scholarly journals Experimental and Numerical Analysis of 3D Dam-Break Waves in an Enclosed Domain with a Single Oriented Obstacle

2020 ◽  
Vol 2 (1) ◽  
pp. 35
Author(s):  
Selahattin Kocaman ◽  
Stefania Evangelista ◽  
Giacomo Viccione ◽  
Hasan Güzel
Keyword(s):  
Three Dimensional ◽  
Dam Break ◽  
Small Scale ◽  
Complex Flow ◽  
Free Surfaces ◽  
Dam Break Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Dam Breaking ◽  
3D Software ◽  
Downstream Area

Flood caused by a dam-breaking flow may be catastrophic for the downstream area due to the sudden discharge of large volumes of water. Besides the complex flow of the propagating dam-break wave, the presence of structures such as bridges and buildings yield free surfaces which can be accurately reproduced by means of three-dimensional Computational Fluid Dynamics (CFD) software. The prediction of the dam-break flow main features in the presence of obstacles has a crucial role in decreasing the damage. In this study, small-scale laboratory experiments were conducted to examine the problem with a single obstacle. Five ultrasonic sensors were used as measurement devices. Measurements were compared with the numerical results obtained with the FLOW-3D software, solving RANS equations with the k- turbulence closure model. A good agreement was observed.

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 Cold Flow Computations for the Diffuser-Combustor Section of an Industrial Gas Turbine

1996 ◽  
Author(s):  
Dadong Zhou ◽  
Ting Wang ◽  
William R. Ryan
Keyword(s):  
Gas Turbine ◽  
Total Pressure ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Complex Flow ◽  
Pressure Losses ◽  
Structured Grid ◽  
Computational Fluid Dynamics Cfd ◽  
Enhance Efficiency ◽  
Industrial Gas Turbine

In the first part of a multipart project to analyze and optimize the complex three-dimensional diffuser-combustor section of a highly advanced industrial gas turbine under development, a computational fluid dynamics (CFD) analysts has been conducted. The commercial FEA code I-DEAS was used to complete the three-dimensional solid modeling and the structured grid generation. The flow calculation was conducted using the commercial CFD code PHOENICS. The multiblock method was employed to enhance computational capabilities. The mechanisms of the total pressure losses and possible ways to enhance efficiency by reducing the total pressure losses were examined. Mechanisms that contribute to the nonuniform velocity distribution of flow entering the combustor were also identified. The CFD results were informative and provided insight to the complex flow patterns in the reverse flow dump diffuser, however, the results are qualitative and are useful primarily as guidelines for optimization as opposed to firm design configuration selections.

GPU Based Acceleration of MPS Method for Three-Dimensional Dam-Break Flows

2018 ◽  
Author(s):  
Xiang Chen ◽  
Decheng Wan
Keyword(s):  
Numerical Methods ◽  
Computational Efficiency ◽  
Three Dimensional ◽  
Computation Time ◽  
Dam Break ◽  
Gpu Acceleration ◽  
Mps Method ◽  
Acceleration Technique ◽  
Dam Break Flow ◽  
Moving Particle

The Moving Particle Semi-implicit (MPS) method has been proven effective to simulate violent flows such as dam-break flow, liquid sloshing and so on. But the low computational efficiency is one disadvantage of MPS. In the field of scientific computations, GPU based acceleration technique is widely applied to reduce the computation time of various numerical methods. In this paper, an in-house solver MPSGPU-SJTU is developed based on modified MPS method and GPU acceleration technique. A three-dimensional (3-D) dam-break flow is simulated by present solver and the validity and accuracy of GPU code are investigated by comparing the results with those by other researches. By comparisons, the flow field of GPU-based calculation is in better agreement with the experiment. In addition, the computation times of GPU and CPU solvers are compared to demonstrate the effect of GPU acceleration technique on the computational efficiency of MPS method.

Computational Fluid Dynamics (CFD) Analysis of a Single-Stage Downhole Turbine

2013 ◽  
Author(s):  
Rajani Satti ◽  
Narasimha Rao Pillalamarri ◽  
Eckard Scholz
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Operating Regime ◽  
Single Stage ◽  
Tip Clearance ◽  
Performance Characteristics ◽  
Design Parameters ◽  
Complex Flow ◽  
Computational Fluid Dynamics Cfd

In this study, the application of computational fluid dynamics (CFD) is explored to predict the performance characteristics in a typical single-stage downhole turbine. The single-stage turbine model utilized for this study consists of a stator and a rotor. A finite-volume based CFD approach was implemented to simulate the complex flow field around the turbine. The analysis is based on transient, three-dimensional, isothermal turbulent flow in an incompressible fluid system. The inlet flow rates and angular velocity of the rotor were varied to encompass the operating regime. Comparison with experimental data revealed excellent agreement, proving reliability of the model in predicting the performance characteristics. Motivated by the successful model validation, a parametric study (considering blade tip clearance and blade count) was also conducted to understand the effects of the design parameters on the performance of the turbine. Detailed flow visualizations and efficiency calculations were also done to provide further insight into the overall performance of the turbine. As part of the present study, significant efforts were also spent in the following areas: standardization of CFD methodology and assessment of commercial software to develop an integrated CFD-driven design process.

The initial stages of dam-break flow

1998 ◽  
Vol 374 ◽  
pp. 407-424 ◽  
Author(s):  
P. K. STANSBY ◽  
A. CHEGINI ◽  
T. C. D. BARNES
Keyword(s):  
Dam Break ◽  
Complex Flow ◽  
Jet Formation ◽  
Initial Release ◽  
Flow Interactions ◽  
Nonlinear Potential ◽  
Small Times ◽  
Dam Break Flow ◽  
Surface Profiles ◽  
Different Levels

Experiments have been undertaken to investigate dam-break flows where a thin plate separating water at different levels is withdrawn impulsively in a vertically upwards direction. Depth ratios of 0, 0.1 and 0.45 were investigated for two larger depth values of 10 cm and 36 cm. The resulting sequence of surface profiles is shown to satisfy approximately Froude scaling. For the dry-bed case a horizontal jet forms at small times and for the other cases a vertical, mushroom-like jet occurs, none of which have been observed previously. We analyse the initial-release problem in which the plate is instantaneously removed or dissolved. Although this shows singular behaviour, jet-like formations are predicted. Artificially smoothing out the singularity enables a fully nonlinear, potential-flow computation to follow the jet formation for small times. There is qualitative agreement between theory and experiment.In the experiments, after a bore has developed downstream as a result of highly complex flow interactions, the surface profiles agree remarkably well with exact solutions of the shallow-water equations which assume hydrostatic pressure and uniform velocity over depth.

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 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.

Numerical Simulation on Small Scale Straight-Blade and Twisted-Blade Vertical Axis Wind Turbine

2012 ◽  
Vol 455-456 ◽  
pp. 334-338
Author(s):  
Yong Zhe Lv ◽  
Dong Xiang Jiang ◽  
Yong Jiang
Keyword(s):  
Wind Turbine ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Small Scale ◽  
Vertical Axis Wind Turbine ◽  
Straight Blade ◽  
Fluid Field ◽  
Solid Models ◽  
Computational Fluid Dynamics Cfd ◽  
Twisted Blade

This paper presents an analysis on the performance of vertical axis wind turbine of two types, namely straight-blade vertical axis wind turbine (SB-VAWT) and twisted-blade vertical axis wind turbine (TB-VAWT). An attempt of this simulation is to identify which type performs better in the same wind conditions and swept area. Three-dimensional computational fluid dynamics (CFD) was adopted in this analysis, after solid models of them were generated. Preliminary results of torque, power and aerodynamics in the fluid field were obtained for discussion. Finally, there provided some guidance for future wind tunnel tests.

scholarly journals Computational Fluid Dynamics (CFD) as a Tool for Investigating Self-Organized Ascending Bubble-Driven Flow Patterns in Champagne Glasses

Foods ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 972
Author(s):  
Fabien Beaumont ◽  
Gérard Liger-Belair ◽  
Guillaume Polidori
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Bubble Column ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Complex Flow ◽  
Self Organized ◽  
Laser Tomography ◽  
Image Velocimetry ◽  
Computational Fluid Dynamics Cfd

Champagne glasses are subjected to complex ascending bubble-driven flow patterns, which are believed to enhance the release of volatile organic compounds in the headspace above the glasses. Based on the Eulerian–Lagrangian approach, computational fluid dynamics (CFD) was used in order to examine how a column of ascending bubbles nucleated at the bottom of a classical champagne glass can drive self-organized flow patterns in the champagne bulk and at the air/champagne interface. Firstly, results from two-dimensional (2D) axisymmetric simulations were compared with a set of experimental data conducted through particle image velocimetry (PIV). Secondly, a three-dimensional (3D) model was developed by using the conventional volume-of-fluid (VOF) multiphase method to resolve the interface between the mixture’s phases (wine–air). In complete accordance with several experimental observations conducted through laser tomography and PIV techniques, CFD revealed a very complex flow composed of surface eddies interacting with a toroidal flow that develops around the ascending bubble column.

Uncertainty in Dam Break Flow Simulation

1989 ◽  
Vol 20 (4-5) ◽  
pp. 249-256 ◽  
Author(s):  
Chen Shan Kung
Keyword(s):  
Unsteady Flow ◽  
Flow Model ◽  
Flow Simulation ◽  
Dam Break ◽  
Roughness Coefficient ◽  
Natural Conditions ◽  
One Dimensional ◽  
Dam Break Flow ◽  
Manning’S Coefficient ◽  
Dam Breaking

The flow caused by a dam breaking across its entire length can be approximated by a one-dimensional, unsteady flow model in form of the St. Venant equations. In this model, the flow is governed by the river geometry and the river roughness, which is quantified by Manning's coefficient. The roughness characteristics are generally difficult to estimate under natural conditions. Thus, the estimates of the Manning's coefficient will in general be subject to uncertainty. In this paper, the uncertainty in the discharge and depth hydrographs due to the uncertainty in estimating the roughness characteristics of a river, is investigated. A specific case of the Noppikoski dam in Sweden that failed in 1985 is used to illustrate the sensitivity of the flow simulation on the roughness coefficient. The analysis shows that the uncertainty in the dam break flow simulation due to the uncertainty in estimating Manning's coefficient, is significant. The uncertainty is larger at greater distances from the dam, and is greater for the discharge hydrograph than for the depth hydrograph.

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