International Shipbuilding Progress - Volume 60, issue 1-4

Authors: Larsson, Lars

Article Type: Other

DOI: 10.3233/ISP-130103

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 1-1, 2013

Authors: Stern, Frederick | Yang, Jianming | Wang, Zhaoyuan | Sadat-Hosseini, Hamid | Mousaviraad, Maysam | Bhushan, Shanti | Xing, Tao

Article Type: Research Article

Abstract: Computational fluid dynamics for ship hydrodynamics has made monumental progress over the last ten years, which is reaching the milestone of providing first-generation simulation-based design tools with vast capabilities for model- and full-scale simulations and optimization. This is due to the enabling technologies such as free surface tracking/capturing, turbulence modeling, 6DoF motion prediction, dynamic overset grids, local/adaptive grid refinement, high performance computing, environmental modeling and optimization methods. Herein, various modeling, numerical methods, and high performance computing approaches for computational ship hydrodynamics are evaluated thereby providing a vision for the development of the next-generation high-fidelity simulation tools. Verification and validation procedures …and their applications, including resistance and propulsion, seakeeping, maneuvering, and stability and capsize, are reviewed. Issues, opportunities, and challenges for advancements in higher-fidelity two-phase flow are addressed. Fundamental studies for two-phase flows are also discussed. Conclusions and future directions are also provided. Show more

Keywords: CFD, ship hydrodynamics, free-surface/interfacial flow, motion, turbulence, high-fidelity simulation, V&V, captive and free running, wave breaking, spray and air entrainment

DOI: 10.3233/ISP-130090

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 3-105, 2013

Authors: Eça, L. | Hoekstra, M.

Article Type: Research Article

Abstract: This paper discusses Verification and Validation for CFD applications. It emphasizes the differences between the mathematical problem of “solving the equations right” (Verification) and the science/engineering activity of “solving the right equations” (Validation). A clear distinction is made between Code Verification (error evaluation) and Solution Verification (error estimation) and procedures based on grid refinement studies are presented and discussed for both activities. The paper presents examples of Code Verification for Reynolds-Averaged Navier–Stokes solvers using the Method of the Manufactured Solutions; Solution Verification exercises including the KVLCC2 tanker at model and full scale Reynolds number and two examples of the application …of the ASME V&V 20 Validation procedure. This paper is written to stimulate a conscientious approach to CFD in marine applications. Show more

Keywords: Verification, validation, CFD, grid refinement, uncertainty quantification

DOI: 10.3233/ISP-130083

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 107-141, 2013

Authors: Fu, T.C. | O'Shea, T.T. | Judge, C.Q. | Dommermuth, D. | Brucker, K. | Wyatt, D.C.

Article Type: Research Article

Abstract: Over the past few years much progress has been made in Computational Fluid Dynamics (CFD) in its ability to accurately simulate the hydrodynamics associated with a deep-V monohull planing craft. This work has focused on not only predicting the hydrodynamic forces and moments, but also the complex multiphase free-surface flow field generated by a deep-V monohull planing boat at high Froude numbers. One of these state of the art CFD codes is Numerical Flow Analysis (NFA). NFA provides turnkey capabilities to model breaking waves around a ship, including both plunging and spilling breaking waves, the formation of spray and the …entrainment of air. NFA uses a Cartesian-grid formulation with immersed body and volume-of-fluid methods. The focus of this paper is to describe and document a recent effort to assess NFA for the prediction of deep-V planing craft hydrodynamic forces and moments and evaluate how well it models the complex multiphase flows associated with high Froude number flows, specifically the formation of the spray sheet. This detailed validation effort was composed of three parts. The first part focused on assessing NFA's ability to predict pressures on the surface of a 10 degree deadrise wedge during impact with an undisturbed free surface. Detailed comparisons to pressure gauges are presented here for two different drop heights, 15.24 cm (6 in) and 25.4 cm (10 in). Results show NFA accurately predicted pressures during the slamming event. The second part examines NFA's ability to match sinkage, trim and resistance from Fridsma's experiments performed on constant deadrise planing hulls. Simulations were performed on two 20 degree deadrise hullforms of varying length to beam ratios (4 and 5) over a range of speed-length ratios (2, 3, 4, 5 and 6). Results show good agreement with experimentally measured values, as well as values calculated using Savitsky's parametric equations. The final part of the validation study focused on assessing how well NFA was able to accurately model the complex multiphase flow associated with high Froude number flows, specifically the formation of the spray sheet. NFA simulations of a planing hull fixed at various angles of roll (0, 10, 20 and 30 degrees) were compared to experiments. Comparisons to underwater photographs illustrate NFA's ability to model the formation of the spray sheet and the free surface turbulence associated with planing boat hydrodynamics. Overall these three validation studies provide a detailed assessment on the current capabilities of NFA to predict the hydrodynamics of a deep-V planing hull. Show more

Keywords: CFD, planing craft, hydrodynamics

DOI: 10.3233/ISP-130087

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 143-169, 2013

Authors: Chase, Nathan | Michael, Thad | Carrica, Pablo M.

Article Type: Research Article

Abstract: Simulations of the free running submarine model DARPA Suboff in a horizontal overshoot maneuver are presented. To perform the simulations, the fully appended hull was fitted with the conceptual submarine propeller E1619. The overset flow solver CFDShip-Iowa v4.5 was used to perform the computations, including coupling with the propeller code PUF-14. Propeller open water curves were obtained for two grids over a wide range of advance coefficients covering high to moderately low loads, with results compared to available experimental data. The open water curves were also simulated with the coupled CFDShip-Iowa/PUF-14 approach. While computations are performed with delayed detached-eddy …simulation (DDES), simulations with Reynolds-averaged Navier–Stokes (RANS), detached-eddy simulation (DES) and with no turbulence model were also performed. Results show that RANS overly dissipates the wake while the solution with no turbulence model shows unphysical instability in the tip vortices. Overall, open water curves are predicted well by the discretized propeller and by the coupled CFDShip-Iowa/PUF-14 approach. The towed DARPA Suboff hull fitted with sail, rudders and stern planes was simulated and results were compared against experimental data, showing satisfactory results. Self-propulsion computations of the DARPA Suboff fitted with the E1619 propeller were performed and the resulting propeller performance analyzed, both using a rotating gridded propeller and the CFDShip-Iowa/PUF-14 approach. A 20/10 overshoot maneuver is demonstrated with both approaches, showing that the results are similar when the propeller remains close to straight-ahead conditions, but trends between approaches tend to diverge for large wake distortions and low advance ratios. A more complex simulation of a surfacing maneuver of the submarine in waves is demonstrated showing the potential of the approach to tackle simulations including massive free surface deformations in a realistic environment. Show more

Keywords: Overset grids, submarine, propeller, self-propulsion

DOI: 10.3233/ISP-130088

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 171-205, 2013

Authors: Kim, Sung-Eun | Rhee, Bong Jae | Miller, Ronald W.

Article Type: Research Article

Abstract: This study is concerned with the turbulent shear flow around the DARPA SUBOFF body undergoing a turning maneuver at drift. Steady Reynolds-averaged Navier–Stokes (RANS) equations were solved in a rotating frame of reference down to viscous sub-layer using two different k–ω turbulence models. Grid-convergence of the numerical solutions was ascertained using three systematically refined grids with up to 19 mln elements. The Wilcox' k–ω model predictions closely reproduce the salient features of the flow such as the cross-flow separation, the streamwise vortices, and the resultant force and moment acting on the body. The change in the effective drift angle along …the body in turning strengthens cross-flow on the aft body and augments side force. It still remains a challenge to accurately resolve the sail vortex over a long distance. The computations showed measurable effects of the sting on the force and moment. Show more

Keywords: RANS, SUBOFF, maneuvering, drift, turning

DOI: 10.3233/ISP-130100

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 207-231, 2013

Authors: Kim, Keunjae | Leer-Andersen, Michael | Werner, Sofia | Orych, Michal | Choi, Youngbok

Article Type: Research Article

Abstract: With environmental concerns becoming one of the most important issues facing the shipping/ship-building industry today, SSPA has witnessed strong demand for the development of energy saving devices (ESD). SSPA anticipates that the demand will be greater to respond to new requirements set by the IMO regulation on energy efficient design index (EEDI). SSPA has been involved in many joint research projects in developing energy saving solutions. Daewoo Shipbuilding and Marine Engineering Co. Ltd. (DSME) has developed several ESDs in cooperation with SSPA, where SSPA has tested most of the ESDs designed by DSME over the last 10 years. The …pre-swirl stator (PSS) is a device mounted on the stern boss just upstream of the propeller (see Fig. 6 or Fig. 33). It is designed to generate pre-swirl flow to the propeller in order to gain a favorable interaction with the propeller that improves the propulsive efficiency and results in a power reduction. This paper is a full description of one of the developments of PSS from the early design stage, optimization phase, and confirmation by model tests to validation through sea trial tests. Show more

Keywords: Hydrodynamic optimization, Energy Saving Device (ESD), Pre-swirl Stator (PSS), Computational Fluid Dynamic (CFD)

DOI: 10.3233/ISP-130092

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 233-276, 2013

Authors: Kandasamy, Manivannan | Peri, Daniele | Tahara, Yusuke | Wilson, Wesley | Miozzi, Massimo | Georgiev, Svetlozar | Milanov, Evgeni | Campana, Emilio F. | Stern, Frederick

Article Type: Research Article

Abstract: The present work focuses on the application of simulation-based design for the resistance optimization of waterjet propelled Delft catamaran, using integrated computational and experimental fluid dynamics. A variable physics/variable fidelity approach was implemented wherein the objective function was evaluated using both low fidelity potential flow solvers with a simplified CFD waterjet model and high fidelity RANS solvers with discretized duct flow calculations. Both solvers were verified and validated with data for the original hull. The particle swarm optimizer was used for single speed optimization at Fr=0.5, and genetic algorithms were used for multi speed optimization at Fr=0.3, 0.5 and 0.7. …The variable physics/variable fidelity approach was compared with high fidelity approach for the bare-hull shape optimization and it showed an overall CPU time reduction of 54% and converged to the same optimal design at Fr=0.5. The multi-speed optimization showed design improvement at Fr=0.5 and 0.7, but not at Fr=0.3 since the design variables were obtained based on sensitivity analysis at Fr=0.5. High fidelity simulation results for the optimized barehull geometry indicated 4% reduction in resistance and the optimized waterjet equipped geometry indicated 11% reduction in effective pump power required at self-propulsion. Verification was performed for the optimized hull form and its reduction in powering will be validated in forthcoming experimental campaign. Show more

Keywords: Simulation-based design, ship design, waterjet propulsion, variable fidelity

DOI: 10.3233/ISP-130098

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 277-308, 2013

Authors: Zou, L. | Larsson, L.

Article Type: Research Article

Abstract: A ship travelling in canals or narrow channels may encounter hydrodynamic forces and moments caused by a nearby side bank. Since most canals are shallow the effect of the bottom can also be considerable. Knowledge of these effects is crucial for safe navigation. The present paper introduces a study in the framework of a project applying Computational Fluid Dynamics (CFD) in the prediction of confined water effects. Using a steady state Reynolds Averaged Navier–Stokes solver, this study investigates the shallow-water and bank effects on a tanker moving straight ahead at low speed in a canal characterized by surface piercing banks. …The tanker is fitted with a rudder and a propeller at a zero propeller rate and at self-propulsion. In the systematic computations, a series of cases are considered with varying water depth and ship-to-bank distance, as well as different canal configurations. In the computations, the double model approximation is adopted to simulate the flat free surface. The non-rotating propeller is treated as an appendage composed of shaft and blades, while the operating propeller is approximated by body forces, simulated by a lifting line potential flow model. Validation of forces and moments against experimental data has been performed in previous studies. The emphasis of the present paper is placed on the effects on the flow field and the physical explanation of these effects. Show more

Keywords: Confined water effects, computational fluid dynamics, hydrodynamic forces and moments, verification and validation, flow field analysis

DOI: 10.3233/ISP-130101

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 309-343, 2013

Authors: Bark, Göran | Bensow, Rickard E.

Article Type: Research Article

Abstract: In this paper we consider development of cavitation erosion having its origin in sheet cavitation. The discussion includes generation of cloud cavitation from sheet cavitation and how a cloud collapse can be enhanced by energy cascading from the collapse of a glassy sheet cavity into the collapse of a cloud. A decomposition of the cavitation process into crucial parts results in formulation of a conceptual model for description and analysis of the generation of erosion by mixed glassy and cloud cavitation.

Keywords: Sheet and cloud cavitation, cavitation erosion

DOI: 10.3233/ISP-130097

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 345-374, 2013

Authors: Hendrickson, K. | Weymouth, G. | Banerjee, S. | Yue, D.K.-P.

Article Type: Research Article

Abstract: Accurate prediction of the highly-mixed flow in the near field of a surface ship is a challenging and active research topic in Computational Ship Hydrodynamics. The disparity in the time and length scales and the scales of entrainment dictates the use of bubble source and mixed-phase flow models in which the current state of the art models are ad hoc. This paper presents the air entrainment characteristics and multiphase turbulence modeling of the near-field flow of a canonical stern with the inclusion of simple geometry effects. Using state of the art Cartesian-grid numerical methods with the full field equations, high-resolution …two-phase flow data sets of a canonical stern with three different half-beam to draft ratios are simulated down to the scales of bubble entrainment. These data sets are used as the foundation for: (i) characterization of wake structure and near-wake air entrainment of the stern; (ii) analysis of turbulent mass flux in the wake of the stern; and (iii) a priori testing of multiphase turbulence models for turbulent mass flux. We obtain results to show that these techniques enable analysis and physics-based parameterization of near-field air entrainment about surface ships for use in Computational Ship Hydrodynamics. Show more

Keywords: Entrainment, turbulence, wake, iLES, modeling

DOI: 10.3233/ISP-130102

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 375-401, 2013

Authors: Castro, Alejandro M. | Carrica, Pablo M.

Article Type: Research Article

Abstract: The modeling of polydispersed bubbly flows in practical applications requires the resolution of large systems of equations with multiple unknowns. Since the solution to this problem lives in a four dimensional space the number of unknowns increases quickly with finer discretizations. In addition, the problem is highly non-linear, strongly coupled and stiff. In this work a series of novel ideas to solve these issues in a robust and efficient manner is presented. Further, a simulation of the bubbly flow around a real self-propelled ship where the propellers are fully discretized is performed. This highly demanding computation serves as a test …for the ideas presented in this work. Comparisons with available experimental data are shown. Show more

Keywords: Polydispersed flow, bubbly flow, multigroup discretization, ship flow, high performance computing

DOI: 10.3233/ISP-130094

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 403-433, 2013

Authors: Hsiao, C.-T. | Wu, X. | Ma, J. | Chahine, G.L.

Article Type: Research Article

Abstract: Free surface disruption, bubble entrainment, and resulting bubbly wake due to a stationary and moving horizontal jets plunging into a quiescent liquid were studied both numerically and experimentally. The moving jet wake showed significantly different flow characteristics than the stationary jet wake. High speed videos revealed that large vortical structures with entrapped air were generated periodically from the horizontal plunging jet. Each vortical air pocket broke up into multiple bubbles due to local shear flows as it returned toward the free surface and moved downstream. The frequency of the air pocket occurrence was analyzed and found to scale with the …plunging jet flow and geometry conditions. The plunging dynamics was simulated with an Eulerian/Lagrangian one-way coupled two-phase flow model, which included a Level-Set method and a sub-grid bubble entrainment model. These captured free surface dynamics and predicted the bubble generation and entrainment. The flow structures, velocity field, and overall bubble spreading region near the plunging region were well captured by the numerical model. Further improvement on downstream wake flow is being sought through two-way coupling between the two phases since the one-way coupling does not account properly for the effective density. Show more

Keywords: Plunging jet, bubble entrainment, two-phase flow model

DOI: 10.3233/ISP-130093

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 435-469, 2013

Authors: Mäkiharju, S.A. | Perlin, M. | Ceccio, S.L.

Article Type: Research Article

Abstract: Gas cavities, natural and ventilated, can occur on ship propulsors, control surfaces and hulls. These cavities can be significant sources of small bubbles in the ship wake. We present a two-dimensional time resolved X-ray densitometry system developed for investigation of natural, ventilated and mixed cavities. First we consider the limitations and performance of our X-ray system, and compare the measured void fraction to stationary known void fraction, and to data for a ventilated cavity obtained using dual fiber optical probes. Second, we present preliminary data from time-resolved X-ray used to observe the overall dynamics and time dependent void fraction distribution …of a cavitating backward facing step with and without gas injection. Show more

Keywords: Partial cavity, ventilated cavity, X-ray, densitometry, cavitation

DOI: 10.3233/ISP-130086

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 471-494, 2013

Authors: Fullerton, A.M. | Beale, K.L.C. | Terrill, E. | Dommermuth, D.

Article Type: Research Article

Abstract: Wind over the ocean can be divided into two parts: the mean wind and the unsteady, time-varying wind. The unsteady component of the wind profile is not often included when modeling wind and predicting its impact on ship motions, but may have an effect, particularly in extreme cases. The mean velocity profiles for the wind have been thoroughly investigated and documented, however the time varying portion is not as well understood, mostly due to insufficient data. A portion of the time-varying wind is due to wind gusts, which are typically modeled as a Gaussian stochastic process and can be …fully described by a wind gust spectrum [Ocean Engineering 34 (2007), 354–358]. Wind gust spectra measured over land typically have less energy at lower frequencies than measured spectra over the ocean, and this low frequency energy can be important in design of ships and offshore structures. Several wind gust spectra have been proposed, with various dependencies on frequency, height above sea level, and mean wind speed, including Ochi [Proceedings of 20th Offshore Technology Conference, Vol. 2, 1988, pp. 461–467], Wills [Marine Structures 19 (2006), 173–192] and Froya [Marine Structures 19 (2006), 173–192]. These spectra are compared with data collected from the High Resolution Air Sea Interaction (HIRES) research program, sponsored by the Office of Naval Research (ONR), from surface buoy data at 1 m as well as from the R/P FLIP at 30 m above sea level. The various spectra from the literature bound the data at the 1 m level, but all tend to over predict the spectra at the 30 m level. In addition to gusts, the mean wind profile may be modified by the time-varying wave profile, another aspect of wind behavior that can affect the design of ships and offshore structures. Air flow separation over water waves has been observed by many researchers over the years, though a global criterion for separation and a model for the separated flow have not yet been conclusively determined. Evidence in the literature shows that both the wave age and wave slope play a role in separation (for example, in: Proceedings of the ASME 2010 29th International Conference on Ocean, Offshore, and Arctic Engineering, 2010). A separation criterion is proposed, based on data from the literature, as well as a model for the adjusted wind profile based on a separation profile developed for land. The adjusted profile compares well with data from the literature. The criterion and proposed model are also compared with preliminary results from the ONR supported computational fluid dynamics code, Numerical Flow Analysis (NFA). The objective of this numerical effort is to research and develop the capability to couple advanced free-surface hydrodynamic predictions with numerical wind distributions in a marine atmospheric boundary layer. By developing a wind/wave boundary interaction model for the Numerical Flow Analysis (NFA) code, an important step towards carrying out this objective is achieved. It is the final goal of this development to provide a wind/wave interaction prediction capability that includes the possibility of correctly predicting the impact of breaking ambient waves. Show more

Keywords: Wind, waves, NFA

DOI: 10.3233/ISP-130095

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 495-521, 2013

Authors: Degtyarev, Alexander B. | Reed, Arthur M.

Article Type: Research Article

Abstract: The problem of wave climate description and modeling are considered on both a short-term and synoptic basis. The wave climate is considered as an ensemble of conditions of spatio-temporal wave fields characterized by frequency-directional spectra. Using an expanded set of wave and wind characteristics makes it possible to correctly introduce the concept of a wave weather “scenario” and to use it to evaluate vessel safety. The mathematical basis of the short-term wave description is by the representation of the stochastic processes by a generalized autoregressive model (ARM) and related models of periodically correlated random process. An ARM is used to …generate space-time realizations of the wave surface of any short-term duration. Application of the aforesaid model takes into account the true stochastic process (lack of repetition in quasi-steady implementation of the process inherent in other models of wind waves). Ways of treating synoptic and seasonal variability of wave forecasts for a specific geographic region are also described. Here, for the first time using the general positions of stationary wave processes and non-stationary synoptic processes of average wave height variation are combined. In this case we have nested mathematical models of the same type. Show more

Keywords: Autoregressive model (ARM), ocean waves modeling, wave weather “scenario”, synoptic weather model

DOI: 10.3233/ISP-130091

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 523-553, 2013

Authors: Sclavounos, Paul D. | Lee, Sungho

Article Type: Research Article

Abstract: A new nonlinear seakeeping theory is presented for the prediction of the large amplitude motions and wave induced loads on ships in severe seastates. The hydrodynamic forces on the ship are evaluated using a new fluid impulse theory which expresses the nonlinear Froude–Krylov, radiation and diffraction forces as time derivatives of integrals of velocity potentials over the instantaneous ship wetted surface circumventing the time consuming evaluation of the pressure from Bernoulli's equation. Analogous expressions are derived for the structural loads. The free surface problems for the ship wave disturbance are solved on vertical planes fixed relative to an earth fixed …frame using a 2D+t slender body theory. The linear free surface condition is enforced on the ambient wave profile assumed locally horizontal, a nonlinear boundary condition is imposed on the ship hull and the resulting boundary value problem is solved using the two-dimensional time-domain wave source potential. Computations are presented illustrating the performance of the new theory. The application of the theory to the evaluation of the extreme statistics of the ship responses and structural loads in a stochastic seastate is also addressed. Show more

Keywords: Fluid impulse, slender body theory, seakeeping

DOI: 10.3233/ISP-130085

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 555-577, 2013

Authors: Belenky, Vadim | Spyrou, Kostas | Weems, Kenneth M. | Lin, Woei-Min

Article Type: Research Article

Abstract: This paper describes recent progress and issues in the development of the split-time method for predicting the probability of a roll motion stability failure – capsize or extreme roll motion event – for a ship operating in irregular ocean waves. The split-time method attempts to address the challenge presented by the rarity and physical complexity of such events by separating the problem into a sequence of non-rare and rare problems that can be practically characterized with advanced numerical methods. In the broadest terms, the non-rare problem can be described as determining the rate of occurrence of an intermediate event such …as the upcrossing of a threshold roll angle, while the rare problem can be described as determining the probability of capsizing when this intermediate event is realized. The current development of the method focuses on two areas related to the application of this method for nonlinear ship motion in quartering seas. The first area of development is the variation of the ship's roll restoring curve in following or quartering seas, which is a key element in a pure loss of stability event. To incorporate this phenomenon, the split-time method has been reformulated with the intermediate roll threshold and the critical roll rate leading to capsizing after upcrossing described by stochastic processes. The implementation of this method with the results of numerical simulation data has led to several important results, including the understanding that roll and roll rates may be dependent processes in quartering seas and the development of a novel procedure for characterizing distribution of the dependent process at the instant of upcrossing. The second area of development is the probabilistic model of surf-riding, which is a necessary step toward evaluating the probability of capsizing or large roll motion due to broaching-to following surf-riding. Recent results include the evaluation of a suitable wave celerity in irregular seas and the use of the existence or non-existence of surf-riding equilibria to describe a ship's transition into and out of surf-riding. Show more

Keywords: Probability of capsizing, pure loss of stability, surf-riding, split-time method

DOI: 10.3233/ISP-130084

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 579-612, 2013

Authors: Greeley, David S. | Willemann, Simmy D.

Article Type: Research Article

Abstract: The use of lifting potential flow techniques for the calculation of surface ship maneuvering forces in both calm water and waves is presented and demonstrated. By properly treating the trajectory of vorticity shed from salient hull features of slender ships, non-linear forces and moments can be captured using potential flow theory. This approach offers an accurate and rapid turn-around calculation, relative to RANS (Reynolds-Averaged Navier–Stokes) approaches, of maneuvering forces in both calm water and waves.

Keywords: Lifting potential flow, maneuvering forces, weak scatterer

DOI: 10.3233/ISP-130089

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 613-631, 2013

Article Type: Other

Citation: International Shipbuilding Progress, vol. 60, no. 1-4, pp. 633-635, 2013