13
Content available On hydrodynamic forces acting on the ship in large motions
Błocki W.
Polish Maritime Research
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2004
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nr 3
7-10
EN
Present stale of mathematical description of ship dynamic non-linear behaviour is preŹsented in this paper with a view to avoiding excessive complications in solving the proŹblem. The non-linearity concerns first of all Froude-Krilov forces and damping forces occurring after entering ship's deck into water or those resulting from drag of bilge keels. And, to the remaining, accompanying and diffraction forces the linear extrapolation has been applied.
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