Research on dam-break flow induced front wave impacting a vertical wall based on the CLSVOF and level set methods

2019 ◽  
Vol 178 ◽  
pp. 442-462 ◽  
Author(s):  
Y.L. Li ◽  
C.H. Yu
Keyword(s):  
Level Set ◽  
Vertical Wall ◽  
Level Set Methods ◽  
Dam Break ◽  
Dam Break Flow

scholarly journals Kinematic and dynamic analysis of dam break flow impact on vertical walls using weakly compressible SPH

2021 ◽  
Vol 15 (2) ◽  
Author(s):  
Petr Jančík ◽  
Tomáš Hyhlík
Keyword(s):  
Dynamic Analysis ◽  
Evaluation Method ◽  
Numerical Solutions ◽  
Vertical Wall ◽  
Dam Break ◽  
Column Height ◽  
Width Ratio ◽  
Total Force ◽  
Dam Break Flow ◽  
The Impact

This article presents the kinematic and dynamic analysis of a dam break flow based on data obtained from numerical solutions by the smoothed particle hydrodynamics (SPH) method. The method and original algorithms necessary for correct pressure evaluation are thoroughly described. The pressure evaluation method consists of data reading using virtual sensors and filtration in the time domain using the weight function. A simple convergence study showing the independency of the evaluated parameters of spatial resolution is presented together with validation of the introduced methods and algorithms using a simple hydrostatic problem and experimental data available in the literature. We focus on two parameters that describe the problem: distance of the downstream vertical wall from the edge of the liquid column and the column’s height to width ratio. We found that the impact can be divided into three consecutive phases characterized by specific kinematic (flow patterns) and dynamic (exerted pressure and forces) behavior and different roles of the investigated parameters during these phases. During the early stages of an impact, the column’s distance from the vertical wall plays a major role. A dependency between the column distance and the force peak in this stage was identified in the form of a power function. In the second stage, when a rolling wave emerges, the vertical wall position influences the shape of the wave and the pressure distribution on the wall. The total force is greater in this phase for lower column height to width ratios due to the higher total momentum of the liquid. In the third stage, when the rolling wave impacts the liquid surface, the employed methodology with two-dimensional solution and free-surface approach seems to reach its limits of applicability. A more complex modelling would be necessary to capture this phase of the impact properly.

Numerical and experimental investigation of three-dimensionality in the dam-break flow against a vertical wall

2018 ◽  
Vol 30 (4) ◽  
pp. 682-693 ◽  
Author(s):  
Mohamed M. Kamra ◽  
Nik Mohd ◽  
Cheng Liu ◽  
Makoto Sueyoshi ◽  
Changhong Hu
Keyword(s):  
Experimental Investigation ◽  
Vertical Wall ◽  
Dam Break ◽  
Dam Break Flow

scholarly journals RELATIONSHIPS BETWEEN FLUID MOTION AND PRESSURE VARIATION BY DAM-BREAK FLOWS COLLIDING WITH VERTICAL WALL

2018 ◽  
pp. 10
Author(s):  
Natsuki Mizutani ◽  
Jinji Umeda
Keyword(s):  
Tsunami Wave ◽  
Vertical Wall ◽  
Fluid Motion ◽  
Tohoku Earthquake ◽  
Wave Force ◽  
Pressure Variation ◽  
Dam Break ◽  
The 2011 Tohoku Earthquake ◽  
Dam Break Flow ◽  
Hazard Area

The 2011 Tohoku Earthquake Tsunami ran up the height of over 40 m and covered over 560 km2 of the coastal land area in Tohoku, Japan. The tsunami destroyed many structures and killed over 15,000 people. Appropriate measures should be taken against the next giant tsunami to avoid such tragedy. The generation mechanism of wave force is uncertain when a tsunami wave running on land collides with a structure. Especially, the fluid motion of a tip of tsunami wave immediately after the collision with a structure is very complicated. The information of the pressure distribution acting on the structure is necessary to construct buildings in the coastal hazard area. The purpose of this study is to clarify the relationships between the fluid motion and pressure variation by a dam-break flow as a tsunami flow on a dry bed colliding with structures.

Application of Level Set / Immersed-Boundary Method to Simulate Fluid-Fluid and Fluid-Solid Problems

2011 ◽  
Author(s):  
C. H. Yu ◽  
Tony W. H. Sheu
Keyword(s):  
Level Set ◽  
Immersed Boundary Method ◽  
Complex Structure ◽  
Finite Thickness ◽  
Level Set Methods ◽  
Immersed Boundary ◽  
Advection Equation ◽  
Boundary Method ◽  
Seventh Order ◽  
Dam Break Flow

Free surface generated by a complex structure will be predicted in Cartesian grids by our proposed approach, which combines the immersed boundary and level set methods to model the solid-fluid and fluid-fluid interface, respectively. For accurately predicting the level set value, the spatial derivative terms in the pure advection equation are approximated by the seventh-order accurate upwinding combined compact difference scheme. For ensuring that the predicted interface has a finite thickness all the time, the re-initialization equation is used. In the immersed boundary method we proposed a differential based interpolation scheme at points near the solid boundaries. The discretized linear system of Poisson pressure equation is solved using the DFC (Divergence free compensated) method. Dam-break flow at the Reynolds number Re = 42792 is modeled to get the results that agree well with the experiment data. For the verification of the level set / immersed boundary method, water column collapsed over a submerged structure is also investigated.

EXPERIMENTAL AND THEORETICAL STUDY ON FLOOD BORE PROPAGATION AND MUSHROOM JET GENERATION OF DAM-BREAK FLOW

2011 ◽  
Vol 1 (3) ◽  
Author(s):  
H. H. Hwung ◽  
Ray Yang ◽  
Y. C. Tie ◽  
W.Y. Hsu ◽  
P. C. Kuo ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Dam Break ◽  
Dam Break Flow

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.

scholarly journals On the Relationship between Variational Level Set-Based and SOM-Based Active Contours

2015 ◽  
Vol 2015 ◽  
pp. 1-19 ◽  
Author(s):  
Mohammed M. Abdelsamea ◽  
Giorgio Gnecco ◽  
Mohamed Medhat Gaber ◽  
Eyad Elyan
Keyword(s):  
Level Set ◽  
Active Contour ◽  
Active Contours ◽  
Level Set Methods ◽  
Energy Functional ◽  
Self Organizing Maps ◽  
Complex Shapes ◽  
Variational Level Set ◽  
Preservation Property ◽  
The Relationship

Most Active Contour Models (ACMs) deal with the image segmentation problem as a functional optimization problem, as they work on dividing an image into several regions by optimizing a suitable functional. Among ACMs, variational level set methods have been used to build an active contour with the aim of modeling arbitrarily complex shapes. Moreover, they can handle also topological changes of the contours. Self-Organizing Maps (SOMs) have attracted the attention of many computer vision scientists, particularly in modeling an active contour based on the idea of utilizing the prototypes (weights) of a SOM to control the evolution of the contour. SOM-based models have been proposed in general with the aim of exploiting the specific ability of SOMs to learn the edge-map information via their topology preservation property and overcoming some drawbacks of other ACMs, such as trapping into local minima of the image energy functional to be minimized in such models. In this survey, we illustrate the main concepts of variational level set-based ACMs, SOM-based ACMs, and their relationship and review in a comprehensive fashion the development of their state-of-the-art models from a machine learning perspective, with a focus on their strengths and weaknesses.

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