Numerical predictions of ship motions at high forward speed

Faltinsen, Odd M.; Zhao, Rui

doi:10.1098/rsta.1991.0011

Cited by 72 publications

(9 citation statements)

References 2 publications

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“…One can verify that, however, the last condition in Equation (10) for G 1_∞ is not the same as the inviscid one given in Equation (11). Thus, we need to design an appropriate G 1_∞ (p, q; ) that satisfy all conditions in Equations (10).…”

Section: Instantaneous Term Of Tgf 1 _v ∞mentioning

confidence: 99%

“…Without loss of generality, the proposed TGF 1 _V ∞ are limited to the two-dimensional (2D) flows with infinite depth, which have never been studied in literature. In fact, the 2D TGF_V are able to evaluate the viscous dissipation effects on hydrodynamics not only of 2D zero-speed floating bodies, but also of 3D high-speed ships within the 2.5D or 2D + t framework [11]. Moreover, the approach provided here for developing the 2D TGF 1 _V ∞ can also be employed for developing other types of GF_V ∞ .…”

Section: Introductionmentioning

confidence: 99%

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A Time-Domain Green’s Function for Interaction between Water Waves and Floating Bodies with Viscous Dissipation Effects

Guo

Qin

2018

Water

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Abstract:A novel time-domain Green's function is developed for dealing with two-dimensional interaction between water waves and floating bodies with considering viscous dissipation effects based on the "fairly perfect fluid" model. In the Green's function, the temporal (lower order viscosity coefficient term) and spatial (higher order viscosity coefficient term) viscous dissipation effects are fully considered. As compared to the methods based on the existing time-domain Green's functions that could not account for the spatial viscous dissipation, the method based on the new time-domain Green's function can give much better numerical results and overcome instability problems related to the existing Green's function, according to the numerical tests and comparison with CFD modeling data for a few cases related to floating bodies with a flare angle.

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Section: Instantaneous Term Of Tgf 1 _v ∞mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Time-Domain Green’s Function for Interaction between Water Waves and Floating Bodies with Viscous Dissipation Effects

Guo

Qin

2018

Water

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“…Governing equations and boundary conditions for ship motion analysis based on 2.5D theory have been presented in many studies. Faltinsen and Zhao (1991) addressed a possible expression for 2.5D theory in simulating ship motions. The formulations are summarized as 2 2 2 2 0, …”

Section: The 25d Theory For Ship Hydrodynamicsmentioning

confidence: 99%

A predictive controller for joint pitch-roll stabilization

Duan

Han

Wang³

et al. 2016

J. Zhejiang Univ. Sci. A

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Abstract:Reduction of roll and pitch motions is critical in improving the safety and operability of a ship. In this paper, a predictive controller for a ship equipped with two pairs of active fins is proposed for joint pitch-roll stabilization. The proposed controller is developed on the basis of ship motion and hydrodynamic force prediction (SMHFP). The SMHFP controller consists of a short-term predictor, a force estimator, and a fin angle allocator. The short-term predictor adopts an autoregressive (AR) approach and serves to forecast ship motions. Then, predicted ship motions are used in an external hydrodynamic force estimator to evaluate the expected stabilizing forces. Finally, the optimal attack angles for active fins are allocated based on external hydrodynamic forces forecasts. The control system of the stabilizing fins and SMHFP controller is integrated into the sea-keeping program. The program was developed based on a weakly nonlinear 2.5D method, which shows better efficiency and accuracy compared with conventional 2D and 3D methods. To evaluate the performance of the proposed controller, numerical simulations of the joint pitch-roll stabilization under various sea states were investigated on a ship model. The results suggest that the SMHFP controller shows satisfactory performance in reducing pitch and roll motions simultaneously.

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“…In this paper, the multi-domain concept is first incorporated into the 2.5D (two and a half dimensional) method [12,13] based on the time domain free surface Green's function with viscous dissipation effects [14] to form a multi-domain 2.5D method. The 2.5D method is a high-speed slender body method that could be able to predict the hydrodynamics of high-speed ships such as SES.…”

Section: Introductionmentioning

confidence: 99%

Multi-Domain 2.5D Method for Multiple Water Level Hydrodynamics

Guo

Qin

2018

Water

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Abstract:The mean water surface (interface) under the air cushion of a surface effect ship (SES) or an air cushion supported platform (ACSP) is generally lower than the outside water surface due to the overpressure of the air cushion. To precisely analyze the hydrodynamics under the air cushion, multiple water levels should be considered in numerical models. However, when using free surface Green's functions as numerical methods, the water level difference cannot be taken into account, because free surface Green's functions normally require users to set in the whole water domain a unique datum water surface that completely separates the air domain and the water domain. To overcome this difficulty, a multi-domain approach is incorporated into a 2.5D method that is based on a time domain free surface Green's function with viscous dissipation effects in this paper. In the novel multi-domain 2.5D method, the water domain is partitioned into inner and outer domains, and the interface is located in the inner domain while the outside water surface is placed in the outer domain. In each domain there exists only one unique water level, while water levels in different domains are allowed to be different. Benefited from this characteristic, the multi-domain 2.5D method is able to precisely consider the water level difference and its influence on hydrodynamics. The newly proposed multi-domain 2.5D method is employed to predict the hydrodynamics of an SES, and it is confirmed that the multi-domain 2.5D method can give better numerical results than the single-domain one for the given case.

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Numerical predictions of ship motions at high forward speed

Abstract: A theory for ship motions at high forward speed is presented. The theory includes interaction between the steady and unsteady flow field. Numerical results for the steady flow and added mass and damping are compared with experimental results.

Cited by 72 publications

References 2 publications

A Time-Domain Green’s Function for Interaction between Water Waves and Floating Bodies with Viscous Dissipation Effects

A Time-Domain Green’s Function for Interaction between Water Waves and Floating Bodies with Viscous Dissipation Effects

A predictive controller for joint pitch-roll stabilization

Multi-Domain 2.5D Method for Multiple Water Level Hydrodynamics

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