scholarly journals WAVE STRUCTURE INTERACTION: ROLE OF ENTRAPPED AIR ON WAVE IMPACT AND UPLIFT FORCES

2011 ◽  
Vol 1 (32) ◽  
pp. 57 ◽  
Author(s):  
Mehrdad Bozorgnia ◽  
Jiin-Jen Lee ◽  
Frederic Raichlen
Keyword(s):  
Free Surface ◽  
Hurricane Katrina ◽  
Hydrodynamic Forces ◽  
Wave Load ◽  
Wave Impact ◽  
Two Phase ◽  
Bridge Superstructure ◽  
Entrapped Air ◽  
Uplift Forces

In present paper, a numerical wave load model based on compressible two-phase Navier Stokes type equations is used to evaluate hydrodynamic forces exerted on I-10 bridge across Mobil Bay which was extensively damaged during Hurricane Katrina. The volume of fluid method (VOF) is used in the model to describe dynamic free surface which is capable of simulating complex discontinuous free surface associated with wave-deck interactions. Special emphasis was put on investigating the role of entrapped air on hydrodynamic forces exerted on bridge superstructure. Numerical simulation results indicate that air entrapment can significantly amplify uplift forces applied to the bridge superstructure. To mitigate hydrodynamic forces, effectiveness of airvents is investigated. It has been shown that airvents can significantly damp out wave energy and can effectively reduce uplift forces.

scholarly journals Numerical Modeling and Simulation of Wave Impact of a Circular Cylinder during the Submergence Process

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Xiaozhou Hu ◽  
Yiyao Jiang ◽  
Daojun Cai
Keyword(s):  
Free Surface ◽  
Circular Cylinder ◽  
Ocean Waves ◽  
Navier Stokes ◽  
Wave Load ◽  
Wave Impact ◽  
Rans Equations ◽  
Wave Slamming ◽  
Surface Profiles ◽  
Numerical Wave

Wave slamming loads on a circular cylinder during water entry and the subsequence submergence process are predicted based on a numerical wave load model. The wave impact problems are analyzed by solving Reynolds-Averaged Navier-Stokes (RANS) equations and VOF equations. A finite volume approach (FV) is employed to implement the discretization of the RANS equations. A two-dimensional numerical wave tank is established to simulate regular ocean waves. The wave slamming problems are investigated by deploying a circular cylinder into waves with a constant vertical velocity. The present numerical method is validated using other numerical or theoretical results in accordance with varying free surface profiles when a circular cylinder sinks in calm water. A numerical example is given to show the submergence process of the circular cylinder in waves, and both free surface profiles and the pressure distributions on the cylinder of different time instants are obtained. Time histories of hydrodynamic load on the cylinder during the submergence process for different wave impact angles, wave heights, and wave periods are obtained, and results are analyzed in detail.

Numerical Investigation of Tsunami-Like Solitary Wave Interaction with a Seawall

2017 ◽  
Vol 11 (01) ◽  
pp. 1740006 ◽  
Author(s):  
Changbo Jiang ◽  
Xiaojian Liu ◽  
Yu Yao ◽  
Bin Deng ◽  
Jie Chen
Keyword(s):  
Free Surface ◽  
Solitary Waves ◽  
Stokes Equations ◽  
Dynamic Pressure ◽  
Laboratory Data ◽  
Three Dimensional ◽  
Wave Interaction ◽  
Surface Velocity ◽  
Wave Impact ◽  
Two Phase

Seawall is a most commonly used structure in coastal areas to protect the landscape and coastal facilities. The studies of interactions between the tsunami-like solitary waves and the seawalls are relatively rare in the literature. In this study, a three-dimensional numerical model based on OpenFOAM® was developed to investigate the tsunami-like solitary waves propagating over a rectangular seawall. The Navier–Stokes equations for two-phase incompressible flow, combining with methods of [Formula: see text] for turbulence closure and Volume of Fluid (VOF) for tracking the free surface, were solved. Laboratory experiments were performed to measure some of the hydrodynamic feature associated with solitary waves. The model was then validated by the laboratory data, and good agreements were found for free surface, velocity and dynamic pressure around the seawall. Finally, a series of numerical experiments were conducted to analyze the evolution of both wave and flow fields, the overtopping discharge as well as wave pressure (force) around the seawall, special attention is given to the effects of seawall crest width. Our findings will help to improve the understanding in the occurrences of tsunami-induced damages in the vicinity of seawall such as wave impact and local scouring.

Study of an Entrapped Air Pocket due to Sloshing Using Experiments and Numerical Simulations

2017 ◽  
Author(s):  
Reza Firoozkoohi ◽  
Bjørn Christian Abrahamsen ◽  
Odd Magnus Faltinsen
Keyword(s):  
Free Surface ◽  
Test Case ◽  
Two Phase ◽  
Mixture Flow ◽  
Flow Solver ◽  
Air Pocket ◽  
Spring System ◽  
Phase Mixture ◽  
Entrapped Air ◽  
Mass Spring

The capability of the OpenFoam software to model slamming where air is entrapped between the free surface and the structure is investigated. The test case studied is a previously studied phenomenon, where an air pocket is entrapped between the free surface and the upper corner of a rectangular tank during sloshing. The air is entrapped due to the shape of the wave approaching the roof. The air pocket is compressed and starts to oscillate. The oscillations resemble the free oscillations of a mass spring system. OpenFoam results are compared with experiments and a numerical method based on a boundary element method (BEM) both of which are available from the previous study. In this work a compressible VOF (Volume Of Fluid) Eulerian two-phase mixture flow solver called compressible InterFoam from OpenFOAM package is used to perform the simulations. The sensitivity of the results to numerical parameters is addressed.

Simulation of Wave Impact With Compressible Air Entrainment Based on Consistent Particle Method

2015 ◽  
Author(s):  
C. G. Koh ◽  
M. Luo ◽  
W. Bai ◽  
M. Gao
Keyword(s):  
Sound Speed ◽  
Incompressible Flows ◽  
Particle Method ◽  
Air Entrainment ◽  
Ideal Gas ◽  
Wave Impact ◽  
Two Phase ◽  
Primitive Form ◽  
Entrapped Air ◽  
Predictor Corrector

A numerical strategy for incompressible-compressible two-phase flows with large density difference is presented. The incompressible phase is modeled by the recently developed 2-phase Consistent Particle Method (2P-CPM) for incompressible flows. For the compressible phase, a thermodynamically-consistent compressible solver is developed by using the ideal gas equation of state (EOS). Since sound speed is not explicitly involved, this compressible solver can overcome the issues in the determination of numerical sound speed. In addition, the compressible solver can be integrated with the incompressible 2P-CPM seamlessly because they both use a predictor-corrector scheme to solve the governing equation of primitive form. The benchmark example of dam break with entrapped air pocket is studied to demonstrate the accuracy of the proposed method.

scholarly journals Nonlinear Simulation of Wave Train Impact on a Vertical Seawall

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 986 ◽  
Author(s):  
Dezhi Ning ◽  
Xiang Li ◽  
Chongwei Zhang
Keyword(s):  
Free Surface ◽  
Wave Train ◽  
Wave Load ◽  
Wave Impact ◽  
Nonlinear Simulation ◽  
Irregular Wave ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Free Surface Oscillations ◽  
Run Up

A 2D nonlinear numerical wave flume is developed to investigate the wave train impact on a vertical seawall. Fully nonlinear kinematic and dynamic boundary conditions are satisfied on the instantaneous free surface. Cases of single-, double- and multi-crest wave trains are discussed. For single-crest wave train cases, the present nonlinear results are compared with the solution of the Serre-Green-Naghdi (SGN) model, showing good agreement. For double-crest wave train cases, the SGN model underestimates the maximum wave run-up along the vertical seawall. Compared with the linear results, the nonlinearity for double-crest cases can lead to an evident increase of the wave run-up and high-frequency free-surface oscillations. Through a fast Fourier analysis, evident nonlinear characteristics of the time series of the wave run-up and wave load during the wave impact process are confirmed. For multi-crest wave train cases, irregular wave run-ups can be observed. In some cases, the wave run-up along the vertical seawall can reach about 6 times that of the incident wave, which should be considered carefully in a practical design.

On the role of tin underlays for the prevention of thermal grooving in thin gold films

1986 ◽  
Vol 44 ◽  
pp. 732-733
Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff
Keyword(s):  
Thin Film ◽  
Free Surface ◽  
Grain Boundary ◽  
Beneficial Effect ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Distinct Advantage ◽  
Gold Films ◽  
Gold Thin Film

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.

scholarly journals The role of interfaces on dynamic damage in two phase metals

2012 ◽  
Author(s):  
Ellen Cerreta ◽  
Saryu Fensin ◽  
Juan P. Escobedo ◽  
George Thompson Gray III ◽  
Adam Farrow ◽  
...  
Keyword(s):  
Two Phase ◽  
Dynamic Damage

A Study on Development of the Performance Analysis Method of the Floating OWC-WEC Using the MPS Method

2015 ◽  
Author(s):  
Yutaro Sasahara ◽  
Mitsuhiro Masuda ◽  
Kiyokazu Minami
Keyword(s):  
Wave Energy ◽  
Two Phase Flow ◽  
Wave Energy Converter ◽  
Response Analysis ◽  
Phase Flow ◽  
Energy Converter ◽  
Wave Impact ◽  
Two Phase ◽  
Mps Method ◽  
Type Wave

When concrete examination towards utilization is needed, it is necessary to estimate the safety and the performance of a floating Oscillation Water Column (OWC)-type wave energy converter under abnormal oceanographic phenomenon such as large waves, wave impact force, deck wetness and complex motion of mooring system. Therefore, to choose a proper numerical method is important. This present paper describes a fundamental study about estimation of safety and performance of floating OWC-type wave energy converter using the two-phase flow MPS method. In this research, firstly, new algorithm is installed in order to solve problems of the two-phase flow MPS method. Secondly, applicability to an response analysis of a wharf installation type OWC-WEC of the improved MPS method is examined by wave pressure acting to the OWC-WEC and response in the air chamber of the OWC-WEC.

Microstructure of Polycrystalline MgO Penetrated by a Silicate Liquid

1996 ◽  
Vol 2 (3) ◽  
pp. 113-128 ◽  
Author(s):  
Sundar Ramamurthy ◽  
Michael P. Mallamaci ◽  
Catherine M. Zimmerman ◽  
C. Barry Carter ◽  
Peter R. Duncombe ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Grain Growth ◽  
Glassy Phase ◽  
Silicate Liquid ◽  
Two Phase ◽  
The Matrix ◽  
Devitrification Process ◽  
Phase Mixture

Dense, polycrystalline MgO was infiltrated with monticellite (CaMgSiO4) liquid to study the penetration of liquid along the grain boundaries of MgO. Grain growth was found to be restricted with increasing amounts of liquid. The inter-granular regions were generally found to be comprised of a two-phase mixture: crystalline monticellite and a glassy phase rich in the impurities present in the starting MgO material. MgO grains act as seeding agents for the crystallization of monticellite. The location and composition of the glassy phase with respect to the MgO grains emphasizes the role of intergranular liquid during the devitrification process in “snowplowing” impurities present in the matrix.

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