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.

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 Experimental and Numerical Investigation of 3D Dam-Break Wave Propagation in an Enclosed Domain with Dry and Wet Bottom

2021 ◽  
Vol 11 (12) ◽  
pp. 5638
Author(s):  
Selahattin Kocaman ◽  
Stefania Evangelista ◽  
Hasan Guzel ◽  
Kaan Dal ◽  
Ada Yilmaz ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Numerical Models ◽  
Three Dimensional ◽  
Dam Break ◽  
Dam Failure ◽  
Navier Stokes ◽  
Negative Wave ◽  
Through Flow ◽  
Instantaneous Removal ◽  
Surface Patterns

Dam-break flood waves represent a severe threat to people and properties located in downstream regions. Although dam failure has been among the main subjects investigated in academia, little effort has been made toward investigating wave propagation under the influence of tailwater depth. This work presents three-dimensional (3D) numerical simulations of laboratory experiments of dam-breaks with tailwater performed at the Laboratory of Hydraulics of Iskenderun Technical University, Turkey. The dam-break wave was generated by the instantaneous removal of a sluice gate positioned at the center of a transversal wall forming the reservoir. Specifically, in order to understand the influence of tailwater level on wave propagation, three tests were conducted under the conditions of dry and wet downstream bottom with two different tailwater depths, respectively. The present research analyzes the propagation of the positive and negative wave originated by the dam-break, as well as the wave reflection against the channel’s downstream closed boundary. Digital image processing was used to track water surface patterns, and ultrasonic sensors were positioned at five different locations along the channel in order to obtain water stage hydrographs. Laboratory measurements were compared against the numerical results obtained through FLOW-3D commercial software, solving the 3D Reynolds-Averaged Navier–Stokes (RANS) with the k-ε turbulence model for closure, and Shallow Water Equations (SWEs). The comparison achieved a reasonable agreement with both numerical models, although the RANS showed in general, as expected, a better performance.

2D and 3D Unsteady Flow in Squirrel-Cage Centrifugal Fan and Aeroacoustic Behavior

2006 ◽  
Author(s):  
M. Younsi ◽  
F. Bakir ◽  
S. Kouidri ◽  
R. Rey
Keyword(s):  
Unsteady Flow ◽  
Numerical Models ◽  
Pressure Fluctuations ◽  
Internal Flow ◽  
Navier Stokes ◽  
Computational Domain ◽  
Centrifugal Fan ◽  
Geometry Modeling ◽  
3D Unsteady Flow ◽  
2D And 3D

The objective of this paper is the study and the analysis of the complex phenomena related to the internal flow in a centrifugal fan, using Computational Fluid Dynamics (CFD) tools, completed with experimental investigation in order to validate the used numerical models. The CFD analysis concerns 2D and 3D unsteady flow. The studied phenomena are the interactions and unsteadiness induced by the motion of the rotating blades relatively to the volute and their impact on the aeroacoustic behavior of the fan. Thus, 3D and 2D unsteady calculations using Unsteady Reynolds Averaged Navier Stokes (URANS) approach has been applied on a hybrid mesh grid whose refinement has been studied and adapted to the flow morphology. Turbulence has been modeled with the k-ω-Shear Stress Model (SST) model. The computational domain has been divided into two zones, a rotating zone including the impeller and stationary zone including the volute. A sliding mesh technique has been applied to the interfaces in order to allow the unsteady interactions between the two zones. The overall performances predicted by the computations have been validated at different flow rate. For each geometry modeling (2D and 3D), the unsteady part of the study is illustrated by analyzing the pressure fluctuations on different points from the lateral surface of the volute. The analysis of the wake generated by the rotation of the blower shows that the volute tongue is the main zone of unsteadiness and flow perturbations. In order to predict the acoustic pressures, the unsteady flow field variables provided by the CFD calculations have been used as inputs in the Ffowks Williams-Hawkings equations.

scholarly journals Numerical Study of 2D and 3D Separation Phenomena in the Dam-Break Flow Interacting with a Triangular Obstacle

2016 ◽  
Vol 60 (3) ◽  
pp. 159-166 ◽  
Author(s):  
Alexander Khrabry ◽  
◽  
Evgueni Smirnov ◽  
Dmitry Zaytsev ◽  
Valery Goryachev ◽  
...  
Keyword(s):  
Numerical Study ◽  
Dam Break ◽  
Dam Break Flow ◽  
2D And 3D

Simulations of Dam-Break Flows Using Free Surface Capturing Method

2008 ◽  
Vol 24 (4) ◽  
pp. 391-403 ◽  
Author(s):  
W.-Y. Chang ◽  
L.-C. Lee ◽  
H.-C. Lien ◽  
J.-S. Lai
Keyword(s):  
Free Surface ◽  
Stokes Equations ◽  
Variable Density ◽  
Dam Break ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow Equations ◽  
Weakly Compressible ◽  
Dam Break Flow ◽  
Free Surface Capturing

AbstractA model adopting the surface capturing method is developed for the simulation of dam-break flows by solving the Navier-Stokes equations of weakly compressible and variable density flows in open channels. Due to the characteristics of weakly compressible flow equations, a compressibility parameter describing the compressibility of fluid is determined to obtain the time-accurate flow fields in both liquid and gas regions simultaneously. Accordingly, the location of free surface can be captured as a discontinuity of the density field for dam-break flow simulations. The numerical algorithm in the proposed method is based on the framework of the finite volume method for discretization in space. To deal with the discontinuity property of fluid density near the free surface, the TVD-MUSCL scheme is adopted to overcome numerical oscillations and dissipation. For discretization in time, the explicit 4-stage Runge-Kutta scheme is employed in the model. Finally, several typical dam-break flow problems in open channel are simulated to demonstrate the validation and applicability of the proposed model.

scholarly journals CFD modelling approach for dam break flow studies

2009 ◽  
Vol 6 (6) ◽  
pp. 6759-6793 ◽  
Author(s):  
C. Biscarini ◽  
S. Di Francesco ◽  
P. Manciola
Keyword(s):  
Shallow Water ◽  
Three Dimensional ◽  
Free Surface Flows ◽  
Dam Break ◽  
Navier Stokes ◽  
Cfd Modelling ◽  
Wave Celerity ◽  
Dam Break Flow ◽  
Complete Set ◽  
First Time

Abstract. This paper presents numerical simulations of free surface flows induced by a dam break comparing the shallow water approach to fully three-dimensional simulations. The latter are based on the solution of the complete set of Reynolds-Averaged Navier-Stokes (RANS) equations coupled to the Volume of Fluid (VOF) method. The methods assessment and comparison are carried out on a dam break over a flat bed without friction and a dam break over a triangular bottom sill. Experimental and numerical literature data are compared to present results. The results demonstrate that the shallow water approach loses some three-dimensional phenomena, which may have a great impact when evaluating the downstream wave propagation. In particular, water wave celerity and water depth profiles could be underestimated due to the incorrect shallow water idealization that neglects the three-dimensional aspects due to the gravity force, especially during the first time steps of the motion.

scholarly journals 2D Shallow Water Model for Dam Break and Column Interactions

2020 ◽  
Vol 6 (3) ◽  
pp. 237
Author(s):  
Putu Indah Dianti Putri ◽  
Rifqi Fauzan Iskandar ◽  
Mohammad Bagus Adityawan ◽  
Hadi Kardhana ◽  
Dian Indrawati
Keyword(s):  
Shallow Water ◽  
Numerical Scheme ◽  
Dam Break ◽  
Water Model ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Navier Stokes Equation ◽  
Saint Venant Equations ◽  
Dam Break Flow ◽  
Analytic Models

Dam break causes disastrous effects on the surrounding area, especially at the downstream, therefore, there is a need for accurate and timely predictions of dam break propagation to prevent both property damage and loss of life. This study aimed to determine the movement of dam-break flow in the downstream area by solving the Shallow Water Equations (SWE) or Saint Venant Equations which are based on the conservation of mass and momentum derived from Navier Stokes equation. The model was generated using a finite difference scheme which is the most common and simplest method for dam-break modeling while Forward Time Central Space (FTCS) numerical scheme was applied to simulate two-dimensional SWE. Moreover, the accuracy of the numerical model was checked by comparing its results with the analytic results of one-dimensional cases and a relatively small value of error was found in comparison to the analytic models as indicated with the RMSE values close to 0. The numerical to the two-dimensional models were also compared to a simple dam break in a flume and dam break with column interactions and the wave propagation in both cases was observed to become very close at a certain time.  The model, however, used numerical filter (Hansen) to reduce the oscillations or numerical instability. The simulation and analysis, therefore, showed the ability of the numerical scheme of FTCS to resolve both cases of the simple dam break and dam break with column interactions in the Two-dimensional Shallow Water. 

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 Study of dam break flow interaction with urban settlements over a sloping channel

2018 ◽  
Vol 40 ◽  
pp. 06006
Author(s):  
Ioanna Stamataki ◽  
Jun Zang ◽  
Eugeny Buldakov ◽  
Thomas Kjeldsen ◽  
Dimitris Stagonas
Keyword(s):  
Water Depth ◽  
Extreme Events ◽  
Computational Models ◽  
Dam Break ◽  
Turbulent Model ◽  
Initial Water ◽  
Complete Dataset ◽  
Urban Settlements ◽  
Time Histories ◽  
Dam Break Flow

This paper describes a dam break experiment on a sloped channel, carried out in a hydraulic flume at UCL for the purpose of computer model validations of extreme events, such as flash floods. An elevated reservoir was situated upstream followed by a 1/20 slope leading up to a flat floodplain. Plexiglas blocks were positioned on the floodplain constituting different urban settlements and creating different obstructions to the flow. The flume was instrumented along its length measuring the change in water depth in the reservoir; the water depth time histories in various locations; the flow patterns and flood front velocity; and lastly the pressure and load on the buildings. The experiments were repeated for different urban settlements, flood intensities (two different initial water depths in the reservoir) and roughness layers along the slope, representative of a vegetated and a non-vegetated hill. In the present study, the experimental results were described qualitatively and compared with theoretical processes and 2D numerical results obtained using OpenFOAM's RAS turbulent model. Water depth, velocity and load measurements were analysed for different cases and it was found that while the 2D model provided a good fit on the slope, the flows generated around the building were more complex 3D formations which lead to inaccuracies. All experiments were repeated multiple times to ensure repeatability and thus the procedure was validated successfully providing a complete dataset that can be used for the validation of computational models for extreme events.

scholarly journals On sediment transport under dam-break flow

2002 ◽  
Vol 473 ◽  
pp. 265-274 ◽  
Author(s):  
DAVID PRITCHARD ◽  
ANDREW J. HOGG
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Numerical Models ◽  
Sediment Concentration ◽  
Transport Processes ◽  
Dam Break ◽  
Suspended Sediment Transport ◽  
Test Bed ◽  
Small Depth ◽  
Dam Break Flow

We present exact solutions for suspended sediment transport under one-dimensional dam-break flow, both over a dry bed and into a small depth of tail water. We explicitly calculate the suspended sediment concentration, including erosion and deposition, and investigate the effect of varying the erosional and depositional models employed. These solutions order insight into sediment transport processes under floods or sheet flow events, and we also discuss their application as test-bed solutions for the validation of numerical models.

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