scholarly journals On the Effect of Block Roughness in Ogee Spillways with Flip Buckets

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 182
Author(s):  
Rasoul Daneshfaraz ◽  
Amir Ghaderi ◽  
Aliakbar Akhtari ◽  
Silvia Di Francesco
Keyword(s):  
Energy Dissipation ◽  
Numerical Model ◽  
Turbulence Model ◽  
Volume Of Fluid ◽  
Relative Energy ◽  
Vof Method ◽  
Free Flow ◽  
Jet Length ◽  
Numerical Tests ◽  
Flow Surface

In this study, the effect of the presence of bed-block roughness in an ogee spillway on energy dissipation and jet length is investigated. A series of experimental and numerical tests were conducted using an ogee spillway with block roughness on the bed without a flip bucket and with a flip bucket at different take-off angles (32 °C and 52 °C). To model the free-flow surface, the volume-of-fluid (VOF) method and turbulence model from RNG k–ε were used. Results indicated that the numerical model is fairly capable of simulating a free-flow surface over an ogee spillway; using block roughness on the spillway chute without a bucket, relative energy dissipation increased by 15.4% compared to that in the spillway with a smooth bed, while for the spillway with 32 °C and 52 °C buckets, it increased by 9.5%. The jet length for a spillway with a flip bucket and roughened bed decreased by 8% to 58% compared to that in a smooth bed. Lastly, the relationships for the estimation of relative energy dissipation and jet length are presented.

scholarly journals Study of Energy Dissipation of Pooled Stepped Spillways

2016 ◽  
Vol 2 (5) ◽  
pp. 208-220 ◽  
Author(s):  
Khosro Morovati ◽  
Afshin Eghbalzadeh ◽  
Saba Soori
Keyword(s):  
Experimental Data ◽  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Relative Energy ◽  
Turbulence Simulation ◽  
Stepped Spillways ◽  
Flow Surface ◽  
Flow Turbulence ◽  
Rng Turbulence Model

Water transferring to the dam downstream creates high levels of kinetic energy. Stepped spillways are amongst the most effective spillways in reducing the kinetic energy of the flow moving towards the downstream. The geometry of the steps in stepped spillways can affect the reduction of kinetic energy of the flow transferring to the downstream. Therefore, in this study the effect of different number of steps and discharge on flow pattern especially energy dissipation were investigated. The VOF method was used to simulate the flow surface and the k-ε (RNG) turbulence model was used for flow turbulence simulation. Comparing the results obtained from the numerical simulation with the experimental data indicated an acceptable level of consistency. Comparing the obtained results showed that decreasing the number of the steps of pooled stepped spillways reduced flow velocity and increased the relative energy dissipation at the end of the spillway. Decreasing the number of steps increased the turbulent kinetic energy value. Also, the maximum turbulent kinetic energy was obtained near the step’s pool. Moreover the results indicated that the value of turbulent kinetic energy increased along the spillway. 

Numerical Simulation of Droplet Ejection Based on VOF Method

2014 ◽  
Vol 548-549 ◽  
pp. 1257-1264 ◽  
Author(s):  
Xiao Yong Suo
Keyword(s):  
Numerical Simulation ◽  
Surface Tension ◽  
Numerical Model ◽  
Physical Properties ◽  
Vof Method ◽  
Numerical Results ◽  
Droplet Ejection ◽  
Ejection Process ◽  
Ink Jet ◽  
Jet Nozzle

Taking ejection process of the ink droplets from ink-jet nozzle as the prototype, a similar numerical model of droplet ejection was established. The VOF method was applied to track the interface of droplet ejection process and it is shown that the numerical results simulated by the VOF method were accurate and reliable. Six kinds of liquid with different physical properties were chosen as the research object. The numerical results were analyzed and compared. Finally, the effect of the surface tension, viscosity and density on the droplet ejection process was discussed.

Advanced understanding of local wetting behaviour in gas-liquid-solid packed beds using CFD with a volume of fluid (VOF) method

2017 ◽  
Vol 170 ◽  
pp. 378-392 ◽  
Author(s):  
Wei Du ◽  
Jianzhou Zhang ◽  
Panpan Lu ◽  
Jian Xu ◽  
Weisheng Wei ◽  
...  
Keyword(s):  
Volume Of Fluid ◽  
Vof Method ◽  
Packed Beds

scholarly journals On the validation of the LS-DYNA Geo Metro numerical model

2019 ◽  
Vol 262 ◽  
pp. 10001 ◽  
Author(s):  
Dawid Bruski ◽  
Stanisław Burzyński ◽  
Jacek Chróścielewski ◽  
Łukasz Pachocki ◽  
Wojciech Witkowski
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Road Safety ◽  
Finite Element Code ◽  
Numerical Tests ◽  
Safety Barriers ◽  
The Subject ◽  
Crash Tests

The paper presents experiences gained during work with numerical model of Geo Metro vehicle used for simulations of crash tests with road safety barriers. Attention is drawn to the subject of tire/wheel breakage during collision events. Some methods for improvement of the model are presented in the paper. Several results for the normative vehicle numerical tests are introduced. Simulations were carried out using LS-DYNA finite element code with solver version R8.1.

scholarly journals 3-D numerical modelling of crustal polydiapirs with volume-of-fluid methods

2020 ◽  
Vol 222 (1) ◽  
pp. 474-506
Author(s):  
Aurélie Louis-Napoléon ◽  
Muriel Gerbault ◽  
Thomas Bonometti ◽  
Cédric Thieulot ◽  
Roland Martin ◽  
...  
Keyword(s):  
Volume Of Fluid ◽  
Vof Method ◽  
Earth’S Crust ◽  
Gravitational Instabilities ◽  
Interface Reconstruction ◽  
Rayleigh Taylor Instability ◽  
Earth's Crust ◽  
Two Stages ◽  
Rayleigh Benard ◽  
Earth Dynamics

SUMMARY Gravitational instabilities exert a crucial role on the Earth dynamics and in particular on its differentiation. The Earth’s crust can be considered as a multilayered fluid with different densities and viscosities, which may become unstable in particular with variations in temperature. With the specific aim to quantify crustal scale polydiapiric instabilities, we test here two codes, JADIM and OpenFOAM, which use a volume-of-fluid (VOF) method without interface reconstruction, and compare them with the geodynamics community code ASPECT, which uses a tracking algorithm based on compositional fields. The VOF method is well-known to preserve strongly deforming interfaces. Both JADIM and OpenFOAM are first tested against documented two and three-layer Rayleigh–Taylor instability configurations in 2-D and 3-D. 2-D and 3-D results show diapiric growth rates that fit the analytical theory and are found to be slightly more accurate than those obtained with ASPECT. We subsequently compare the results from VOF simulations with previously published Rayleigh–Bénard analogue and numerical experiments. We show that the VOF method is a robust method adapted to the study of diapirism and convection in the Earth’s crust, although it is not computationally as fast as ASPECT. OpenFOAM is found to run faster than, and conserve mass as well as JADIM. Finally, we provide a preliminary application to the polydiapiric dynamics of the orogenic crust of Naxos Island (Greece) at about 16 Myr, and propose a two-stages scenario of convection and diapirism. The timing and dimensions of the modelled gravitational instabilities not only corroborate previous estimates of timing and dimensions associated to the dynamics of this hot crustal domain, but also bring preliminary insight on its rheological and tectonic contexts.

scholarly journals A Modified k – ε Turbulence Model for a Wave Breaking Simulation

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2282
Author(s):  
Giovanni Cannata ◽  
Federica Palleschi ◽  
Benedetta Iele ◽  
Francesco Gallerano
Keyword(s):  
Energy Dissipation ◽  
Turbulence Model ◽  
Wave Breaking ◽  
A Priori ◽  
Time Dependent ◽  
Breaking Wave ◽  
Vertical Coordinate ◽  
Initial Wave ◽  
Proposed Model ◽  
Curvilinear Coordinate

We propose a two-equation turbulence model based on modification of the k − ε standard model, for simulation of a breaking wave. The proposed model is able to adequately simulate the energy dissipation due to the wave breaking and does not require any “a priori” criterion to locate the initial wave breaking point and the region in which the turbulence model has to be activated. In order to numerically simulate the wave propagation from deep water to the shoreline and the wave breaking, we use a model in which vector and tensor quantities are expressed in terms of Cartesian components, where only the vertical coordinate is expressed as a function of a time-dependent curvilinear coordinate that follows the free surface movements. A laboratory test is numerically reproduced with the aim of validating the turbulence modified k − ε model. The numerical results compared with the experimental measurements show that the proposed turbulence model is capable of correctly estimating the energy dissipation induced by the wave breaking, in order to avoid any underestimation of the wave height.

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