Detection of In-site and Cause Analysis of Splitting Cracks of Vertical Wall for Large-scale three-direction Pre-stressed Aqueduct

AbstractWhen the classical Rayleigh–Bénard (RB) system is rotated about its vertical axis roughly three regimes can be identified. In regime I (weak rotation) the large-scale circulation (LSC) is the dominant feature of the flow. In regime II (moderate rotation) the LSC is replaced by vertically aligned vortices. Regime III (strong rotation) is characterized by suppression of the vertical velocity fluctuations. Using results from experiments and direct numerical simulations of RB convection for a cell with a diameter-to-height aspect ratio equal to one at $\mathit{Ra}\ensuremath{\sim} 1{0}^{8} \text{{\ndash}} 1{0}^{9} $ ($\mathit{Pr}= 4\text{{\ndash}} 6$) and $0\lesssim 1/ \mathit{Ro}\lesssim 25$ we identified the characteristics of the azimuthal temperature profiles at the sidewall in the different regimes. In regime I the azimuthal wall temperature profile shows a cosine shape and a vertical temperature gradient due to plumes that travel with the LSC close to the sidewall. In regimes II and III this cosine profile disappears, but the vertical wall temperature gradient is still observed. It turns out that the vertical wall temperature gradient in regimes II and III has a different origin than that observed in regime I. It is caused by boundary layer dynamics characteristic for rotating flows, which drives a secondary flow that transports hot fluid up the sidewall in the lower part of the container and cold fluid downwards along the sidewall in the top part.

Download Full-text

Large Scale Experimental Wave Impact on Walls in the Québec Coastal Physics Laboratory

Volume 7: Ocean Engineering ◽

10.1115/omae2015-42335 ◽

2015 ◽

Author(s):

Jannette B. Frandsen ◽

Francis Bérubé

Keyword(s):

Large Scale ◽

Peak Pressure ◽

Vertical Wall ◽

Test Series ◽

Vertical Force ◽

Wave Impact ◽

Physics Laboratory ◽

Air Pocket ◽

Jet Velocity ◽

Plunging Breaker

The present tests are conducted in the new Québec Coastal Physics Laboratory, Canada. The flume has a depth and a width of 5 m and is 120 m long. This paper presents large scale experiments of water wave impact on a vertical wall following wave runup on a mixed sand-gravel-cobble beach. This present study is concerned with advancing knowledge on rapidly varying pressure magnitude and distributions on different types of sea/river/harbor walls. Protection against extreme events and subsequent coastal erosion is a key theme of application. Herein is presented preliminary test series which has focus on forces on vertical walls. Specifically, 27 pressure sensors are mounted on the vertical wall with a total test area of 1.2 m wide and 2.4 m high and is a stiffened aluminum plate. The outer regions of the wall are made of steel to span the entire width of the tank. The wall is designed to behave as a rigid plate. The geometric model to full scale is about 1:4. The incoming waves evolve on a flat bed to climb the final 25 m on a beach with slope with constant slope of 1:10. A small regular wave train forms the basis for investigations of force patterns on the wall. Herein, our preliminary findings reported are based on selected 6 test series (18 impacts out of 150 impacts). In general, wall pressures greater than 1 MPa and 10 m run-up are easily developed even with moderate amplitude waves at the inlet. We will discuss some details of the underlying mechanism of various types of breaking and impact on the wall. The peak pressure identified on the wall with the mixed gravel beach surface was 1.23 million N/m2 occurring in 0.2 milli seconds. It was cuased by a plunging breaker with a relatively large air pocket (∼0.11 m2). It was further identified that the maximum pressure on the wall does not necessarily give the maximum jet velocity (equivalent to vertical force considered in design of on parapets). They are independent quantities in these very random rapid processes. The maximum jet velocity was in the order of 35 m/s but could higher on a different beach surface. Further, it was found that the maximum waves are not necessarily the most critical ones as the waves break and therefore dissipates its energy before reaching the wall. A plunging breaker with a relatively large airpocket with a crest tip located at the top part of the wall resulted in max. peak wall pressure. One impact case caused a near simultaneous double peak pressure generated by a plunging breaker with two relatively small airpockets (0.003 m2 and 0.01 m2). This was the impact case responsible for the max. vertical jet velocity. We further found that the max. peak water pressure of the plunging breakers had a similar order of magnitude as the max. pressure within an air pocket.

Download Full-text

Conditions for extreme wave runup on a vertical barrier by nonlinear dispersion

Journal of Fluid Mechanics ◽

10.1017/jfm.2014.217 ◽

2014 ◽

Vol 748 ◽

pp. 768-788 ◽

Cited By ~ 24

Author(s):

Claudio Viotti ◽

Francesco Carbone ◽

Frédéric Dias

Keyword(s):

Large Scale ◽

Vertical Wall ◽

Propagation Path ◽

Physical Parameters ◽

Propagation Time ◽

Mathematical Framework ◽

Wave Runup ◽

Fully Nonlinear ◽

Strongly Nonlinear ◽

Nonlinear Modulation

AbstractThe runup of long strongly nonlinear waves impinging on a vertical wall can exceed six times the far-field amplitude of the incoming waves. This outcome stems from a precursory evolution process in which the wave height undergoes strong amplification due to the combined action of nonlinear steepening and dispersion, resulting in the formation of nonlinearly dispersive wave trains, i.e. undular bores. This part of the problem is first analysed separately, with emphasis on the wave amplitude growth rate during the development of undular bores within an evolving large-scale background. The growth of the largest wave in the group is seen to reflect the asymptotic time scaling provided by nonlinear modulation theory rather closely, even in the case of fully nonlinear evolution and moderately slow modulations. In order to address the effect of such a dynamics on the subsequent wall runup, numerical simulations of evolving long-wave groups are then carried out in a computational wave tank delimited by vertical walls. Conditions for optimal runup efficiency are sought with respect to the main physical parameters characterizing the incident waves, namely the wavelength, the length of the propagation path and the initial amplitude. Extreme runup is found to be strongly correlated to the ratio between the available propagation time and the shallow-water nonlinear time scale. The problem is studied in the twofold mathematical framework of the fully nonlinear free-surface Euler equations and the strongly nonlinear Serre–Green–Naghdi model. The performance of the reduced model in providing accurate long-time predictions can therefore be assessed.

Download Full-text

LOADING OF VERTICAL WALLS BY OVERTOPPING BORES USING PRESSURE AND FORCE SENSORS - A LARGE SCALE MODEL STUDY

Coastal Engineering Proceedings ◽

10.9753/icce.v33.currents.44 ◽

2012 ◽

Vol 1 (33) ◽

pp. 44 ◽

Cited By ~ 2

Author(s):

Karunya Ramachandran ◽

Rebeca Roldan Genzalez ◽

Hocine Oumeraci ◽

Stefan Schimmels ◽

Matthias Kudella ◽

...

Keyword(s):

Large Scale ◽

Vertical Wall ◽

Pressure Sensors ◽

Scale Model ◽

Force Sensors ◽

Research Project ◽

Joint Research ◽

Large Wave ◽

Wave Flume ◽

Joint Research Project

This study is based on the data obtained from tests carried out in the Large Wave Flume (Grosser Wellenkanal (GWK)) in Hannover in the frame of a joint research project of Ghent University (Belgium) and Forschungszentrum Küste (FZK, Germany). The goal of the research project is to determine the wave induced loads on vertical storm walls located at the end of overtopped dike, which are designed to protect coastal cities from overtopping and floods. The loads resulting from waves overtopping the dike and impacting the vertical wall as a bore are measured by means of both force and pressure sensors. This paper describes the results of pressure and force records at the vertical wall, including a comparative analysis of the overall forces obtained by pressure integration and force sensors for two different wall setups: Fully blocked wall and partially blocked wall.

Download Full-text

Towards a Timely Root Cause Analysis for Complex Situations in Large Scale Telecommunications Networks

Procedia Computer Science ◽

10.1016/j.procs.2015.08.115 ◽

2015 ◽

Vol 60 ◽

pp. 160-169 ◽

Cited By ~ 2

Author(s):

Marc Schaaf ◽

Gwendolin Wilke ◽

Topi Mikkola ◽

Erik Bunn ◽

Ilkka Hela ◽

...

Keyword(s):

Large Scale ◽

Root Cause Analysis ◽

Telecommunications Networks ◽

Cause Analysis ◽

Root Cause

Download Full-text

Coherent Structures in Shallow Water Jets

Journal of Fluids Engineering ◽

10.1115/1.4003194 ◽

2011 ◽

Vol 133 (1) ◽

Cited By ~ 11

Author(s):

A.-M. Shinneeb ◽

J. D. Bugg ◽

R. Balachandar

Keyword(s):

Coherent Structures ◽

Horizontal Plane ◽

Large Scale ◽

Solid Wall ◽

Vertical Wall ◽

Vertical Plane ◽

Vertical Direction ◽

Particle Image Velocimetry System ◽

Identification Algorithm ◽

Vortical Structures

This paper reports an experimental investigation of a round jet discharging horizontally from a vertical wall into an isothermal body of water confined in the vertical direction by a flat wall on the bottom and a free surface on top. Specifically, this paper focuses on the effects of vertical confinement on the characteristics of large vortical structures. The jet exit velocity was 2.5 m/s, and the exit Reynolds number was 22,500. Experiments were performed at water layer depths corresponding to 15, 10, and 5 times the jet exit diameter (9 mm). The large-scale structures were exposed by performing a proper orthogonal decomposition (POD) analysis of the velocity field obtained using a particle image velocimetry system. Measurements were made on vertical and horizontal planes—both containing the axis of the jet. All fields-of-view were positioned at an axial location in the range 10<x/D<80. The number of modes used for the POD reconstruction of the velocity fields was selected to recover ∼40% of the turbulent kinetic energy. A vortex identification algorithm was then employed to quantify the size, circulation, and direction of rotation of the exposed vortices. A statistical analysis of the distribution of number, size, and strength of the identified vortices was carried out to explore the characteristics of the coherent structures. The results clearly reveal the existence of numerous vortical structures of both rotational senses in the jet flow, and their number generally decreases in the axial direction while their size increases. The size of vortices identified in the vertical plane is restricted by the water depth, while they are allowed to increase in size in the horizontal plane. Moreover, the results show a significant decrease in the number of small vortices for the shallowest case in the horizontal plane, with a corresponding increase in the number of large vortices and a significant increase in their size. This behavior was accompanied with an increase in the vortex circulation in the horizontal plane and a reduction in the circulation in the vertical plane. This is indicative of the dominance of the pairing process due to shallowness. Moreover, the balance between the positive and negative vortices in the vertical plane changed because of the formation of negative (clockwise) vortices near the solid wall at downstream locations.

Download Full-text

MBO of Chinese State-Owned SMEs: Fate and the Way Out

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.268-270.737 ◽

2011 ◽

Vol 268-270 ◽

pp. 737-741

Author(s):

Pin Xie

Keyword(s):

Information Disclosure ◽

Large Scale ◽

The State ◽

Cause Analysis ◽

Management Level ◽

Law System ◽

Financing Channels ◽

Inadequate Information ◽

The Status ◽

Countermeasures And Suggestions

While approval for MBO of large-scale enterprises has been suspended, MBO of the state-owned SMEs has set off a new round of MBO wave. Chinese primary state-owned and collective SMEs unify management rights and ownership through the implementation of MBO, with property rights being clear to the natural person of the management level and the reform being of certain spontaneity. However, the state-owned SMEs have such widespread problems as unperfected law system, narrow financing channels and inadequate information disclosure in the process of implementation. Based on the status, problems and cause analysis of implementation of MBO in Chines state-owned SMEs at this stage and aiming at the law, financing, pricing, information disclosure and other issues within, this paper puts forward countermeasures and suggestions related to further improving MBO of Chinese SMEs.

Download Full-text

Mixture Fraction Statistics of Plane Self-Preserving Buoyant Turbulent Adiabatic Wall Plumes

Journal of Heat Transfer ◽

10.1115/1.2826073 ◽

1999 ◽

Vol 121 (4) ◽

pp. 837-843 ◽

Cited By ~ 11

Author(s):

R. Sangras ◽

Z. Dai ◽

G. M. Faeth

Keyword(s):

Large Scale ◽

Mixture Fraction ◽

Vertical Wall ◽

Power Spectra ◽

Probability Density Functions ◽

Density Functions ◽

Adiabatic Wall ◽

Integral Scales ◽

Smooth Plane ◽

Motion Measurements

Measurements of the mixture fraction properties of plane buoyant turbulent adiabatic wall plumes (adiabatic wall plumes) are described, emphasizing conditions far from the source where self-preserving behavior is approximated. The experiments involved helium/air mixtures rising along a smooth, plane and vertical wall. Mean and fluctuating mixture fractions were measured using laser-induced iodine fluorescence. Self-preserving behavior was observed 92–155 source widths above the source, yielding smaller normalized plume widths and near-wall mean mixture fractions than earlier measurements. Self-preserving adiabatic wall plumes mix slower than comparable free line plumes (which have 58 percent larger normalized widths) because the wall prevents mixing on one side and inhibits large-scale turbulent motion. Measurements of probability density functions, temporal power spectra, and temporal integral scales of mixture fraction fluctuations are also reported.

Download Full-text

Small to large scale mixed turbulent convection: buildings application

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-10-2017-0392 ◽

2018 ◽

Vol 28 (1) ◽

pp. 188-205 ◽

Cited By ~ 6

Author(s):

Souad Morsli ◽

Mustapha Boussoufi ◽

Amina Sabeur ◽

Mohammed El Ganaoui ◽

Rachid Bennacer

Keyword(s):

Flow Structure ◽

Large Scale ◽

Natural Ventilation ◽

Vertical Wall ◽

Cold Temperature ◽

Temperate Climate ◽

3D Flow ◽

Content Type ◽

Hot Temperature ◽

The One

Purpose The use of natural ventilation by large openings to maintain thermal comfort conditions in the premises is a concept that is perfectly integrated into the traditional architecture of countries in the Mediterranean region or in tropical climates. In a temperate climate where the architecture is not usually designed to respond to the use of natural ventilation is seasonal and is done at the initiative of the occupants by making changes in the design of their doors. The European interest in natural ventilation, as a passive building air-conditioning technology, is increasing and has been the subject of a research program commissioned by the European Community. In this work, the authors consider a part of a housing compound as a refreshing floor. This floor is maintained at a constant cold temperature, the one vertical wall at hot temperature and other surfaces are adiabatic. Various scenarios are considered for this work. Mixed convection for different boundary conditions and different configurations is carried out. In addition, an airflow is injected through a window and extracted on the opposite window. Classical conclusion and transitional value on Richardson number have been completed by the new thermal configuration with nonsymmetric thermal conditions. The complex 3D flow structure is more obvious when one of the two flows (ventilation or natural convection) dominates. However, the induced heat transfer is less sensitive to the added ventilation. In this study, the authors consider a part of a housing compound as a refreshing floor. This floor is maintained at a constant cold temperature, the one vertical wall at hot temperature and other surfaces are adiabatic. Design/methodology/approach This is a qualitative preliminary study of a 2D–3D flow. The authors examine the competition between the natural convective flow and the added airflow on the flow structure and indoor air quality. The numerical model shows a good agreement with that obtained by researchers analytically and experimentally. To deal with turbulence, the RNG k-ε model has been adopted in this study. Findings The transfer is more sensitive between the 2D and 3D cases for the present analyzed case. Originality/value The study of ventilation efficiency has shown the competition between the big and small structures and the induced discomfort.

Download Full-text