A numerical study on water entry of cylindrical projectiles

2021 ◽  
Vol 33 (9) ◽  
pp. 093304
Author(s):  
Yanni Chang ◽  
Albert Y. Tong
Keyword(s):  
Numerical Study ◽  
Water Entry

scholarly journals Numerical Assessment of Similitude Parameters and Dimensional Analysis for Water Entry Problems

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Andrea L. Facci ◽  
Stefano Ubertini
Keyword(s):  
Numerical Study ◽  
Computational Study ◽  
Water Entry ◽  
Laboratory Scale ◽  
Analytical Models ◽  
Experimental Investigations ◽  
Two Dimensional ◽  
Wide Range ◽  
Entry Velocity ◽  
Real Size

The prediction of impulsive loads deriving from the sudden impact of a solid body on the water surface is of fundamental importance for a wide range of engineering applications. The study of hull-slamming phenomena largely relies on laboratory scale experimental investigations and on simplified analytical models. The aim of this paper is to quantitatively assess the interplay between the relevant nondimensional parameters for the water entry of a two-dimensional body, evidencing the similitude conditions that allow the transition from scaled experiments to real size applications. This assessment is performed through the numerical study of the hydrodynamics induced by the water impact of a two-dimensional wedge. The fluid flow is considered incompressible. First of all numerical simulations are validated by comparison with experimental data from the literature and with the Wagner seminal theory. Afterwards, a thorough computational study is performed by systematically varying all the relevant parameters, such as the nondimensional entry velocity and acceleration. We conclude by evidencing some design prescriptions that should be adopted in order to facilitate the transition of laboratory scale experiments to real scale applications.

Free Fall Water Entry of a Two-Dimensional Asymmetric Wedge in Oblique Slamming: A Numerical Study

2020 ◽  
Author(s):  
Saeed Hosseinzadeh ◽  
Mohammad Izadi ◽  
Kristjan Tabri
Keyword(s):  
Numerical Study ◽  
Experimental Studies ◽  
Free Fall ◽  
Water Entry ◽  
Vertical Acceleration ◽  
Two Dimensional ◽  
Pile Up ◽  
Real Phenomenon ◽  
Precise Simulation ◽  
Good Agreement

Abstract This paper examines the hydrodynamic problem of a two-dimensional symmetric and asymmetric wedge water entry through freefall motion. The gravity effect on the flow is considered and because of precise simulation close to the real phenomenon, the oblique slamming is analyzed. The defined problem is numerically studied using SIMPLE and HRIC schemes and by implementing an overset mesh approach. In order to evaluate the accuracy of the numerical model, the present results are compared and validated with previous experimental studies and showed good agreement. The results are presented and compared for each symmetry and asymmetry in different deadrise angles, drop heights and heel angles. Based on a comparison of the measured vertical acceleration of the experimental wedge data, it is determined that the proposed numerical method has relatively good accuracy in predicting the slamming phenomenon and wedge response. The influence of viscous regime on water entry simulations is investigated, in according to results, effect of viscosity is negligible. Results show that the heel angle dramatically affects the wedge dynamics, pile-up evolution, and pressure distribution. These results suggest evidence for a complex interaction between geometric parameters on the water entry of rigid wedges, which could finally develop our understanding of planing vessels operating in real sea conditions.

Numerical study on the deformation behaviors of elastic spheres during water entry

2020 ◽  
Vol 99 ◽  
pp. 103167
Author(s):  
Liu Yang ◽  
Yingjie Wei ◽  
Cong Wang ◽  
Weixue Xia ◽  
Jiachuan Li ◽  
...  
Keyword(s):  
Numerical Study ◽  
Water Entry ◽  
Deformation Behaviors

Numerical study on the cavity characteristics and impact loads of AUV water entry

2019 ◽  
Vol 89 ◽  
pp. 44-58 ◽  
Author(s):  
Yao Shi ◽  
Guang Pan ◽  
Guo-Xin Yan ◽  
Solomon C. Yim ◽  
Jun Jiang
Keyword(s):  
Numerical Study ◽  
Water Entry ◽  
Impact Loads ◽  
Cavity Characteristics

scholarly journals Cavity dynamics in water entry at low Froude numbers

2009 ◽  
Vol 641 ◽  
pp. 441-461 ◽  
Author(s):  
HONGMEI YAN ◽  
YUMING LIU ◽  
JAKUB KOMINIARCZUK ◽  
DICK K. P. YUE
Keyword(s):  
Free Surface ◽  
Asymptotic Theory ◽  
Numerical Study ◽  
Three Dimensional ◽  
Maximum Size ◽  
Water Entry ◽  
Boundary Integral ◽  
The Body ◽  
Gravitational Acceleration ◽  
Slender Body Theory

The dynamics of the air cavity created by vertical water entry of a three-dimensional body is investigated theoretically, computationally and experimentally. The study is focused in the range of relatively low Froude numbers, Fr ≡ V(gD)−1/2 ≤ O(10) (where V is the dropping velocity of the body, D its characteristic dimension and g the gravitational acceleration), when the inertia and gravity effects are comparable. To understand the physical processes involved in the evolution of cavity, we conduct laboratory experiments of water entry of freely dropping spheres. A matched asymptotic theory for the description of the cavity dynamics is developed based on the slender-body theory in the context of potential flow. Direct comparisons with experimental data show that the asymptotic theory properly captures the key physical effects involved in the development of the cavity, and in particular gives a reasonable prediction of the maximum size of the cavity and the time of cavity closure. Due to the inherent assumption in the asymptotic theory, it is incapable of accurately predicting the flow details near the free surface and the body, where nonlinear free surface and body boundary effects are important. To complement the asymptotic theory, a fully nonlinear numerical study using an axisymmetric boundary integral equation is performed. The numerically obtained dependencies of the cavity height and closure time on Froude number and body geometry are in excellent agreement with available experiments.

A numerical study on nested cavities during the water entry of deformable elastic spheres

2021 ◽  
pp. 103773
Author(s):  
Liu Yang ◽  
Yingjie Wei ◽  
Cong Wang ◽  
Weixue Xia ◽  
Yuanyuan Li
Keyword(s):  
Numerical Study ◽  
Water Entry

Two-Dimensional Unsteady Planing

1996 ◽  
Vol 40 (03) ◽  
pp. 200-210 ◽  
Author(s):  
Tore Ulstein ◽  
Odd M. Faltinsen
Keyword(s):  
Numerical Study ◽  
Leading Edge ◽  
Length Change ◽  
Present Theory ◽  
Water Entry ◽  
Time Varying ◽  
Two Dimensional ◽  
Hydrodynamic Problem ◽  
Square Root Singularity ◽  
The Time Domain

An analytical and numerical study of two-dimensional unsteady planing of a flat plate is presented. The immersion of the plate is assumed small; hence, the spray at the leading edge is represented by a square root singularity. The analogy to airfoil theory is used and the hydrodynamic problem is solved in the time domain. The time-varying wetted-length change due to the water flow is accounted for by a generalized Wagner approach. The present theory is verified by comparison with an analytical solution by Sedov (1940) for water entry of a planing plate and with the linear frequency domain solution by Bessho & Komatsu (1984) for a heaving planing plate.

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