Numerical Study of Evolution of Air Pockets during Water Impact of a Flat-Bottom Structure

2017 ◽  
Author(s):  
Qiulin Qu ◽  
Gaohe Ji ◽  
Peiqing Liu ◽  
Xueliang Wu ◽  
Ramesh K. Agarwal
Keyword(s):  
Numerical Study ◽  
Water Impact ◽  
Flat Bottom ◽  
Air Pockets

Multiphysics Study of Structural Impact to Fluidic Media

2011 ◽  
Vol 673 ◽  
pp. 1-10 ◽  
Author(s):  
Matej Vesenjak ◽  
Zoran Ren ◽  
Mojtaba Moatamedi
Keyword(s):  
Impact Loading ◽  
Numerical Study ◽  
Fluid Structure Interaction ◽  
Water Impact ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Particle Hydrodynamics ◽  
Ale Methods ◽  
Smoothed Particle ◽  
Space Capsule

The paper presents a fluid structure interaction based numerical study of impact loading for a hemispherical structure upon water and a space capsule water landing. The study has a strong relevance in the determination of the crashworthiness of aerospace structures upon water impact loading. Finite element based numerical techniques have been used for the analysis of the underlying transient dynamic and fluid-structure interaction. Smoothed Particle Hydrodynamics (SPH) and Arbitrary Lagrange-Eulerian (ALE) methods have been used to simulate the behaviour of the fluid (water) under impact conditions. The accelerations and velocities of the impacting objects have been validated with by experimental measurements and analytical results. Numerical analyses showed a strong potential for the use of developed computational fluid structure interaction models for analyses of water impact loading related problems.

A Numerical Study of Uplift Motion of Flat-Bottom Cylindrical Shell Model Tank Subjected to Harmonic Excitation

2010 ◽  
Author(s):  
Teruhiro Nakashima ◽  
Tomoyo Taniguchi
Keyword(s):  
Cylindrical Shell ◽  
Numerical Study ◽  
Harmonic Excitation ◽  
Fe Analysis ◽  
Experimental Result ◽  
Bottom Plate ◽  
Flat Bottom ◽  
Tank Model ◽  
Rocking Motion ◽  
The Impact

In analyzing the rocking motion of unanchored flat-bottom cylindrical shell tanks, the fluid-structure interaction and the impact between the tank bottom plate and tank foundation should be treated adequately. Employing harmonic excitation, this paper examines the applicability of the explicit FE-Analysis technique for analyzing the rocking motion of a flat-bottom cylindrical shell tank model. Since the tank model possesses a thick and elastic bottom plate, the model tank pivots upon from an edge of the bottom plate to another edge of that reciprocally. The rocking motion of the model tank to the harmonic excitation is numerically computed and the uplift displacement of the tank is compared with experimental result. Agreement between the numerical and experimental results implies that the explicit FE-Analysis is capable of analyzing the rocking motion of cylindrical shell tanks subjected to the earthquake excitation.

Experimental and Numerical Study of the Slow-Drift Motion of a Rectangular Barge Moored at an Inclined Beach

2010 ◽  
Author(s):  
Bernard Molin ◽  
Fabien Remy ◽  
Yanan Liu ◽  
Marie-Christine Rouault
Keyword(s):  
Numerical Study ◽  
Scale Model ◽  
Sea State ◽  
Flat Bottom ◽  
Drift Motion ◽  
Beam Seas ◽  
Slow Drift ◽  
Irregular Beam Seas ◽  
Sway Motion ◽  
Slow Drift Motion

An experimental campaign is reported on the slow-drift motion of a rectangular barge moored in irregular beam seas. The 24 m long false bottom of the basin is raised and inclined at a slope of 5%, from 1.05 m below the free surface to 0.15 m above. The barge is moored successively at 4 different locations, in water-depths ranging from 54 to 21 cm. The measured slow-drift component of the sway motion is compared with state-of-the-art calculations based on Newman approximation. At 54 cm depth good agreement is obtained between calculations and measurements. At 21 cm depth the Newman calculation exceeds the measured value. When the flat bottom setdown contribution is added up, the calculated value is 2 to 3 times larger than the measured one. A second-order model is proposed to account for the shoaling of a bichromatic sea-state propagating in decreasing water-depth. Application of this numerical model to the scale-model tests shows that in shoaling conditions the setdown contribution to the slow-drift excitation can counteract and not necessarily add up to the Newman component.

scholarly journals Numerical Study on the Commissioning Charge-Up Process of Horizontal Pipeline with Entrapped Air Pockets

2014 ◽  
Vol 6 ◽  
pp. 838926 ◽  
Author(s):  
Xinyu Zhang ◽  
Bo Yu ◽  
Yan Wang ◽  
Jianyu Xie ◽  
Dongping Qiu ◽  
...  
Keyword(s):  
Process Design ◽  
Pressure Field ◽  
Numerical Study ◽  
Critical Parameters ◽  
Hydraulic Characteristics ◽  
Oil Pipeline ◽  
Air Pocket ◽  
Acute Change ◽  
Entrapped Air ◽  
Air Pockets

Accurately predicting hydraulic characteristics in the charge-up process of horizontal pipeline with entrapped air pocket is of great significance for the process design and field operation of the oil pipeline commissioning. In this paper, this process is simulated and its hydraulic characteristics are analyzed. Finite difference method and characteristic method are combined to obtain the velocity and pressure field of the whole line. Results show that when air pockets reach the outlet of the pipeline, they blow out tempestuously and the velocity of gas may reach tens times of its normal flow velocity. At the beginning and end of the blowing out, velocity and pressure of the whole line suffer acute change. Based on this, the influence of several critical parameters is compared and analyzed by several groups of examples.

Numerical Study of Water Impact of an Elastic Cylindrical Shell

AIAA Journal ◽  
2016 ◽  
Vol 54 (10) ◽  
pp. 3296-3303 ◽  
Author(s):  
Qiulin Qu ◽  
Rui Wang ◽  
Hao Guo ◽  
Peiqing Liu ◽  
Ramesh K. Agarwal
Keyword(s):  
Cylindrical Shell ◽  
Numerical Study ◽  
Elastic Cylindrical Shell ◽  
Water Impact

scholarly journals Development of the Physics–Based Morphology Model as the Platform for the Optimal Design of Beach Nourishment Project: A Numerical Study

2020 ◽  
Vol 8 (10) ◽  
pp. 828
Author(s):  
Yong Jun Cho
Keyword(s):  
Numerical Simulation ◽  
Optimal Design ◽  
Numerical Study ◽  
Beach Nourishment ◽  
Suspended Load ◽  
Stokes Drift ◽  
Physical Model Test ◽  
Surface Boundary ◽  
Flat Bottom ◽  
Morphology Model

In this study, a physics-based morphology model is developed and to test the feasibility of the morphology model proposed in this study as the platform for the optimal design of the beach nourishment project, the beach restoration process by the infra-gravity waves underlying the swells in a mild sea is numerically simulated. As a hydrodynamic module, the IHFOAM wave toolbox having its roots in the OpenFoam is used. Speaking of the morphology model, a transport equation for suspended load and the Exner type equation constitute the morphology model. In doing so, the probability theory first introduced by Einstein and the physical model test by Bagnold are used as the constituent sub-model of the morphology model. Numerical results show that among many flow features that are indispensable in forming sand bars over the flat bottom and swash zone, the partially skewed and asymmetric bottom shearing stresses, a shoreward Stokes drift near the free surface, boundary layer streaming near the seabed, and undertow toward the offshore were successfully simulated using the morphology model proposed in this study. It was also shown that plunging type breaker occurring at the final stage of the shoaling process, and its accompanying second breaker, sediment entrainment at the seabed, and the redistribution of suspended load by the down rush of preceding waves were successfully reproduced in the numerical simulation, and agreements with our experience in the field were very encouraging. In particular, the sand bar formation process over the flat bottom and backshore were successfully reproduced in the numerical simulation, which has been regarded as a challenging task.

A Simplified Method of Water Impact on Elastic Plate in Early Stage

2016 ◽  
Author(s):  
Hua Sun ◽  
Deyu Wang
Keyword(s):  
Elastic Plate ◽  
Early Stage ◽  
Impact Loads ◽  
Arbitrary Lagrangian Eulerian ◽  
Water Impact ◽  
Flat Bottom ◽  
Initial Stage ◽  
Simplified Method ◽  
Bottom Structures ◽  
The Impact

For most flat-bottom marine structures, the impact loads are generated by complex transient coupling effects of solid, air and water. However, there are rare simplified forecasting methods to obtain the impact loads and dynamic response of the flat-bottom structures by considering both hydro elastic and air cushion effects. In the paper, a new simplified analysis method of water impact on the elastic plate is proposed referred to Verhagen’s model of the rigid plate. The analysis is focused on the initial stage during which the highest hydrodynamic loads are generated. The method simulates the interaction between the plate, the air and the water. Also, fluid-structure coupling results from the simplified method are compared to numerical results from Arbitrary Lagrangian–Eulerian method and experimental results to validate the feasibility and accuracy of this simplified method.

scholarly journals A NUMERICAL STUDY OF THE IMPORTANCE OF NONLINEAR EFFECTS FOR FABRY-PEROT RESONANCE OF WATER WAVES

2018 ◽  
pp. 26
Author(s):  
Michel Benoit ◽  
Jie Zhang
Keyword(s):  
Water Waves ◽  
Numerical Study ◽  
Wave Train ◽  
Nonlinear Effects ◽  
Wave Theory ◽  
Resonance Phenomenon ◽  
Linear Wave ◽  
Flat Bottom ◽  
Fabry Perot ◽  
Incident Waves

When a regular wave train propagates over a patch of periodic bottom corrugations on an otherwise flat bottom (with still water depth h), the so called Bragg resonance phenomenon can appear, leading to a significant reflection of the incident waves due to the presence of the ripple patch. This effect is maximum when the wavelength of the surface waves (noted A = 2n/k) is twice that of the bottom ripples (noted Ab = 2n/kb). This phenomenon has been studied both experimentally (e.g. Davies & Heathershaw, 1984) and theoretically within the linear wave theory framework (e.g. Mei, 1985; Dalrymple & Kirby, 1986).

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