Water entry and exit of 2D and axisymmetric bodies

Water entry and exit of a body is an important topic in naval hydrodynamics as these phenomena play relevant roles both for offshore structures and vessels. Water entry and exit events are intrinsically transient and represent intense topological changes in the system, with large amounts of momentum exchange between phases. At its onset, they can be characterized by highly localized, both in space and time, loads on the vessel, influencing both the local structural safety of the structure and the global loads acting on it. The DualSPHysics code is proposed as a numerical tool for the simulation of fluid and floating object interaction. The numerical model is based on a Smoothed Particle Hydrodynamics discretization of the Navier-Stokes equations and Newton’s equations for rigid body dynamics. This paper examines the water impact, fluid motions, and movement of objects in the conventional case studies of object entry and exit from still water. A two dimensional body drop analysis was carried out demonstrating acceptable agreement of the movement of the object with published experimental and numerical results. The velocity field of the fluid is also captured and analyzed. Simulations for water entry and exit of a buoyant and neutral density cylinder compares well with previous experimental, numerical, and empirical studies in penetration, free surface evolution and object kinematics. These results provide a good foundation to evaluate the accuracy and stability of the DualSPHysics implementation for modeling the interaction between free surface flow and free moving floating objects.

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Water-entry and-exit of a horizontal circular cylinder

Applied Ocean Research ◽

10.1016/s0141-1187(88)80003-8 ◽

1988 ◽

Vol 10 (4) ◽

pp. 191-198 ◽

Cited By ~ 57

Author(s):

Martin Greenhow

Keyword(s):

Circular Cylinder ◽

Water Entry ◽

Entry And Exit ◽

Horizontal Circular Cylinder

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Oblique Water Entry and Exit of a Fully Ventilated Foil

10.21236/ada065007 ◽

1977 ◽

Cited By ~ 3

Author(s):

D. P. Wang

Keyword(s):

Water Entry ◽

Entry And Exit

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Oblique Water Entry and Exit of a Fully Ventilated Foil

Journal of Ship Research ◽

10.5957/jsr.1979.23.1.43 ◽

1979 ◽

Vol 23 (01) ◽

pp. 43-54 ◽

Cited By ~ 1

Author(s):

D. P. Wang

Keyword(s):

High Speed ◽

Horizontal Layer ◽

Water Entry ◽

Control Surface ◽

Entry And Exit ◽

Sea State ◽

Ratio Effect ◽

Present Solution ◽

Arbitrary Thickness ◽

Advance Ratio

The oblique entry of a two-dimensional, fully ventilated foil into a horizontal layer of water of arbitrary thickness is considered. When the thickness of the layer is finite, exit of the foil from the layer is studied. The present work is an extension of a previous one,2 in which only vertical entry and exit of the foil were considered. The consideration of oblique entry makes the present solution useful in studying not only the advance ratio effect on a partially submerged supercavitating propeller but also many other problems, such as the high-speed water entry and exit of a wing or a control surface, the operation of a high-speed hydrofoil in a high sea state. The results obtained in this work indicate that the force and moment coefficients of a foil decrease as the advance ratio is reduced.

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Turbulent fluid-structure interaction of water-entry/exit of a rotating circular cylinder using SPH method

International Journal of Modern Physics C ◽

10.1142/s0129183115500886 ◽

2015 ◽

Vol 26 (08) ◽

pp. 1550088 ◽

Cited By ~ 11

Author(s):

Jafar Ghazanfarian ◽

Roozbeh Saghatchi ◽

Mofid Gorji-Bandpy

Keyword(s):

Circular Cylinder ◽

Water Entry ◽

Numerical Code ◽

Navier Stokes ◽

Inertia Force ◽

Entry And Exit ◽

Sph Method ◽

Drag Forces ◽

Rotating Circular Cylinder ◽

Lift And Drag

This paper studies the two-dimensional (2D) water-entry and exit of a rotating circular cylinder using the Sub-Particle Scale (SPS) turbulence model of a Lagrangian particle-based Smoothed-Particle Hydrodynamics (SPH) method. The full Navier–Stokes (NS) equations along with the continuity have been solved as the governing equations of the problem. The accuracy of the numerical code is verified using the case of water-entry and exit of a nonrotating circular cylinder. The numerical simulations of water-entry and exit of the rotating circular cylinder are performed at Froude numbers of 2, 5, 8, and specific gravities of 0.25, 0.5, 0.75, 1, 1.75, rotating at the dimensionless rates of 0, 0.25, 0.5, 0.75. The effect of governing parameters and vortex shedding behind the cylinder on the trajectory curves, velocity components in the flow field, and the deformation of free surface for both cases have been investigated in detail. It is seen that the rotation has a great effect on the curvature of the trajectory path and velocity components in water-entry and exit cases due to the interaction of imposed lift and drag forces with the inertia force.

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