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.

scholarly journals Smoothed Particle Hydrodynamics Modeling with Advanced Boundary Conditions for Two-Dimensional Dam-Break Floods

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1142
Author(s):  
Domenica Mirauda ◽  
Raffaele Albano ◽  
Aurelia Sole ◽  
Jan Adamowski
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Numerical Solutions ◽  
Vertical Wall ◽  
Dam Break ◽  
Secondary Wave ◽  
Two Dimensional ◽  
Boundary Treatment ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

To simulate the dynamics of two-dimensional dam-break flow on a dry horizontal bed, we use a smoothed particle hydrodynamics model implementing two advanced boundary treatment techniques: (i) a semi-analytical approach, based on the computation of volume integrals within the truncated portions of the kernel supports at boundaries and (ii) an extension of the ghost-particle boundary method for mobile boundaries, adapted to free-slip conditions. The trends of the free surface along the channel, and of the impact wave pressures on the downstream vertical wall, were first validated against an experimental case study and then compared with other numerical solutions. The two boundary treatment schemes accurately predicted the overall shape of the primary wave front advancing along the dry bed until its impact with the downstream vertical wall. Compared to data from numerical models in the literature, the present results showed a closer fit to an experimental secondary wave, reflected by the downstream wall and characterized by complex vortex structures. The results showed the reliability of both the proposed boundary condition schemes in resolving violent wave breaking and impact events of a practical dam-break application, producing smooth pressure fields and accurately predicting pressure and water level peaks.

Investigations of Reduction Effect of Vertical Wall on Dam-Break-Simulated Tsunami Surge Exerted on Wharf Piles

2018 ◽  
Vol 12 (02) ◽  
pp. 1840006 ◽  
Author(s):  
Cheng Chen ◽  
Bruce W. Melville ◽  
N. A. K. Nandasena
Keyword(s):  
High Speed ◽  
Preliminary Investigation ◽  
Vertical Wall ◽  
Pressure Sensors ◽  
Time History ◽  
Dam Break ◽  
Reservoir System ◽  
Reduction Effect ◽  
The Impact ◽  
Surge Height

For a preliminary investigation of the impact of a tsunami surge on wharf piles, a tsunami flume was built in a laboratory, and a dam break flow was generated by a gate-reservoir system to simulate a tsunami surge. In addition, a vertical wall was installed in front of the wharf model so that its effect in reducing tsunami load could be studied. Five different tsunami surge strengths were generated by this gate-reservoir system. Wave transducers were used in the test flume to capture surge heights and velocities, and hence the surge front profiles, for different surge strengths. High-speed video cameras (210 frames per second) were used to record the flow motion of the tsunami surge, and pressure sensors (1000[Formula: see text]Hz in frequency) were used to capture the time histories of the tsunami pressure on the wharf piles. Four stages of tsunami surge motions were observed by this high-speed camera. Accordingly, the pressure time history can be divided into three phases. In our experimental range, pressures were influenced by surge height and wall height, but not by the wall position. Based on the dimensionless experimental data (pile heights, surge heights, vertical wall heights, and surge pressures), equations for estimating tsunami loads on wharf pile are proposed, expressing surge front (peak impact) pressure and quasi-steady pressure as functions of surge height, wall height, and pile height.

scholarly journals Hydroelasticity effects on water-structure impacts

2020 ◽  
Vol 61 (9) ◽  
Author(s):  
T. Mai ◽  
C. Mai ◽  
A. Raby ◽  
D. M. Greaves
Keyword(s):  
Vertical Wall ◽  
Water Structure ◽  
Rigid Wall ◽  
Total Force ◽  
Impact Loads ◽  
Wave Impact ◽  
Impact Forces ◽  
Elastic Wall ◽  
Vertical Walls ◽  
The Impact

Abstract Local and global loadings, which may cause the local damage and/or global failure and collapse of offshore structures and ships, are experimentally investigated in this study. The research question is how the elasticity of the structural section affects loading during severe environmental conditions. Two different experiments were undertaken in this study to try to answer this question: (i) vertical slamming impacts of a square flat plate, which represents a plate section of the bottom or bow of a ship structure, onto water surface with zero degree deadrise angle; (ii) wave impacts on a truncated vertical wall in water, where the wall represents a plate section of a hull. The plate and wall are constructed such that they can be either rigid or elastic by virtue of a specially designed spring system. The experiments were carried out in the University of Plymouth’s COAST Laboratory. For the cases considered here, elasticity of the impact plate and/or wall has an effect on the slamming and wave impact loads. Here the slamming impact loads (both pressure and force) were considerably reduced for the elastic plate compared to the rigid one, though only at high impact velocities. The total impact force on the elastic wall was found to reduce for the high aeration, flip-through and slightly breaking wave impacts. However, the impact pressure decreased on the elastic wall only under flip-through wave impact. Due to the elasticity of the plates, the impulse of the first positive phase of pressure and force decreases significantly for the vertical slamming impact tests. This significant effect of hydroelasticity is also found for the total force impulse on the vertical wall under wave impacts. Graphic abstract Hydroelasticity effects on water-structure impacts: a impact pressures on dropped plates; b impact forces on dropped plates; c, d, e, f wave impact pressures on the vertical walls; g wave impact forces on the vertical walls; h wave force impulses on the vertical walls: elastic wall 1 vs. rigid wall (filled markers); elastic wall 2 vs. rigid wall (empty markers)

scholarly journals On Dam-Break Flow Routing in Confluent Channels

2019 ◽  
Vol 16 (22) ◽  
pp. 4384
Author(s):  
Sihan Chen ◽  
Yingjin Li ◽  
Zhong Tian ◽  
Qiang Fan
Keyword(s):  
Flow Field ◽  
Arrival Time ◽  
Processing Technique ◽  
Surface Flow ◽  
Dam Break ◽  
Image Processing Technique ◽  
Physical Experiments ◽  
Dam Break Flow ◽  
The Impact ◽  
Motion Images

The flood propagation at a confluence of channels exhibits a unique routing pattern, while there are few studies on the routing of dam-break flow in confluent channels. In this study, we conducted physical experiments and a numerical simulation to investigate the influence of different confluence angles on the routing of a dam-break flood. Experiments were carried out in smooth, transparent, rectangular prismatic channels to study the dam-break flow under four different confluence angles. The flow velocity was measured using an image processing technique, and the surface flow field was effectively captured by synchronously recording the particle motion images. Based on the variation of the water level and flow discharge, as the confluence angle increased, the retardation and abatement effects on the flood increased. Specifically, the flood arrival time was delayed by approximately 0.91% to 21.18%, and the peak flood discharge was reduced by approximately 9.05% to 58.36%. Combined with the surface flow field at the confluence and in the downstream sections, as the confluence angle increased, the impact points at the confluence and in the downstream straight sections moved upward, and the impact range was reduced. Combined with the pressure variation pattern, the routing of dam-break flow in the confluent channels experienced a process of impact-reflection-return-attenuation.

scholarly journals OpenFOAM Based Approach for the Prediction of the Dam Break with an Obstacle

2020 ◽  
Author(s):  
Richmond Sam Quarm
Keyword(s):  
Numerical Solution ◽  
Vertical Wall ◽  
Leading Edge ◽  
Numerical Approach ◽  
Dam Break ◽  
Free Surface Elevation ◽  
Before And After ◽  
The Difference ◽  
The Impact ◽  
Simulation Time

The phenomenon of the flow impact on a vertical wall resulting from a dam problem is simulated by using OpenFOAM. In this simulation, a dam break was also simulated with the addition of obstacles with various dimensions. The aim of this study is to assess the accuracy of the solver for problems in the impact wave category from the experimental results of previous researchers and other numerical solution techniques compared with the results of this solver. Different aspects of flow such as free surface elevation before and after the initial impact have been observed in depth. The method used in this research is numerical computation simulation with the OpenFOAM approach which has the advantage of being more accurate and fast simulation time. The variations in the dimensions of the obstacle in this study were b / h = 0.25, b / h = 0.5 and b / h = 1.0. From the simulation data, it is found that the numerical approach has been validated through quantitative comparisons with experimental measurements. The computational positions of the leading edge of the collapsed water column match the experimental data. The difference between the experiment and this numerical solution is below 2%.

scholarly journals OpenFOAM Based Approach for the Prediction of the Dam Break with an Obstacle

2020 ◽  
Author(s):  
Mohamed Osman Elamin Busharads
Keyword(s):  
Numerical Solution ◽  
Vertical Wall ◽  
Leading Edge ◽  
Numerical Approach ◽  
Dam Break ◽  
Free Surface Elevation ◽  
Before And After ◽  
The Difference ◽  
The Impact ◽  
Simulation Time

The phenomenon of the flow impact on a vertical wall resulting from a dam problem is simulated by using OpenFOAM. In this simulation, a dam break was also simulated with the addition of obstacles with various dimensions. The aim of this study is to assess the accuracy of the solver for problems in the impact wave category from the experimental results of previous researchers and other numerical solution techniques compared with the results of this solver. Different aspects of flow such as free surface elevation before and after the initial impact have been observed in depth. The method used in this research is numerical computation simulation with the OpenFOAM approach which has the advantage of being more accurate and fast simulation time. The variations in the dimensions of the obstacle in this study were b / h = 0.25, b / h = 0.5 and b / h = 1.0. From the simulation data, it is found that the numerical approach has been validated through quantitative comparisons with experimental measurements. The computational positions of the leading edge of the collapsed water column match the experimental data. The difference between the experiment and this numerical solution is below 2%.

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

Natural Convection in a Rectangular Porous Cavity With Constant Heat Flux on One Vertical Wall

1984 ◽  
Vol 106 (1) ◽  
pp. 152-157 ◽  
Author(s):  
V. Prasad ◽  
F. A. Kulacki
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Numerical Solutions ◽  
Vertical Wall ◽  
Local Heat ◽  
Constant Heat Flux ◽  
Heated Wall ◽  
Width Ratio ◽  
Constant Heat ◽  
Nusselt Numbers

Numerical solutions for two-dimensional, steady, free convection are presented for a rectangular cavity with constant heat flux on one vertical wall, the other vertical wall being isothermally cooled. The horizontal walls are insulated. Results are presented in terms of streamlines and isotherms, local and average Nusselt numbers at the heated wall, and the local heat flux at the cooled wall. Flow patterns are observed to be quite different from those in the case of a cavity with both vertical walls at constant temperatures. Specifically, symmetry in the flow field is absent and any increase in applied heat flux is not accompanied by linearly proportional increase in the temperature on the heated wall. Also, for low Prandtl number, the heat transfer rate based upon the mean temperature difference is higher as compared to experimental results for the isothermal case. Heat transfer results, further, indicate that the average Nusselt number is correlated by a relation of the form Nu = constant Ra*mAn, where Ra* is the Rayleigh number and A the height-to-width ratio of the cavity.

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.

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