Ship motions using single-phase level set with dynamic overset grids
TL;DR: In this article, the problem of surface ships free to pitch and heave in regular head waves is analyzed numerically with an unsteady Reynolds averaged Navier Stokes (URANS) approach.
About: This article is published in Computers & Fluids.The article was published on 2007-11-01. It has received 265 citations till now. The article focuses on the topics: Ship motions & Froude number.
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TL;DR: In this paper, the authors performed a fully nonlinear unsteady RANS simulation to predict the ship motions and added resistance of a full scale KRISO container ship model, and to estimate the increase in effective power and fuel consumption due to its operation in waves.
287 citations
TL;DR: In this article, an implementation of the dynamic overset grid technique into naoe-FOAM-SJTU solver developed by using the open source code OpenFOAM is presented.
191 citations
TL;DR: In this article, simulations of the National Renewable Energy Laboratory (NREL) phase VI wind turbine using dynamic oversetgrid technology are presented, with the rotor consisting of the blades and hub.
189 citations
TL;DR: In this paper, the motions and added resistance of KVLCC2 at Fr=0.142 and 0.25 with free and fixed surge in short and long head waves are predicted using URANS and validated against EFD data for Fr = 0.142.
165 citations
TL;DR: In this article, the KCS container ship was investigated in calm water and regular head seas by means of EFD and CFD, and the experimental study was conducted in FORCE Technology's towing tank in Denmark.
Abstract: The KCS container ship was investigated in calm water and regular head seas by means of EFD and CFD. The experimental study was conducted in FORCE Technology’s towing tank in Denmark, and the CFD study was conducted using the URANS codes CFDSHIP-IOWA and Star-CCM+ plus the potential theory code AEGIR. Three speeds were covered and the wave conditions were chosen in order to study the ship’s response in waves under resonance and maximum exciting conditions. In the experiment, the heave and pitch motions and the resistance were measured together with wave elevation of the incoming wave. The model test was designed and conducted in order to enable UA assessment of the measured data. The results show that the ship responds strongly when the resonance and maximum exciting conditions are met. With respect to experimental uncertainty, the level for calm water is comparable to PMM uncertainties for maneuvering testing while the level is higher in waves. Concerning the CFD results, the computation shows a very complex and time-varying flow pattern. For the integral quantities, a comparison between EFD and CFD shows that the computed motions and resistance in calm water is in fair agreement with the measurement. In waves, the motions are still in fair agreement with measured data, but larger differences are observed for the resistance. The mean resistance is reasonable, but the first order amplitude of the resistance time history is underpredicted by CFD. Finally, it seems that the URANS codes are in closer agreement with the measurements compared to the potential theory.
145 citations
References
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TL;DR: In this article, a non-iterative method for handling the coupling of the implicitly discretised time-dependent fluid flow equations is described, based on the use of pressure and velocity as dependent variables and is hence applicable to both the compressible and incompressible versions of the transport equations.
4,019 citations
"Ship motions using single-phase lev..." refers methods in this paper
...This is the first step on the PISO [ 15 ] algorithm to enforce continuity....
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...A PISO [ 15 ] algorithm is used to obtain a pressure equation and satisfy continuity....
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Book•
01 Jan 1994
TL;DR: Modeling of Marine Vehicles Environmental Disturbances Stability and Control of Underwater Vehicles Dynamics and Stability of Ships Automatic Control of Ships Control of High-Speed Craft Appendices Bibliography Index as mentioned in this paper
Abstract: Modeling of Marine Vehicles Environmental Disturbances Stability and Control of Underwater Vehicles Dynamics and Stability of Ships Automatic Control of Ships Control of High--Speed Craft Appendices Bibliography Index
3,577 citations
"Ship motions using single-phase lev..." refers background or methods in this paper
...These relate to the time rate of change of the Euler angles by (see for instance [16])...
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...Under these conditions the rigid-body equations for ship-i can be written as [16]...
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TL;DR: This work presents a comprehensive approach to verification and validation methodology and procedures for CFD simulations from an already developed CFD code applied without requiring availability of the source code for specified objectives, geometry, conditions, and available benchmark information.
Abstract: We present a comprehensive approach to verification and validation methodology and procedures for CFD simulations from an already developed CFD code applied without requiring availability of the source code for specified objectives, geometry, conditions, and available benchmark information. Concepts, definitions, and equations derived for simulation errors and uncertainties provide the overall mathematical framework. Verification is defined as a process for assessing simulation numerical uncertainty and, when conditions permit, estimating the sign and magnitude of the numerical error itself and the uncertainty in that error estimate. The approach for estimating errors and uncertainties includes (1) the option of treating the numerical error as deterministic or stochastic, (2) the use of generalized Richardson extrapolation for J input parameters, and (3) the concept of correction factors based on analytical benchmarks, which provides a quantitative metric to determine proximity of the solutions to the asymptotic range, accounts for the effects of higher-order terms, and are used for defining and estimating errors and uncertainties
694 citations
"Ship motions using single-phase lev..." refers methods in this paper
...The procedures described in [24–26] were used to perform a verification analysis for the zeroth harmonic of the resistance, CT ;0....
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06 Jun 2005
195 citations
TL;DR: In this article, a single-phase level set method for unsteady viscous free surface flows is presented, where the location of the interface is determined using a signed distance function and appropriate interpolations at the fluid/fluid interface are used to enforce the jump conditions.
Abstract: : The single-phase level set method for unsteady viscous free surface flows is presented. In contrast to the standard level set method for incompressible flows, the single-phase level set method is concerned with the solution of the flow field in the water (or the denser) phase only. Some of the advantages of such an approach are that the interface remains sharp, the computation is performed within a fluid with uniform properties and that only minor computations are needed in the air. The location of the interface is determined using a signed distance function, and appropriate interpolations at the fluid/fluid interface are used to enforce the jump conditions. A reinitialization procedure has been developed for non-orthogonal grids with large aspect ratios. A convective extension is used to obtain the velocities at previous time-steps for the grid points in air, which allows a good estimation of the total derivatives. In this report we discuss the details of such implementations. The method was applied to three unsteady tests: a plane progressive wave, sloshing in a two-dimensional tank, and the wave diffraction problem in a surface ship, and the results compared against analytical solutions or experimental data. The method can in principle be applied to any problem in which the standard level-set method works, as long as the stress on the second phase can be specified (or neglected) and no bubbles appear in the flow during the computation.
178 citations
"Ship motions using single-phase lev..." refers background or methods in this paper
...An extension of the single-phase level set method presented in Carrica et al. [ 11 ] to treat object motions has been presented....
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...The mathematical and numerical models used in this paper for transient free surface problems have been discussed in detail in [ 11 ], and applied, verified and validated for transient ship flows [12] and steady-state problems [13]....
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...Once the time step is finished, a convective extension is done in air to assign the velocity and turbulence quantities in air for the current time step [ 11 ], and Eq. (27) solved inside the hole points to approximate variables in those regions....
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...At medium speed, the U-velocity contours of the boundary layer show a stronger bulging caused by the sonar dome than the similar case with the ship fixed [ 11 ]....
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...In the x–y plane, the grids are refined essentially uniformly to transport the incident waves from inlet to exit with a loss of amplitude of less than 1%, which is achieved if the wave is captured with at least 60 grid points per wavelength [ 11 ], a condition significantly exceeded in our grids....
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