Blockage correction for pier scour experiments

2018 ◽  
Vol 45 (5) ◽  
pp. 413-417 ◽  
Author(s):  
Priscilla Williams ◽  
Tirupati Bolisetti ◽  
Ram Balachandar
Keyword(s):  
Prediction Method ◽  
Flow Conditions ◽  
Mean Flow ◽  
Equilibrium Conditions ◽  
Pier Scour ◽  
Separation Velocity ◽  
Channel Blockage ◽  
Flow Intensity ◽  
Bridge Pier Scour

Commonly used bridge pier scour prediction equations have often employed the quantities of relative coarseness, flow shallowness, and flow intensity to yield a design value for maximum relative scour depth at equilibrium conditions. Predictive methods based on these quantities tend to over-predict scour. Moreover, these equations tend to yield different scour estimates for the same flow conditions. The equations, mostly derived from laboratory estimates of scour, have not considered the influence of the flume sidewall proximity. New experiments are conducted to specifically identify the role of channel blockage on scour. Evaluation of results indicates that the influence of blockage ratio on scour can be described using the value of mean flow velocity along the separating streamline and the ratio of the separation velocity to the critical velocity in the form of new parameter kc. A new scour prediction method is developed and presented.

Dimensional analysis of bridge pier scour and the role of flow intensity

2006 ◽  
Author(s):  
M Ortega-S√°nchez ◽  
G L√≥pez ◽  
L Teixeira ◽  
E Fernandez ◽  
G Simarro
Keyword(s):  
Dimensional Analysis ◽  
Bridge Pier ◽  
Pier Scour ◽  
Flow Intensity ◽  
Bridge Pier Scour

scholarly journals A Linearized Euler Analysis of Unsteady Transonic Flows in Turbomachinery

1993 ◽  
Author(s):  
Kenneth C. Hall ◽  
William S. Clark ◽  
Christopher B. Lorence
Keyword(s):  
Unsteady Flow ◽  
Three Dimensional ◽  
Computational Method ◽  
Shock Capturing ◽  
Flow Conditions ◽  
Mean Flow ◽  
Transonic Flows ◽  
Linearized Euler Equations ◽  
Volume Equations

A computational method for efficiently predicting unsteady transonic flows in two- and three-dimensional cascades is presented. The unsteady flow is modelled using a linearized Euler analysis whereby the unsteady flow field is decomposed into a nonlinear mean flow plus a linear harmonically varying unsteady flow. The equations that govern the perturbation flow, the linearized Euler equations, are linear variable coefficient equations. For transonic flows containing shocks, shock capturing is used to model the shock impulse (the unsteady load due to the harmonic motion of the shock). A conservative Lax-Wendroff scheme is used to obtain a set of linearized finite volume equations that describe the harmonic small disturbance behavior of the flow. Conditions under which such a discretization will correctly predict the shock impulse are investigated. Computational results are presented that demonstrate the accuracy and efficiency of the present method as well as the essential role of unsteady shock impulse loads on the flutter stability of fans.

scholarly journals Bridge pier scour under pressure flow conditions

2019 ◽  
Vol 35 (7) ◽  
pp. 844-854 ◽  
Author(s):  
Iacopo Carnacina ◽  
Stefano Pagliara ◽  
Nicoletta Leonardi
Keyword(s):  
Bridge Pier ◽  
Flow Conditions ◽  
Pier Scour ◽  
Pressure Flow ◽  
Bridge Pier Scour

scholarly journals Sensitivity analysis of bridge pier scour depth predictive formulae

2013 ◽  
Vol 15 (3) ◽  
pp. 939-951 ◽  
Author(s):  
Roberto Gaudio ◽  
Ali Tafarojnoruz ◽  
Samuele De Bartolo
Keyword(s):  
Sensitivity Analysis ◽  
Scour Depth ◽  
Relative Importance ◽  
Pier Scour ◽  
Sediment Size ◽  
Causative Factors ◽  
Flow Intensity ◽  
Influencing Parameters ◽  
Input Variables ◽  
Bridge Pier Scour

Sensitivity analysis is an approach to recognising the behaviour of models and relative importance of causative factors. In this paper, behaviours of six pier scour depth empirical formulae are evaluated on the basis of an analytical method. The sensitivity of predicted scour depth is analysed with respect to the following independent parameters: approach flow depth, riverbed slope and median sediment size. Also their combined influence is studied examining the relative importance of each parameter with respect to the total variation of the maximum scour depth. Results show that: (1) sensitivity significantly depends on flow intensity for most of the selected formulae, whereas for the others it is a constant value or depends on other influencing parameters; (2) different formulae demonstrate various level of sensitivity to the input variables, so that, for a certain error in the input variables, the error in the results may vary consistently; (3) some formulae are very sensitive to the input parameters under some conditions, hence an error in an input variable may be amplified in the output results; and (4) most of the formulae are more sensitive to the variations of the influencing parameters in clear-water than in live-bed conditions.

Bridge pier scour mitigation under steady and unsteady flow conditions

2012 ◽  
Vol 60 (4) ◽  
pp. 1076-1097 ◽  
Author(s):  
Ali Tafarojnoruz ◽  
Roberto Gaudio ◽  
Francesco Calomino
Keyword(s):  
Unsteady Flow ◽  
Bridge Pier ◽  
Flow Conditions ◽  
Pier Scour ◽  
Bridge Pier Scour

scholarly journals A Linearized Euler Analysis of Unsteady Transonic Flows in Turbomachinery

1994 ◽  
Vol 116 (3) ◽  
pp. 477-488 ◽  
Author(s):  
K. C. Hall ◽  
W. S. Clark ◽  
C. B. Lorence
Keyword(s):  
Unsteady Flow ◽  
Three Dimensional ◽  
Computational Method ◽  
Shock Capturing ◽  
Flow Conditions ◽  
Mean Flow ◽  
Transonic Flows ◽  
Linearized Euler Equations ◽  
Volume Equations

A computational method for efficiently predicting unsteady transonic flows in two-and three-dimensional cascades is presented. The unsteady flow is modeled using a linearized Euler analysis whereby the unsteady flow field is decomposed into a nonlinear mean flow plus a linear harmonically varying unsteady flow. The equations that govern the perturbation flow, the linearized Euler equations, are linear variable coefficient equations. For transonic flows containing shocks, shock capturing is used to model the shock impulse (the unsteady load due to the harmonic motion of the shock). A conservative Lax–Wendroff scheme is used to obtain a set of linearized finite volume equations that describe the harmonic small disturbance behavior of the flow. Conditions under which such a discretization will correctly predict the shock impulse are investigated. Computational results are presented that demonstrate the accuracy and efficiency of the present method as well as the essential role of unsteady shock impulse loads on the flutter stability of fans.

Platelet and Shear Rate Promote Tumor Cell Adhesion to Human Endothelial Extracellular Matrix - Absence of a Role for Platelet Cyclooxygenase

1989 ◽  
Vol 61 (03) ◽  
pp. 485-489 ◽  
Author(s):  
Eva Bastida ◽  
Lourdes Almirall ◽  
Antonio Ordinas
Keyword(s):  
Cell Adhesion ◽  
Shear Rate ◽  
Tumor Cell ◽  
Umbilical Vein ◽  
Blood Platelets ◽  
Flow Conditions ◽  
Tumor Cell Adhesion ◽  
Rate Dependent ◽  
Static Conditions

SummaryBlood platelets are thought to be involved in certain aspects of malignant dissemination. To study the role of platelets in tumor cell adherence to vascular endothelium we performed studies under static and flow conditions, measuring tumor cell adhesion in the absence or presence of platelets. We used highly metastatic human adenocarcinoma cells of the lung, cultured human umbilical vein endothelial cells (ECs) and extracellular matrices (ECM) prepared from confluent EC monolayers. Our results indicated that under static conditions platelets do not significantly increase tumor cell adhesion to either intact ECs or to exposed ECM. Conversely, the studies performed under flow conditions using the flat chamber perfusion system indicated that the presence of 2 × 105 pl/μl in the perfusate significantly increased the number of tumor cells adhered to ECM, and that this effect was shear rate dependent. The maximal values of tumor cell adhesion were obtained, in presence of platelets, at a shear rate of 1,300 sec-1. Furthermore, our results with ASA-treated platelets suggest that the role of platelets in enhancing tumor cell adhesion to ECM is independent of the activation of the platelet cyclooxygenase pathway.

BRIDGE PIER SCOUR: A REVIEW OF PROCESSES, MEASUREMENTS AND ESTIMATES

2012 ◽  
Vol 11 (5) ◽  
pp. 975-989 ◽  
Author(s):  
Luigia Brandimarte ◽  
Paolo Paron ◽  
Giuliano Di Baldassarre
Keyword(s):  
Bridge Pier ◽  
Pier Scour ◽  
Bridge Pier Scour

scholarly journals Forensic Investigation of Four Monitored Green Infrastructure Inlets

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1787
Author(s):  
Leena J. Shevade ◽  
Franco A. Montalto
Keyword(s):  
Measurement Uncertainty ◽  
Green Infrastructure ◽  
Stormwater Management ◽  
Catchment Area ◽  
Low Flow ◽  
Inflow Rate ◽  
Forensic Investigation ◽  
Flow Conditions ◽  
The Mean

Green infrastructure (GI) is viewed as a sustainable approach to stormwater management that is being rapidly implemented, outpacing the ability of researchers to compare the effectiveness of alternate design configurations. This paper investigated inflow data collected at four GI inlets. The performance of these four GI inlets, all of which were engineered with the same inlet lengths and shapes, was evaluated through field monitoring. A forensic interpretation of the observed inlet performance was conducted using conclusions regarding the role of inlet clogging and inflow rate as described in the previously published work. The mean inlet efficiency (meanPE), which represents the percentage of tributary area runoff that enters the inlet was 65% for the Nashville inlet, while at Happyland the NW inlet averaged 30%, the SW inlet 25%, and the SE inlet 10%, considering all recorded events during the monitoring periods. The analysis suggests that inlet clogging was the main reason for lower inlet efficiency at the SW and NW inlets, while for the SE inlet, performance was compromised by a reverse cross slope of the street. Spatial variability of rainfall, measurement uncertainty, uncertain tributary catchment area, and inlet depression characteristics are also correlated with inlet PE. The research suggests that placement of monitoring sensors should consider low flow conditions and a strategy to measure them. Additional research on the role of various maintenance protocols in inlet hydraulics is recommended.

scholarly journals Quantifying the Effects of Wave—Current Interactions on Tidal Energy Resource at Sites in the English Channel Using Coupled Numerical Simulations

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3625
Author(s):  
Jon Hardwick ◽  
Ed B. L. Mackay ◽  
Ian G. C. Ashton ◽  
Helen C. M. Smith ◽  
Philipp R. Thies
Keyword(s):  
Wave Model ◽  
Tidal Energy ◽  
English Channel ◽  
Flow Conditions ◽  
Mean Flow ◽  
Radiation Stress ◽  
Large Wave ◽  
Stress Gradients ◽  
The Mean ◽  
Flow Power

Numerical modeling of currents and waves is used throughout the marine energy industry for resource assessment. This study compared the output of numerical flow simulations run both as a standalone model and as a two-way coupled wave–current simulation. A regional coupled flow-wave model was established covering the English Channel using the Delft D-Flow 2D model coupled with a SWAN spectral wave model. Outputs were analyzed at three tidal energy sites: Alderney Race, Big Roussel (Guernsey), and PTEC (Isle of Wight). The difference in the power in the tidal flow between coupled and standalone model runs was strongly correlated to the relative direction of the waves and currents. The net difference between the coupled and standalone runs was less than 2.5%. However, when wave and current directions were aligned, the mean flow power was increased by up to 7%, whereas, when the directions were opposed, the mean flow power was reduced by as much as 9.6%. The D-Flow Flexible Mesh model incorporates the effects of waves into the flow calculations in three areas: Stokes drift, forcing by radiation stress gradients, and enhancement of the bed shear stress. Each of these mechanisms is discussed. Forcing from radiation stress gradients is shown to be the dominant mechanism affecting the flow conditions at the sites considered, primarily caused by dissipation of wave energy due to white-capping. Wave action is an important consideration at tidal energy sites. Although the net impact on the flow power was found to be small for the present sites, the effect is site specific and may be significant at sites with large wave exposure or strong asymmetry in the flow conditions and should thus be considered for detailed resource and engineering assessments.

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