scholarly journals Experimental Study on Extreme Hydrodynamic Loading on Pipelines. Part 1: Flow Hydrodynamics

2019 ◽  
Vol 7 (8) ◽  
pp. 251 ◽  
Author(s):  
Ghodoosipour ◽  
Stolle ◽  
Nistor ◽  
Mohammadian ◽  
Goseberg
Keyword(s):  
Flow Characteristics ◽  
Dam Break ◽  
Water Levels ◽  
Coastal Communities ◽  
Experimental Program ◽  
Flow Conditions ◽  
The Past ◽  
Hydrodynamic Loading ◽  
Extreme Flood ◽  
Dam Break Flow

Over the past two decades, extreme flood events generated by tsunamis or hurricanes have caused massive damage to nearshore infrastructures and coastal communities. Utility pipelines are part of such infrastructure and need to be protected against potential extreme hydrodynamic loading. Therefore, to address the uncertainties and parameters involved in extreme hydrodynamic loading on pipelines, a comprehensive experimental program was performed using an experimental facility which is capable of generating significant hydraulic forcing, such as dam-break waves. The study presented herein examines the dam-break flow characteristics and influence of the presence of pipelines on flow conditions. To simulate conditions of coastal flooding under tsunami-induced inundation, experiments were performed on both dry and wet bed conditions to assess the influence of different impoundment depths and still water levels on the hydrodynamic features.

Experimental and SPH studies of reciprocal wet-bed dam-break flow over obstacles

2021 ◽  
pp. 2150098
Author(s):  
Armin Ansari ◽  
Ehsan Khavasi ◽  
Jafar Ghazanfarian
Keyword(s):  
Surface Deformation ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Dam Break ◽  
Experimental Results ◽  
Mesh Free ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Dam Break Flow ◽  
Velocity Effect

Different permutations of the single and the two-fold dam-break flow have been investigated using the mesh-free smoothed-particle hydrodynamics and the experimental setup. The free-surface deformation in the case with the wet bed for five different downstream water heights has been investigated and respective numerical and experimental results were presented. The results demonstrate that the increase of the water height over the wet bed leads to the reduction of the flow front velocity. Effect of considering or omitting the dam gate during the numerical simulation has also been examined, which proves that the simulations including the dam gate show improved agreement with the experimental results. Influence of the three-dimensional cubic, triangular, circular and square cylindrical obstacles and their position on flow characteristics has been investigated. As the distance between the triangular obstacle and the gate increases, a bore is created at the position closer to the top of the triangle. In addition, it is found that larger force is exerted on the circular cylinder in comparison to the square cylinder.

scholarly journals Application of a 3-D CFD model to investigate flood-related engineering problems

2018 ◽  
Vol 40 ◽  
pp. 06004
Author(s):  
Daniel Horna Munoz ◽  
George Constantinescu
Keyword(s):  
Dam Break ◽  
Low Flow ◽  
Practical Application ◽  
Flow Conditions ◽  
Validation Data ◽  
Channel Bend ◽  
Engineering Problems ◽  
Dam Break Flow ◽  
Flooded Area ◽  
Critical Regions

The paper discusses the application of a fully 3-D, non-hydrostatic, RANS model with deformable free-surface capabilities to several main types of flood-related engineering problems. The model is found to accurately simulate the dam break flow developing in a 900 open channel bend for which detailed validation data from a laboratory experiment are available. First practical application deals with mitigation of flooding extent via implementation of flood protection structures such as floodwalls. Numerical results show that the floodwalls effectively protect the critical regions situated in the vicinity of the river and the reduction of the flooded area with respect to the case when floodwalls are not present is about the same at high-flow conditions and at low-flow conditions. The second application deals with prediction of flow structure around a location containing a bridge whose deck becomes submerged as the flood wave passes the bridge location. The final application considers the effects of a sudden dam break failure for a dam situated upstream of the Iowa City, USA.

The Study of Flow Characteristics of Newtonian and Power-Law Non-Newtonian Fluids by Dam-Break Flow Model

2015 ◽  
Vol 802 ◽  
pp. 51-56 ◽  
Author(s):  
Puay How Tion ◽  
Abdullah Faiz ◽  
Nor Azazi Zakaria ◽  
Hosoda Takashi
Keyword(s):  
Power Law ◽  
Flow Characteristics ◽  
Flow Region ◽  
Dam Break ◽  
Newtonian Fluids ◽  
Flow Equations ◽  
Numerical Studies ◽  
Front Position ◽  
Dam Break Flow ◽  
Volume Of Fluids

The study aims to investigate the flow characteristics of Newtonian and power-law non Newtonian fluids by using the dam-break of finite extent problem. Analytical and numerical studies are carried out to clarify the flow characteristics. In the analytical study, shallow flow equations are used to derive the characteristic in the viscous flow region for both the Newtonian and power-law non-Newtonian fluids. A numerical model based on the Volume of Fluids (VOF) method with higher order numerical scheme is used to verify the analytical findings. The study derived the flow characteristics based on the propagation of front position and the attenuation of flow depth at the dam upstream boundary.

Investigation of Dam-Break Flow Over Abruptly Contracting Channel With Trapezoidal-Shaped Lateral Obstacles

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Hatice Ozmen-Cagatay ◽  
Selahattin Kocaman
Keyword(s):  
Numerical Models ◽  
Rectangular Cross Section ◽  
Dam Break ◽  
Water Levels ◽  
Navier Stokes ◽  
Video Images ◽  
Dam Break Flow ◽  
Downstream Section ◽  
Surface Profiles ◽  
Good Agreement

The present paper aims to investigate the dam-break flow over dry channel with an abrupt contracting part in certain downstream section. A new experiment was carried out in a smooth-prismatic channel with rectangular cross section and horizontal bed. A digital imaging technique was adopted for flow measurement and thus flood wave propagation was sensitively obtained. Synchronous filmed images of the dam-break flow were nonintrusively acquired with three cameras, through glass sidewalls of the channel. Free surface profiles and time evolution of water levels were derived directly from the recorded video images using virtual wave probe without disturbing the flow. Furthermore, the present study highlights the formation and propagation of the negative bore due to abruptly contracting channel. The measured results were compared with the numerical solution of Reynolds averaged Navier–Stokes (RANS) equations with k-ε turbulence model and good agreement was achieved. New experimental data can be useful for scientific community to validate numerical models.

scholarly journals TRANSIENT DAM-BREAK WAVE LOADING ON PIPELINES NEAR SLOPING BED

2020 ◽  
pp. 55
Author(s):  
Behnaz Ghodoosipour ◽  
Tomoyuki Takabatake ◽  
Ioan Nistor ◽  
Majid Mohammadian ◽  
Go Hamano ◽  
...  
Keyword(s):  
Experimental Research ◽  
Extreme Events ◽  
Coastal Areas ◽  
Dam Break ◽  
Experimental Program ◽  
Wave Loading ◽  
Comprehensive Understanding ◽  
Changing Climate ◽  
Hydrodynamic Loading ◽  
Sloping Bed

Extreme events such as tsunamis and floods have caused massive damaging consequences to nearshore infrastructures. This has been more significant recently due to a changing climate. Transmission pipelines are among such infrastructures and need to be protected against potential extreme events. Design of pipelines requires comprehensive understanding of the exerting hydrodynamic forces. Such pipelines are often placed on sloping beds in coastal areas. Therefore, to address the uncertainties and parameters involved in extreme hydrodynamic loading on pipelines near sloping bed, an experimental program was conducted at the hydraulic laboratory in WASEDA University, Tokyo, Japan. This study is a complement of another experimental research conducted by Ghodoosipour et al., 2019a and b to investigate loadings from tsunami-like dam-break waves on pipelines located on flat bed.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/y6nSfe34SAw

scholarly journals Experimental and Numerical Analysis of a Dam-Break Flow through Different Contraction Geometries of the Channel

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1124 ◽  
Author(s):  
Selahattin Kocaman ◽  
Hasan Güzel ◽  
Stefania Evangelista ◽  
Hatice Ozmen-Cagatay ◽  
Giacomo Viccione
Keyword(s):  
Wave Propagation ◽  
Numerical Models ◽  
Rectangular Channel ◽  
Dam Break ◽  
Water Levels ◽  
Experimental Results ◽  
Complex Flow ◽  
Related Field ◽  
Dam Break Flow ◽  
Irregular Topography

Dam-break wave propagation usually occurs over irregular topography, due for example to natural contraction-expansion of the river bed and to the presence of natural or artificial obstacles. Due to limited available dam-break real-case data, laboratory and numerical modeling studies are significant for understanding this type of complex flow problems. To contribute to the related field, a dam-break flow over a channel with a contracting reach was investigated experimentally and numerically. Laboratory tests were carried out in a smooth rectangular channel with a horizontal dry bed for three different lateral contraction geometries. A non-intrusive digital imaging technique was utilized to analyze the dam-break wave propagation. Free surface profiles and time variation of water levels in selected sections were obtained directly from three synchronized CCD video camera records through a virtual wave probe. The experimental results were compared against the numerical solution of VOF (Volume of Fluid)-based Shallow Water Equations (SWEs) and Reynolds-Averaged Navier-Stokes (RANS) equations with the k-ε turbulence model. Good agreements were obtained between computed and measured results. However, the RANS solution shows a better correspondence with the experimental results compared with the SWEs one. The presented new experimental data can be used to validate numerical models for the simulation of dam-break flows over irregular topography.

scholarly journals Stochastic Uncertainty in a Dam-Break Experiment with Varying Gate Speeds

2021 ◽  
Vol 9 (1) ◽  
pp. 67
Author(s):  
Hiroshi Takagi ◽  
Fumitaka Furukawa
Keyword(s):  
High Speed ◽  
Pressure Sensors ◽  
Dam Break ◽  
Maximum Pressure ◽  
Vertical Acceleration ◽  
Ship Wakes ◽  
Dam Break Flow ◽  
Statistical Relationships ◽  
Flow Propagation ◽  
Impulsive Pressure

Uncertainties inherent in gate-opening speeds are rarely studied in dam-break flow experiments due to the laborious experimental procedures required. For the stochastic analysis of these mechanisms, this study involved 290 flow tests performed in a dam-break flume via varying gate speeds between 0.20 and 2.50 m/s; four pressure sensors embedded in the flume bed recorded high-frequency bottom pressures. The obtained data were processed to determine the statistical relationships between gate speed and maximum pressure. The correlations between them were found to be particularly significant at the sensors nearest to the gate (Ch1) and farthest from the gate (Ch4), with a Pearson’s coefficient r of 0.671 and −0.524, respectively. The interquartile range (IQR) suggests that the statistical variability of maximum pressure is the largest at Ch1 and smallest at Ch4. When the gate is opened faster, a higher pressure with greater uncertainty occurs near the gate. However, both the pressure magnitude and the uncertainty decrease as the dam-break flow propagates downstream. The maximum pressure appears within long-period surge-pressure phases; however, instances considered as statistical outliers appear within short and impulsive pressure phases. A few unique phenomena, which could cause significant bottom pressure variability, were also identified through visual analyses using high-speed camera images. For example, an explosive water jet increases the vertical acceleration immediately after the gate is lifted, thereby retarding dam-break flow propagation. Owing to the existence of sidewalls, two edge waves were generated, which behaved similarly to ship wakes, causing a strong horizontal mixture of the water flow.

A three dimensional dam break flow: Small time behavior

2021 ◽  
Vol 110 ◽  
pp. 102583
Author(s):  
Elona Fetahu ◽  
Oguz Yilmaz
Keyword(s):  
Three Dimensional ◽  
Small Time ◽  
Dam Break ◽  
Time Behavior ◽  
Dam Break Flow

scholarly journals Investigate Impact Force of Dam-Break Flow against Structures by Both 2D and 3D Numerical Simulations

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 344
Author(s):  
Le Thi Thu Hien ◽  
Nguyen Van Chien
Keyword(s):  
Impact Force ◽  
Numerical Models ◽  
Splitting Method ◽  
Dam Break ◽  
Navier Stokes ◽  
Dynamic Force ◽  
Exact Mass ◽  
Initial Water ◽  
Dam Break Flow ◽  
2D And 3D

The aim of this paper was to investigate the ability of some 2D and 3D numerical models to simulate flood waves in the presence of an isolated building or building array in an inundated area. Firstly, the proposed 2D numerical model was based on the finite-volume method (FVM) to solve 2D shallow-water equations (2D-SWEs) on structured mesh. The flux-difference splitting method (FDS) was utilized to obtain an exact mass balance while the Roe scheme was invoked to approximate Riemann problems. Secondly, the 3D commercially available CFD software package was selected, which contained a Flow 3D model with two turbulent models: Reynolds-averaged Navier-Stokes (RANs) with a renormalized group (RNG) and a large-eddy simulation (LES). The numerical results of an impact force on an obstruction due to a dam-break flow showed that a 3D solution was much better than a 2D one. By comparing the 3D numerical force results of an impact force acting on building arrays with the existence experimental data, the influence of velocity-induced force on a dynamic force was quantified by a function of the Froude number and the water depth of the incident wave. Furthermore, we investigated the effect of the initial water stage and dam-break width on the 3D-computed results of the peak value of force intensity.

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