scholarly journals CFD Simulation of Local Scouring Around Bridge Pier

2019 ◽  
Vol 9 (1) ◽  
pp. 1870-1880
Keyword(s):  
Cfd Simulation ◽  
Flow Behavior ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Local Scour ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Multiphase Model ◽  
Model Studies ◽  
Dimensional Simulation

The threat of local scour around bridge piers has been in research for many years. According to the various studies, local scour around the bridge pier is the prime cause for most of the bridge failures. The main objective of the present study was to investigate the flow behavior and the scour phenomenon around the bridge piers of various shapes namely Circular, Elliptical, Square and Streamlined. Local scouring depends on various factors like depth of flow, upstream flow conditions, pier shape and dimensions. Here, we have taken only pier shape as the primary factor and kept other factors constant. The numerical simulations were even carried out using CFDFluent, Eulerian multiphase model, k–epsilon turbulence model, to elaborate the physics behind the scour formation. CFD simulation tool can be used for wide understanding of the flow behavior around the bridge piers even without physical model studies because it saves time and money as compared to experimental studies. Three dimensional simulation of flow behavior around four pier shapes indicates that the streamlined pier is the most efficient pier to use as it allows the flow to pass smoothly around it creating less obstruction to the flow and hence creating less chances of local scouring near the pier toe.

Reduction of local scour around a bridge pier by using different shapes of pier slots and collars

2020 ◽  
Vol 20 (3) ◽  
pp. 1006-1015 ◽  
Author(s):  
A. Bestawy ◽  
T. Eltahawy ◽  
A. Alsaluli ◽  
A. Almaliki ◽  
M. Alqurashi
Keyword(s):  
Three Dimensional ◽  
Laser Scanner ◽  
Local Scour ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Scour Depth ◽  
Contour Maps ◽  
Reduction Methods ◽  
Analysis System ◽  
Bridge Failure

Abstract Local scour around bridge piers is one of the main causes of bridge failure all over the world. Experimental and hydraulic models were carried out to investigate two types of scour reduction methods around a single cylindrical pier, namely the pier's slots and collars. The efficiency of various types of pier slots and circular collars around the pier's base in reducing scour were studied. A new shape of a conical collar was developed by the authors and examined along with other shapes. The results revealed that collars, in general, have more influence in reducing scour depth than slots made in the front and rear of bridge piers. The sigma-slot acts better than other tested slots, with a reduction in the scour depths of 59.3% and 52.8% at the upstream and downstream of the pier, respectively. On the other hand, the conical collar appeared to be the most effective collar shape in reducing the scour around the bridge pier, with a 61.1% reduction in the scour depth downstream of the pier. A three-dimensional laser scanner was used to capture the bed topography at the end of each experiment and contour maps of the deformed bed were produced. A one-dimensional Hydrologic Engineering Center-River Analysis System model was developed with a single bridge pier to predict the scour depth around the pier in an attempt to introduce new values for the pier nose shape factor, , which describes the tested piers.

scholarly journals Investigation of Flow Behavior around Corotating Blades in a Double-Spindle Lawn Mower Deck

2005 ◽  
Vol 2005 (1) ◽  
pp. 77-89 ◽  
Author(s):  
W. Chon ◽  
R. S. Amano
Keyword(s):  
Flow Pattern ◽  
High Speed ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Video Camera ◽  
Sound Level ◽  
Lawn Mower ◽  
Level Meter

When the airflow patterns inside a lawn mower deck are understood, the deck can be redesigned to be efficient and have an increased cutting ability. To learn more, a combination of computational and experimental studies was performed to investigate the effects of blade and housing designs on a flow pattern inside a1.1mwide corotating double-spindle lawn mower deck with side discharge. For the experimental portion of the study, air velocities inside the deck were measured using a laser Doppler velocimetry (LDV) system. A high-speed video camera was used to observe the flow pattern. Furthermore, noise levels were measured using a sound level meter. For the computational fluid dynamics (CFD) work, several arbitrary radial sections of a two-dimensional blade were selected to study flow computations. A three-dimensional, full deck model was also developed for realistic flow analysis. The computational results were then compared with the experimental results.

scholarly journals Experimental Investigation of Local Scour Protection for Cylindrical Bridge Piers Using Anti-Scour Collars

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1515 ◽  
Author(s):  
Shunyi Wang ◽  
Kai Wei ◽  
Zhonghui Shen ◽  
Qiqi Xiang
Keyword(s):  
Protective Effect ◽  
Local Scour ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Experimental Program ◽  
Design Parameters ◽  
External Diameter ◽  
River Sand ◽  
Bed Scour ◽  
Scour Protection

Local scour of bridge piers is one of the main threats responsible for bridge damage. Adopting scour countermeasures to protect bridge foundations from scour has become an important issue for the design and maintenance of bridges located in erodible sediment beds. This paper focuses on the protective effect of one active countermeasure named an “anti-scour collar” on local scour around the commonly used cylindrical bridge pier. A cylindrical pier model was set up in a current flume. River sand with a median particle size of 0.324 mm was selected and used as the sediment in the basin. A live-bed scour experimental program was carried out to study the protective effect of an anti-scour collar by comparing the local scour at a cylindrical bridge pier model with and without collar. The effects of three design parameters including collar installation height, collar external diameter and collar protection range, on the scour depth and scour development were investigated parametrically. According to the experimental results, it can be concluded that: the application of an anti-scour collar alleviates the local scour at the pier effectively; and the protection effect decreases with an increase in the collar installation height, but increases with an increase in the collar external diameter and the protection range. Design suggestions for improving the scour protective effect of the anti-scour collar are summarized and of great practical guiding significance to the development of anti-scour collars for bridge piers.

CFD Analysis of Cross Flow in Rod Bundles Under Rolling Motion

2016 ◽  
Author(s):  
Di Liu ◽  
Wenxi Tian ◽  
Suizheng Qiu ◽  
G. H. Su
Keyword(s):  
Flow Behavior ◽  
Three Dimensional ◽  
Cross Flow ◽  
Reynolds Stress Model ◽  
Momentum Equation ◽  
Rolling Motion ◽  
Cfd Analysis ◽  
Rod Bundles ◽  
Rolling Velocity ◽  
Dimensional Simulation

A CFD analysis of cross flow in rod bundles in rolling motion was performed to investigate the effect of rolling motion on the flow behavior between the subchannels. The rolling motion was assumed as a sinusoid. The additional forces due to the rolling motion including azimuthal force, centrifugal force and coriolis force were added into the source term in the momentum equation. A transient three dimensional simulation of square rod bundles model was performed in various rolling conditions. In order to precisely predict secondary flow patterns in rod bundles, Reynolds Stress Model was selected as the turbulent model. Effect of various rolling parameters such as rolling velocity and amplitude on the cross mixing was investigated. The results show that cross flow is strongly affected by the rolling motion. The local cross flow field in rolling motion was showed in detail. Also, the mixing coefficients based on CFD results were calculated. Empirical correlations of turbulent mixing were modified to consider the effect of rolling conditions, which can be used in the traditional subchannel thermal hydraulic code.

Numerical Simulation of Polymer Flows in Coat-Hanger Die Using Wagner Constitutive Model

2011 ◽  
Vol 189-193 ◽  
pp. 1941-1945
Author(s):  
Yong Li ◽  
Jian Rong Zheng
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Constitutive Model ◽  
Numerical Solutions ◽  
Flow Behavior ◽  
Computing Time ◽  
Three Dimensional ◽  
Die Design ◽  
Dimensional Simulation ◽  
Element Method

An understanding of flow behavior of polymer melts through a slit die is extremely important for optimizing die design. In this paper numerical simulations have been undertaken for the flow of linear low-density polyethylene through Coat-hanger sheet dies. A new finite element method is proposed to simulate the flow in slit channel using Wagner constitutive model. This is one kind of finite element semi-analytical method by which the velocity distributions in thickness direction is approach by Fourier series. Numerical results of volumetric flow and pressure in coat-hanger dies are given to compare to the three-dimensional simulation using the finite element method. It appears that numerical solutions are as accurate as the complete 3D calculations and the computing time can be saved.

scholarly journals Analysis of Hydrodynamics of Fluid Flow on Corrugated Sheets of Packing

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Kumar Subramanian ◽  
Günter Wozny
Keyword(s):  
Flow Behavior ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Elementary Geometry ◽  
Ansys Fluent ◽  
Vof Model ◽  
Corrugated Sheets ◽  
Wetted Area ◽  
Icem Cfd ◽  
Good Agreement

Modelling of the hydrodynamics behaviour of the liquid on the corrugated sheets of packing is studied using three-dimensional, volume-of-fluid (VOF) model that is incorporated in Ansys Fluent 12.0. The flow of three different liquids with different physical properties is modelled. A domain of corrugated sheets of packing resembling the real structured packing with little modifications in the elementary geometry is constructed using ICEM CFD 12.0. The quantitative comparisons of the wetting behavior from the simulations are in good agreement with experiments. Further, the study has been extended to understand the influence of the second corrugated sheet on the flow behavior. The contours from the simulations indicate the liquid hold-up in the crimp of two corrugated sheets, and these results are in good agreement with the earlier experimental studies performed using X-ray tomography in the literature. The result from the simulation shows that even for the high flow rate of around 811 mL/min for silicon-oil (DC5), only 60% of the corrugated sheet has been wetted. Hence, the efficiency of the existing packing can be further increased by increasing the wetted area in the corrugated sheet of packing.

Three-dimensional numerical simulation of local scour in the vicinity of circular side-by-side bridge piers with ice cover

2020 ◽  
Author(s):  
Mohammad Reza Namaee ◽  
Jueyi Sui ◽  
Yongsheng Wu ◽  
Natalie Linklater
Keyword(s):  
Laboratory Experiments ◽  
Transport Model ◽  
Numerical Models ◽  
Three Dimensional ◽  
Ice Cover ◽  
Local Scour ◽  
Bridge Piers ◽  
Accurate Estimation ◽  
Scour Depth ◽  
Cold Regions

Local scour around piers is one of the primary causes of collapse of bridges that cross rivers. The most severe scouring occurs in cold regions where ice cover significantly changes the velocity profile. Having an accurate estimation of the maximum scour depth around bridge piers, especially in cold regions, is necessary for a safer design of piers. In this study, 3-D numerical models are compared to laboratory experiments to examine the process of local scour around bridge piers with and without smooth and rough ice cover. By using the equation of Meyer-Peter Müller, the sediment transport model is validated to approximate the transport of the sediment particles. Numerical results showed good agreements with experimental observations where the maximum scour depth and Turbulent Kinetic Energy (TKE) around bridge piers were the highest under rough ice cover conditions.

Numerical Analysis of Flow Behavior Inside the Blast Furnace

2009 ◽  
Author(s):  
Dong Fu ◽  
Fengguo Tian ◽  
Guoheng Chen ◽  
D. Frank Huang ◽  
Chenn Q. Zhou
Keyword(s):  
Blast Furnace ◽  
Gas Flow ◽  
Cfd Simulation ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Furnace Productivity ◽  
Gas Distribution ◽  
Furnace Shaft ◽  
Parametric Studies ◽  
Flow Through

Gas and burden distributions inside a blast furnace play an important role in optimizing gas utilization versus the furnace productivity and minimizing the CO2 emission in steel industries. In this paper, a mathematical model is presented to describe the burden descent in the blast furnace shaft and gas distribution, with the alternative structure of coke and ore layers being considered. Multi-dimensional Ergun’s equation is solved with considering the turbulent compressible gas flow through the burden column. The porosity of each material will be treated as a function of three dimensional functions which will be determined by the kinetics sub-models accordingly. A detailed investigation of gas flow through the blast furnace will be conducted with the given initial burden profiles along with the effects of redistribution during burden descending. Also, parametric studies will be carried out to analyze the gas distribution cross the blast furnace under different cohesive zone (CZ) shapes, charging rate, and furnace top pressure. A good agreement was obtained between the CFD simulation and published experimental data. Based on the results, the inverse V shape is proved to be the most desirable CZ profile.

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