scholarly journals HYDRODYNAMIC LOAD ON THE BUILDING CAUSED BY OVERTOPPING WAVES

2012 ◽  
Vol 1 (33) ◽  
pp. 59 ◽  
Author(s):  
Xuexue Chen ◽  
Wael Hassan ◽  
Wim Uijttewaal ◽  
Toon Verwaest ◽  
Henk Jan Verhagen ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Vertical Wall ◽  
Scale Model ◽  
Hydrodynamic Load ◽  
Empirical Formulas ◽  
Geometrical Characteristics ◽  
Wave Parameters ◽  
Model Research ◽  
Physical Scale ◽  
To Come

Wide crested dike can reduce the kinetic energy of the overtopping wave and make the overtopping wave to flow back to the seaside. If a coastal town were built on or near a dike, the overtopping wave running on the dike crest generates the force which can affect the buildings located in its path. However, quantifying the hydrodynamic load on the building caused by overtopping waves is not straightforward because little empirical formulas are given in literature for this kind of configuration. Therefore, physical scale model research was carried out. The purpose of this research is to come up with a relationship describing the force on a vertical wall exerted by the overtopping wave as a function of wave parameters and geometrical characteristics.

scholarly journals WAVES OVERTOPPING A WIDE-CRESTED DIKE

2011 ◽  
Vol 1 (32) ◽  
pp. 7 ◽  
Author(s):  
Toon Verwaest ◽  
Philippe Vanpoucke ◽  
Marc Willems ◽  
Tom De Mulder
Keyword(s):  
Theoretical Model ◽  
Energy Balance ◽  
Kinetic Energy ◽  
Scale Model ◽  
Coastal Protection ◽  
Model Concept ◽  
Wave Overtopping ◽  
Model Research ◽  
Physical Scale ◽  
Semi Empirical

If a coastal dike has a crest width of more than say a few meters, then wave overtopping will be significantly reduced due to the crest width, because kinetic energy can be dissipated on the crest and water on the crest can flow back towards the seaside. In coastal towns built on dune belts often a wide-crested coastal dike was constructed as both coastal protection and sea promenade. However, quantifying the effect of such a wide crest on wave overtopping is not straightforward because no empirical overtopping formulas are given in literature for this kind of configuration. Therefore physical scale model research was carried out. Also a simplified theoretical model concept was used based on an energy balance formulation of a single overtopping wave. Combining the scale model measurements with the theoretical model, a semi-empirical formula was developed and calibrated.

scholarly journals Multiphasic Study of Fluid-Dynamics and the Thermal Behavior of a Steel Ladle during Bottom Gas Injection Using the Eulerian Model

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1082
Author(s):  
Antonio Urióstegui-Hernández ◽  
Pedro Garnica-González ◽  
José Ángel Ramos-Banderas ◽  
Constantin Alberto Hernández-Bocanegra ◽  
Gildardo Solorio-Díaz
Keyword(s):  
Heat Exchange ◽  
Thermal Behavior ◽  
Gas Flow ◽  
Fluid Dynamic ◽  
Steel Slag ◽  
Scale Model ◽  
Discrete Ordinates ◽  
Transfer Model ◽  
Steel Ladle ◽  
Physical Scale

In this work, the fluid dynamic and thermal behavior of steel was analyzed during argon gas stirring in a 140-t refining ladle. The Eulerian multiphase mathematical model was used in conjunction with the discrete ordinates (DO) thermal radiation model in a steel-slag-argon system. The model was validated by particle image velocimetry (PIV) and the analysis of the opening of the oil layer in a physical scale model. The effect of Al2O3 and Mg-C as a refractory in the walls was studied, and the Ranz-Marshall and Tomiyama models were compared to determine the heat exchange coefficient. The results indicated that there were no significant differences between these heat exchange models; likewise, the radiation heat transfer model adequately simulated the thermal behavior according to plant measurements, finding a thermal homogenization time of the steel of 2.5 min for a gas flow of 0.45 Nm3·min−1. Finally, both types of refractory kept the temperature of the steel within the ranges recommended in the plant; however, the use of Al2O3 had better heat retention, which would favor refining operations.

scholarly journals Roughness Lengths for Momentum and Heat Derived from Outdoor Urban Scale Models

2007 ◽  
Vol 46 (7) ◽  
pp. 1067-1079 ◽  
Author(s):  
M. Kanda ◽  
M. Kanega ◽  
T. Kawai ◽  
R. Moriwaki ◽  
H. Sugawara
Keyword(s):  
Wind Direction ◽  
Roughness Length ◽  
Scale Dependence ◽  
Scale Model ◽  
Small Scale ◽  
Physical Scale ◽  
Scale Models ◽  
Roughness Lengths ◽  
Urban Sites ◽  
Obstacle Height

Abstract Urban climate experimental results from the Comprehensive Outdoor Scale Model (COSMO) were used to estimate roughness lengths for momentum and heat. Two different physical scale models were used to investigate the scale dependence of the roughness lengths; the large scale model included an aligned array of 1.5-m concrete cubes, and the small scale model had a geometrically similar array of 0.15-m concrete cubes. Only turbulent data from the unstable boundary layers were considered. The roughness length for momentum relative to the obstacle height was dependent on wind direction, but the scale dependence was not evident. Estimated values agreed well with a conventional morphometric relationship. The logarithm of the roughness length for heat relative to the obstacle height depended on the scale but was insensitive to wind direction. COSMO data were used successfully to regress a theoretical relationship between κB−1, the logarithmic ratio of roughness length for momentum to heat, and Re*, the roughness Reynolds number. Values of κB−1 associated with Re* for three different urban sites from previous field experiments were intercompared. A surprising finding was that, even though surface geometry differed from site to site, the regressed function agreed with data from the three urban sites as well as with the COSMO data. Field data showed that κB−1 values decreased as the areal fraction of vegetation increased. The observed dependency of the bulk transfer coefficient on atmospheric stability in the COSMO data could be reproduced using the regressed function of Re* and κB−1, together with a Monin–Obukhov similarity framework.

AN EXPERIMENTAL STUDY ON THE RELATIVE MOTIONS BETWEEN A FLOATING HARBOUR TRANSHIPPER AND A FEEDER VESSEL IN REGULAR WAVES

2021 ◽  
Vol 154 (A2) ◽  
Author(s):  
G J Macfarlane ◽  
T Lilienthal ◽  
R J Ballantyne ◽  
S Ballantyne
Keyword(s):  
Open Water ◽  
Scale Model ◽  
Regular Waves ◽  
Inclement Weather ◽  
Port Operations ◽  
Physical Scale ◽  
Feeder Vessel ◽  
Primary Advantage ◽  
Exposed Location ◽  
Relative Motions

The Floating Harbour Transhipper (FHT) is a pioneering logistics solution that was designed to meet the growing demands for coastal transhipment in the mining sector as well as commercial port operations. The primary advantage of the FHT system is that it can reduce transhipment delays caused by inclement weather, by reducing relative motions between the FHT and feeder vessel. The feeder is sheltered when inside the FHT well dock when compared to the more exposed location when a feeder is in a traditional side-by-side mooring arrangement. This paper discusses previously published studies into the relative motions of vessels engaged in side-by-side mooring arrangements and also presents details and results from a series of physical scale model experiments. In these experiments, both side-by-side and aft well dock mooring arrangements are investigated. The results provide strong evidence that the FHT well dock concept can significantly reduce the heave, pitch and roll motions of feeder vessels when transhipping in open seas – this being the cornerstone of any successful open water transhipment operation.

Experimental Investigation of Hydraulic-Pneumatic Regenerative Braking System

2015 ◽  
Author(s):  
A. G. Agwu Nnanna ◽  
Erik Rolfs ◽  
James Taylor ◽  
Karla Ariadny Freitas Ferreira
Keyword(s):  
Experimental Investigation ◽  
Kinetic Energy ◽  
Power Output ◽  
Energy Recovery ◽  
Scale Model ◽  
Regenerative Braking ◽  
Gear Pump ◽  
Braking System ◽  
Light Duty ◽  
Overall Efficiency

Design and development of energy efficient vehicles is of paramount importance to the automobile industry. Energy efficiency can be enhanced through recovery of the kinetic energy lost in the form of waste heat during braking. The kinetic energy could be converted into a reusable energy source and aid in acceleration, hence the braking system would contribute to improving the overall efficiency of a vehicle. Hydraulic-Pneumatic Regenerative Braking (HPRB) systems are a hybrid drive system that works in tandem with a vehicle’s engine and drivetrain to improve efficiency and fuel-economy. A HPRB system functions by recovering the energy typically lost to heat during vehicle braking, and storing this energy as a reusable source that can propel a vehicle from a stop. The major advantages of a HPRB system are that a vehicle would not require its engine to run during braking to stop, nor would the engine be required to accelerate the vehicle initially from a stop. The benefit realized by this system is an increase in fuel-efficiency, reduced vehicle emissions, and overall financial savings. An HPRB system aids in slowing a vehicle by creating a drag on the driveline as it recovers and stores energy during braking. Therefore, HPRB system operation reduces wear by minimizing the amount of work performed by the brake pads and rotors. An experimental investigation of Hydraulic-Pneumatic Regenerative Braking (HPRB) system was conducted to measure the system’s overall efficiency and available power output. The HPRB in this study is a 1/10th lab-scale model of a light-duty four wheel vehicle. The design/size was based on a 3500 lbs light-duty four wheel vehicle with an estimated passenger weight of 500 lbs. It was assumed that the vehicle can accelerate from 0–15 mph in 2 seconds. The aim of this work is to examine the effect of heat losses due to irreversibility on energy recovery. The experimental facility consisted of a hydraulic pump, two hydraulic-pneumatic accumulators, solenoid and relief valves, and data acquisition system. The HPRB system did not include any driveline components necessary to attach this system onto a vehicle’s chassis rather an electric motor was used to drive the pump and simulate the power input to the system from a spinning drive shaft. Pressure transducers, Hall effects sensor, and thermocouples were installed at suction and discharge sections of the hydraulic and pneumatic components to measure hydrodynamic and thermos-physical properties. The measured data were used to determine the system’s energy recovery and power delivery efficiency. Results showed that the HPRB system is capable of recovering 47% of the energy input to the system during charging, and 64% efficient in power output during discharging with an input and output of 0.33 and 0.21 horsepower respectively. Inefficiencies during operation were attributed to heat generation from the gear pump but especially due to the piston accumulator, where heat loss attributed to a 12% reduction in energy potential alone.

scholarly journals THE USE OF ARRAY PROCESSORS FOR NUMERICAL MODELLING OF TIDAL ESTUARY DYNAMICS

1980 ◽  
Vol 1 (17) ◽  
pp. 142
Author(s):  
D. Prandle ◽  
E.R. Funke ◽  
N.L. Crookshank ◽  
R. Renner
Keyword(s):  
Numerical Model ◽  
Numerical Modelling ◽  
Hybrid Model ◽  
Numerical Models ◽  
Computer Time ◽  
Scale Model ◽  
Hybrid Modelling ◽  
Tidal Propagation ◽  
Physical Scale ◽  
Array Processors

The use of array processors for the numerical modelling of estuarine systems is discussed here in the context of "hybrid modelling", however, it is shown that array processors may be used to advantage in independent numerical simulations. Hybrid modelling of tidal estuaries was first introduced by fiolz (1977) and later by Funke and Crookshank (1978). In a hybrid model, tidal propagation in an estuary is simulated by dynamically linking an hydraulic (or physical) scale model of part of the estuary to a numerical model of the remaining part in a manner such that a free interchange of flow occurs at the interface(s). Typically, the elevation of the water surface at the boundary of the scale model is measured and transmitted to the numerical model. In return, the flow computed at the boundary of the numerical model is fed directly into the scale model. This approach enables the extent of the scale model to be limited to the area of immediate interest (or to that area where flow conditions are such that they can be most accurately simulated by a scale model). In addition, since the region simulated by the numerical model can be extended almost indefinitely, the problems of spurious reflections from downstream boundaries can be eliminated. In normal use, numerical models are evaluated on the basis of computing requirements, cost and accuracy. The computer time required to simulate one tide cycle is, in itself, seldom of interest except in so far as it affects the above criteria. However in hybrid modelling this parameter is often paramount since concurrent operation of the numerical and scale models requires that the former must keep pace with the latter. The earlier hybrid model of the St. Lawrence (Funke and Crookshank, 1978) involved a one-dimensional numerical model of the upstream regions of the river. However, future applications are likely to involve extensive two-dimensional numerical simulation.

Advancing the simulation of mesoscale eddies: Backscatter schemes in eddy-permitting ocean simulations

2021 ◽  
Author(s):  
Stephan Juricke ◽  
Sergey Danilov ◽  
Marcel Oliver ◽  
Nikolay Koldunov ◽  
Dmitry Sidorenko ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Large Scale ◽  
Mesoscale Eddy ◽  
Ocean Model ◽  
Mean Flow ◽  
Ocean Coupling ◽  
Climate Simulations ◽  
Flow Interactions ◽  
To Come ◽  
Eddy Dynamics

<p>Capturing mesoscale eddy dynamics is crucial for accurate simulations of the large-scale ocean currents as well as oceanic and climate variability. Eddy-mean flow interactions affect the position, strength and variations of mean currents and eddies are important drivers of oceanic heat transport and atmosphere-ocean-coupling. However, simulations at eddy-permitting resolutions are substantially underestimating eddy variability and eddy kinetic energy many times over. Such eddy-permitting simulations will be in use for years to come, both in coupled and uncoupled climate simulations. We present a set of kinetic energy backscatter schemes with different complexity as alternative momentum closures that can alleviate some eddy related biases such as biases in the mean currents, in sea surface height variability and in temperature and salinity. The complexity of the schemes reflects in their computational costs, the related simulation improvements and their adaptability to different resolutions. However, all schemes outperform classical viscous closures and are computationally less expensive than a related necessary resolution increase to achieve similar results. While the backscatter schemes are implemented in the ocean model FESOM2, the concepts can be adjusted to any ocean model including NEMO.</p>

scholarly journals Modeling Storm Surge Attenuation by an Integrated Nature-Based and Engineered Flood Defense System in the Scheldt Estuary (Belgium)

2020 ◽  
Vol 8 (1) ◽  
pp. 27
Author(s):  
Sven Smolders ◽  
Maria João Teles ◽  
Agnès Leroy ◽  
Tatiana Maximova ◽  
Patrick Meire ◽  
...  
Keyword(s):  
Storm Surge ◽  
Flood Control ◽  
Storm Surges ◽  
Scheldt Estuary ◽  
Scale Model ◽  
Defense System ◽  
Height Reduction ◽  
Flood Defense ◽  
Physical Scale ◽  
Surge Height

There is increasing interest in the use of nature-based approaches for mitigation of storm surges along coasts, deltas, and estuaries. However, very few studies have quantified the effectiveness of storm surge height reduction by a real-existing, estuarine-scale, nature-based, and engineered flood defense system, under specific storm surge conditions. Here, we present data and modelling results from a specific storm surge in the Scheldt estuary (Belgium), where a hybrid flood defense system is implemented, consisting of flood control areas, of which some are restored into tidal marsh ecosystems, by use of culvert constructions that allow daily reduced tidal in- and outflow. We present a hindcast simulation of the storm surge of 6 December 2013, using a TELEMAC-3D model of the Scheldt estuary, and model scenarios showing that the hybrid flood defense system resulted in a storm surge height reduction of up to half a meter in the estuary. An important aspect of the work was the implementation of model formulations for calculating flow through culverts of restored marshes. The latter was validated comparing simulated and measured discharges through a physical scale model of a culvert, and through a real-scale culvert of an existing restored marsh during the storm surge.

Multi Vessel Interaction in Shallow Water

2009 ◽  
Author(s):  
Hans Fabricius Hansen ◽  
Stefan Carstensen ◽  
Erik Damgaard Christensen ◽  
Jens Kirkegaard
Keyword(s):  
Shallow Water ◽  
Wave Model ◽  
Irregular Waves ◽  
Numerical Code ◽  
Scale Model ◽  
Hydrodynamic Characteristics ◽  
Mooring Line ◽  
Industry Standard ◽  
Physical Scale ◽  
The Time Domain

A numerical package for simulating vessel motions in the time domain, WAMSIM, is extended to handle multiple moving bodies interconnected through a nonlinear mooring system. WAMSIM relies on the industry standard program WAMIT to calculate the hydrodynamic characteristics and interaction of multiple bodies in the frequency domain. The numerical code is used to simulate the motions and mooring line and fender forces of two LNG tankers moored side-by-side in shallow water. One of the gas tankers is moored to the sea floor through a turret with chain catenaries. Realistic short-crested irregular waves obtained from a Boussinesq wave model are used to force the model. Motion spectra of the simulated motions are compared to measured motions from physical scale model tests. The model shows good agreement with measured motions and mooring line forces.

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