This paper examines initial asymmetric wedge-impact flows with horizontal as well as vertical impact velocity. The method of two-dimensional vortex distributions is employed to model the initial-boundary-value problem. The numerical analysis involves discretization of the body surface and an iterative solution technique. Experimental drop tests of a prismatic wedge were performed to gain understanding and provide data for comparison of initial water impact when asymmetry and horizontal impact velocity are present. The experimental investigation of initial flow separation off the wedge vertex (i.e., keel) during impact is described. Initial separation-ventilation of the flow from the vertex due to asymmetric impact or horizontal-vertical impact velocity is examined in relation to the present theory. Agreement between the data and the numerical predictions was demonstrated for small degrees of asymmetry and small ratios of horizontal to vertical impact velocity. The initial flow detachment from the vertex also revealed interesting hydrodynamic characteristics.

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Initial water impact of a wedge at vertical and oblique angles

URANS studies of hydrodynamic performance and slamming loads on high-speed planing hulls in calm water and waves for deep and shallow conditions

An experimental study on water entry of asymmetric wedges

Hydrodynamic analysis techniques for high-speed planing hulls

The paper presents an overview of studies of slamming on ship structures. This work focuses on the hull slamming, which is one of the most important types of slamming problems to be considered in the ship design process and the assessment of the ship safety. There are three main research aspects related to the hull slamming phenomenon, a) where and how often a slamming event occurs, b) slamming load prediction and c) structural response due to slamming loads. The approaches used in each aspect are reviewed and commented, together with the presentation of some typical results. The methodology, which combines the seakeeping analysis and slamming load prediction, is discussed for the global analysis of the hull slamming of a ship in waves. Some physical phenomena during the slamming event are discussed also. Recommendations for the future research and developments are made.

Review of ship slamming loads and responses

The objective of this work is to continue to develop rationally based tools for hydrodynamic analysis of three-dimensional planing surfaces. The small craft naval architect is in need of a computationally efficient method to analyze planing surfaces allowing for sufficient sensitivity to hull geometric details. Planing surface analysis first received attention during the early part of the 20th century. This development was associated with flying boat applications. Von Karman (1929) and Wagner (1932) are considered the first researchers to develop rational models for planing surface analysis. The work contained herein is derived from the extension of Tulin (1957) originally by Vorus (1996) and later by Savander (1997). The model developed allows for general variation in deadrise in both the transverse and longitudinal directions. Hence, buttock line curvature is included in the formulation. The chine beam of the hull can vary longitudinally. Fundamental theoretical and numerical enhancements have been made to Vorus (1996) and Savander (1997). The current model is compared with constant and variable velocity 2-D impact experiments, prismatic planing model tests, Savitsky (1964) prismatic planing model, and deepwater Series 62 model test results (Clement & Blount 1963). The comparisons in many cases are excellent, especially at high Froude number. The comparisons illustrate the utility of the method. Problematic areas are presented and topics for further research are suggested.

Stephen M. Scorpio

Papers

Steady Hydrodynamic Analysis of Planing Surfaces