Two-Dimensional Impact Modelling with Three Degrees of Freedom and Its Application in the Dynamics of Planing Hulls

Roberto Algarín,Antonio Bula

doi:10.3390/app10031072

Abstract

Planing boat dynamics are a complex phenomenon and the maneuver forces acting on these kind of hulls are difficult to predict. In the current work, a mathematical model of a two-dimensional impact with three degrees of freedom (3DOF) is developed. The model was used to study wedge sections with knuckles, the vertical, horizontal, and rotational motion are considered. Pressure distribution, forces, and motion during the impact, considering both free fall and forced motion, are evaluated. The commercial CFD (Computational flow dynamics) software Star-CCM+ V9.06 was used to validate the formulation. Simulations with one, two, and three degrees of freedom were carried out, and the results were compared with CFD simulations, experimental data, and numerical solutions by others authors. The results show a good agreement with the authors. The model is extended to three dimensions applying slender body theory, and the forces in the hull are computed. The formulation allows evaluating the seakeeping with cross flow, dynamic stability, and manoeuvrability of planing boats with variable sections over the length.

Highlights

Planing boats are used in sports, tourism, and missions, such as patrol, rescue, and interdiction in rivers and seas
Wagner [2] developed a mathematical model based on potential flow; the model evaluates the pressure distribution on the symmetric impact without flow separation
0.4788wedge sections considering vertical developed by Wagner [2] and Toyama motion, horizontal motion, and rotation, while the flow separation from the knuckles was evaluated

Summary

Introduction

Planing boats are used in sports, tourism, and missions, such as patrol, rescue, and interdiction in rivers and seas. These boats can reach velocities near to 50 kn, and due to operational conditions, impact loads appear due to the waves, and vertical accelerations greater than 20 g can be attained [1]. Xu et al [5] extended the model developed by Vorus [4] for sections with asymmetrical entry and vertical velocity with flow separation. Xu et al [7] followed a procedure similar to Vorus [4], using potential flow and boundary elements theory to study the impact of asymmetric sections with vertical and horizontal velocity without flow separation

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Results

Conclusion