International Shipbuilding Progress - Volume 56, issue 1-2

Authors: Matveev, Konstantin I. | Ockfen, Alex E.

Article Type: Research Article

Abstract: A linear potential-flow method based on hydrodynamic point sources is developed for modeling steady hydrodynamics of hard-chine hulls. Source singularities are distributed on the wetted hull surface and on the free water surface. The wetted hull area is not known in advance and is found iteratively. The outcome of the model is the pressure distribution on the hull and the water surface elevations. Validation studies with two- and three-dimensional hull forms demonstrate good agreement for the lift coefficient and center of pressure in transitional and early planing regimes. The near-field wake wash reasonably agree with empirical data for wave profiles …behind a planing plate and for the trough position behind a submerged hydrofoil. The flexibility of the current method allows modeling of a variety of hull forms and systems with hydrodynamically interacting elements. Show more

Keywords: Planing hull, hydrofoil, CFD, hydrodynamic lift, wake wash

DOI: 10.3233/ISP-2009-0052

Citation: International Shipbuilding Progress, vol. 56, no. 1-2, pp. 1-13, 2009

Authors: Liqin, Liu | Yougang, Tang

Article Type: Research Article

Abstract: The problem of ship rolling in the stochastic wave has been studied in the past. In this paper the stochastic nonlinear dynamic behaviors including stochastic chaotic motion and probability density function of ship rolling are studied by nonlinear dynamic method and probability theory. The random Melnikov mean-square criterion is used to determine the parameter domain for ship's random chaotic motion. The probability density function of rolling response is evaluated in the chaotic parameter domain using path integral method. The time-dependent probability of ship rolling restricted within the safe domain is provided and capsizing is investigated in the probability's view.

Keywords: Stochastic nonlinear rolling, chaotic motion, random Melnikov mean-square criterion, probability density function

DOI: 10.3233/ISP-2009-0053

Citation: International Shipbuilding Progress, vol. 56, no. 1-2, pp. 15-27, 2009

Authors: Abdul Ghani, M.P. | Wilson, P.A.

Article Type: Research Article

DOI: 10.3233/ISP-2009-0054

Citation: International Shipbuilding Progress, vol. 56, no. 1-2, pp. 29-57, 2009

Authors: Shan, Ma | Wenyang, Duan

Article Type: Research Article

Abstract: A nonlinear time domain method is presented to calculate the vertical responses of fast ships. The extended 2.5D theory is used to evaluate nonlinear fluid radiation and diffraction forces which can take into account both the effects of the change of the underwater wet surface and the forward speed of a fast ship at free surface. A matched boundary integration equations algorithm is applied to solve the 2.5D theory in order to avoid numerical divergence observed when ships have large flare. The hydrostatic and Froude–Krylov forces are calculated below the incident wave elevation. The comparison of numerical results with model …test data shows that the numerical method can capture the main nonlinear effects and is valid for the calculation of vertical motions and wave loads of high speed ships. Show more

Keywords: Nonlinear wave induced loads, high speed vessels, 2.5D theory, numerical divergence, matched boundary integration equations

DOI: 10.3233/ISP-2009-0055

Citation: International Shipbuilding Progress, vol. 56, no. 1-2, pp. 59-93, 2009