Experimental Investigation on the Role of Entrapped Air on Solitary Wave Forces on a Coastal Bridge Deck

2014 ◽  
Author(s):  
Betsy Seiffert ◽  
R. Cengiz Ertekin ◽  
Ian N. Robertson
Keyword(s):  
Solitary Wave ◽  
Water Surface ◽  
Wave Flow ◽  
Wave Forces ◽  
Qualitative Comparison ◽  
Wave Parameters ◽  
Bridge Model ◽  
Entrapped Air ◽  
Air Pockets ◽  
Uplift Forces

Recent devastations caused by tsunami and hurricanes and the inevitability of future hurricanes making landfall have focused attention on the need to assess the vulnerability of coastal structures, and bridges in particular. Findings from a series of experiments conducted on an 1:35 scale bridge model with girders under a solitary-wave flow are presented here. Side panels are added to the bridge model to trap air pockets between the girders. A range of elevations is considered, including cases where the bottom of the deck is just above the water surface and girders are submerged, to where girders are fully elevated above the water surface. Wave parameters tested include four water depths and five wave amplitudes. A qualitative comparison is made between results for forces on the trapped-air model and results from the same set of wave parameters on a model where the side panels are removed and air is allowed to escape. Results show effects of water particle velocity, buoyancy, air compression and sloshing all have effects on both horizontal forces in the direction of wave propagation and vertical uplift forces. In particular, in the case where air is trapped between girders and cannot escape, uplift forces are considerably larger when bridge elevation is such that the girders are fully elevated above the still water level or are slightly submerged.

Effect of Entrapped Air on Solitary Wave Forces on a Coastal Bridge Deck with Girders

2016 ◽  
Vol 21 (2) ◽  
pp. 04015036 ◽  
Author(s):  
Betsy R. Seiffert ◽  
R. Cengiz Ertekin ◽  
Ian N. Robertson
Keyword(s):  
Solitary Wave ◽  
Bridge Deck ◽  
Wave Forces ◽  
Entrapped Air

scholarly journals Solitary Wave Diffraction with a Single and Two Vertical Circular Cylinders

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zouhair Hafsia ◽  
Saliha Nouri ◽  
Salah Mahmoud Boulaaras ◽  
Ali Allahem ◽  
Salem Alkhalaf ◽  
...  
Keyword(s):  
Solitary Wave ◽  
Wave Diffraction ◽  
Present Model ◽  
Three Dimensional ◽  
Wave Generation ◽  
Transport Equations ◽  
Circular Cylinders ◽  
Wave Crest ◽  
Wave Flow ◽  
Wave Forces

This study investigates the three-dimensional (3-D) solitary wave interaction with two cylinders in tandem and side-by-side arrangements for two wave heights. The solitary wave generation and propagation are predicted using the volume of fluid method (VOF) coupled with the NavierStokes transport equations. The PHOENICS code is used to solve these transport equations. The solitary wave generation based on the source line developed by Hafsia et al. (2009) is extended in three-dimensional wave flow and is firstly validated for solitary waves propagating on a flat bottom. The comparison between numerical results and analytical solution for small wave height H / h = 0.1 and 0.2 shows good agreements. The wave crest and the pseudo-wavelength are well reproduced. Excellent agreements were found in terms of maximum run-up and wave forces by comparison with the present model and analytical studies. The present model can be tested for the extreme solitary wave to extend its application to a more realistic case study as the solitary wave diffraction with an offshore oil platform.

Detailed Study on Breaking Wave Interactions With a Jacket Structure Based on Experimental Investigations

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Jithin Jose ◽  
Olga Podrażka ◽  
Ove Tobias Gudmestad ◽  
Witold Cieślikiewicz
Keyword(s):  
Wind Turbines ◽  
Wave Breaking ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Wave Forces ◽  
Breaking Wave ◽  
Offshore Wind Turbines ◽  
Wave Parameters ◽  
Wave Slamming ◽  
Breaking Wave Forces

Wave breaking is one of the major concerns for offshore structures installed in shallow waters. Impulsive breaking wave forces sometimes govern the design of such structures, particularly in areas with a sloping sea bottom. Most of the existing offshore wind turbines were installed in shallow water regions. Among fixed-type support structures for offshore wind turbines, jacket structures have become popular in recent times as the water depth for fixed offshore wind structures increases. However, there are many uncertainties in estimating breaking wave forces on a jacket structure, as only a limited number of past studies have estimated these forces. Present study is based on the WaveSlam experiment carried out in 2013, in which a jacket structure of 1:8 scale was tested for several breaking wave conditions. The total and local wave slamming forces are obtained from the experimental measured forces, using two different filtering methods. The total wave slamming forces are filtered from the measured forces using the empirical mode decomposition (EMD) method, and local slamming forces are obtained by the frequency response function (FRF) method. From these results, the peak slamming forces and slamming coefficients on the jacket members are estimated. The breaking wave forces are found to be dependent on various breaking wave parameters such as breaking wave height, wave period, wave front asymmetry, and wave-breaking positions. These wave parameters are estimated from the wave gauge measurements taken during the experiment. The dependency of the wave slamming forces on these estimated wave parameters is also investigated.

scholarly journals IMPACT PRESSURES PRODUCED BY BREAKING WAVES

1974 ◽  
Vol 1 (14) ◽  
pp. 104 ◽  
Author(s):  
Norbert L. Ackerman ◽  
Ping-Ho Chen
Keyword(s):  
Water Surface ◽  
Ambient Pressure ◽  
Pressure Rise ◽  
Breaking Waves ◽  
Absolute Pressure ◽  
Maximum Pressure ◽  
Sound Waves ◽  
The Media ◽  
Entrapped Air ◽  
Entrained Air

Experiments were conducted in a vacuum tank in order to investigate the effect which entrained air has on impact loads which are produced when waves break upon a structure. In these experiments a flat plate was dropped onto a still water surface in an environment where the ambient pressure of the surrounding air could be controlled. Rings of varying height were fixed to the surface of the falling plate in order to trap different volumes of air between the falling plate and the water, Experimentally determined values were obtained of the maximum pressure pmax when the plate struck the water surface for various ring heights 6 and ambient pressures p0 in the vacuum tank. Experimental results indicate that the pressure rise or shock pressure Ps ~ (Pmax~Po) decreased with reductions in the ambient pressure and volume of entrapped air. Even when air was removed such that the absolute pressure in the tank was equal to the vapor pressure of the water, water hammer conditions, where the peak pressures depend upon the celerity of sound waves in the media, were never found to occur.

On the Cushioning of Water Impact by Entrapped Air

1968 ◽  
Vol 12 (02) ◽  
pp. 116-130 ◽  
Author(s):  
Grant Lewison ◽  
W. M. Maclean
Keyword(s):  
Free Surface ◽  
Flat Plate ◽  
Water Surface ◽  
Peak Pressure ◽  
Water Movement ◽  
Theoretical Work ◽  
Two Dimensional ◽  
Water Impact ◽  
Entrapped Air

Impact between a rigid flat plate and the free surface of water has been investigated experimentally and theoretically. Under two-dimensional conditions, the experiments give values of peak pressure of the same order as those recorded on ships slamming at sea, but very much smaller than would be expected from existing theories. New theoretical work is presented which takes account of the air trapped between the model and the water surface, and of both compressible and incompressible water movement. This shows good general agreement with the experiments, though further work is needed to confirm some of the assumptions made.

Innovative Approach for Use of Hydrofoils on Ultralight Seaplane

2020 ◽  
Author(s):  
Antonio Maglione ◽  
Ubaldo Cella ◽  
Marco E. Biancolini ◽  
Leonardo Lecce
Keyword(s):  
Life Cycle ◽  
Power Plant ◽  
Life Cycle Cost ◽  
Water Surface ◽  
Maintenance Cost ◽  
Wave Forces ◽  
Water Spray ◽  
Sea State ◽  
Important Benefit ◽  
Plant Maintenance

Retractable hydrofoils may enhance performances of seaplane during take-off and landing runs by lowering the speed when the hull is leaving or touching water surface. Hydrofoils are designed to complement airlift with additional hydrodynamic lift elevating the hull above the water at a speed lower than take-off speed; this minimizes slamming phenomenon on the hull, improving seakeeping capability of the seaplane, since water impacts are minimized compared to conventional configuration and, as a consequence, forces and accelerations on airframe, crew and passengers are reduced. This is of foremost importance on ultralight seaplanes, where wave forces acting on the relatively small aircraft mass provide high accelerations and significant roll, pitch and yaw forces that are higher on light aircraft compared to heavy seaplanes. As matter of facts, clear advantage of this configuration is the increase of sea state when a light seaplane can safely fly, providing additional useful days along the year. Important benefit is the improvement of seaplane performances during take-off and landing, reducing duration of the most critical flight phases, increasing overall safety and reducing pilot workload. Further benefits are envisioned, with optimization of wing, empennage and fuselage to minimize aero-drag and, as snow-ball effect, mission fuel consumption and energy power requirements. Life-cycle cost receives benefits too, since less water spray is ingested by engine and less water droplets impinge on fast revolving propeller, thus reducing expensive power plant maintenance cost over the entire service life.

Experimental Validation of Existing Numerical Models for the Interaction of Fluid Transients With In-Line Air Pockets

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Jane Alexander ◽  
Pedro J. Lee ◽  
Mark Davidson ◽  
Huan-Feng Duan ◽  
Zhao Li ◽  
...  
Keyword(s):  
Time Delay ◽  
Wave Speed ◽  
Numerical Models ◽  
Diagnostic Process ◽  
Air Pocket ◽  
Fluid Transients ◽  
Entrapped Air ◽  
Air Pockets ◽  
The Given ◽  
Potential Tool

Entrapped air in pipeline systems can compromise the operation of the system by blocking flow and raising pumping costs. Fluid transients are a potential tool for characterizing entrapped air pockets, and a numerical model which is able to accurately predict transient pressures for a given air volume represents an asset to the diagnostic process. This paper presents a detailed study on our current capability for modeling and predicting the dynamics of an inline air pocket, and is one of a series of articles within a broader context on air pocket dynamics. This paper presents an assessment of the accuracy of the variable wave speed and accumulator models for modeling air pockets. The variable wave speed model was found to be unstable for the given conditions, while the accumulator model is affected by amplitude and time-delay errors. The time-delay error could be partially overcome by combining the two models.

scholarly journals WAVE ACTION ON LARGE OFF-SHORE STRUCTURES

1976 ◽  
Vol 1 (15) ◽  
pp. 129 ◽  
Author(s):  
C.J. Apelt ◽  
A. Macknight
Keyword(s):  
Numerical Methods ◽  
Water Surface ◽  
Theoretical Method ◽  
Wave Force ◽  
Wave Action ◽  
Tidal Range ◽  
Scale Model ◽  
Wave Forces ◽  
Accurate Calculation ◽  
Scour Protection

The paper describes investigations carried out in order to design for the wave action, both wave force and scour, on large off-shore berthing structures sited approximately 1.3 miles (2.1 km) off-shore near Hay Point, North Queensland, in 56 feet (17 m) of water at low tide, the tidal range being 20 feet (6 m). The region is a cyclone area and the structures must be capable of withstanding attack from maximum predicted waves with period of 8.25 seconds and amplitude of 24 feet (7.3 m). The main units in the berthing structures are concrete caissons sunk on to the ocean bed and the largest of these have plan dimensions of approximately 150 feet (46.7 m) by 135 feet (41.4 m) with four columns approximately 40 feet (12.2 m) square projecting through the water surface. No theoretical method available at the time of the investigation was capable of accurate calculation of wave forces on these structures. A scale model was tested to obtain wave forces and the paper compares results from the model with those of numerical methods and discusses the application of the results to the design functions. Scour effects were also modelled and the results used as the basis for design of scour protection.

Experimental and numerical investigation of wave-current forces on coastal bridge superstructures with box girders

2019 ◽  
Vol 23 (7) ◽  
pp. 1438-1453 ◽  
Author(s):  
Jiawei Zhang ◽  
Bing Zhu ◽  
Azhen Kang ◽  
Ruitao Yin ◽  
Xin Li ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Numerical Models ◽  
Wave Forces ◽  
Vertical Force ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Coastal Bridges ◽  
Girder Bridges ◽  
Wave Parameters ◽  
Waves And Currents

Coastal bridges are exposed to hurricane waves and storm surges during hurricanes, which threaten the safety of the superstructures. Since waves and ocean currents coexist in the natural marine environment and the action of currents leads to changes in wave parameters and thus affects wave loads, considering their interaction is necessary for the study of wave forces on coastal bridges. In this study, hydrodynamic loads on a box girder with the joint action of regular waves and currents are investigated with both experiments and numerical models. A series of experiments of wave forces that include conditions with different wave heights, current velocities, wave periods and submergence depths are conducted in a wave flume. Two-dimensional numerical simulations are performed to further investigate the mechanics of wave-current forces on box girder bridges. The wave parameters and wave forces of the numerical simulations are compared with the experimental results. The results indicate that a following current usually leads to higher maximum horizontal forces and lower maximum vertical forces. The opposing current results in a higher maximum hydrodynamic vertical force than following current with a low submergence depth. However, due to the joint effect of the wave parameters and structure position relationships, the behaviours of wave forces in other situations become complicated. It is anticipated that this study can provide experimental data of wave-current forces for the superstructures of box girder bridges and enhance the understanding of the mechanism of bridge damage by waves and currents.

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