An evaluation of the one-dimensional turbulence model: Comparison with direct numerical simulations of CO/H2 jets with extinction and reignition

2011 ◽  
Vol 33 (1) ◽  
pp. 1515-1522 ◽  
Author(s):  
Naveen Punati ◽  
James C. Sutherland ◽  
Alan R. Kerstein ◽  
Evatt R. Hawkes ◽  
Jacqueline H. Chen
Keyword(s):  
Numerical Simulations ◽  
Turbulence Model ◽  
Model Comparison ◽  
Direct Numerical Simulations ◽  
One Dimensional ◽  
The One

scholarly journals Assessment of CFD turbulence models for free surface flow simulation and 1-D modelling for water level calculations over a broad-crested weir floodway

Water SA ◽  
2019 ◽  
Vol 45 (3 July) ◽  
Author(s):  
Ahmed M Helmi
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Water Level ◽  
Dimensional Analysis ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Cfd Simulations ◽  
One Dimensional ◽  
The Mean ◽  
The One

Floodways, where a road embankment is permitted to be overtopped by flood water, are usually designed as broad-crested weirs. Determination of the water level above the floodway is crucial and related to road safety. Hydraulic performance of floodways can be assessed numerically using 1-D modelling or 3-D simulation using computational fluid dynamics (CFD) packages. Turbulence modelling is one of the key elements in CFD simulations. A wide variety of turbulence models are utilized in CFD packages; in order to identify the most relevant turbulence model for the case in question, 96 3-D CFD simulations were conducted using Flow-3D package, for 24 broad-crested weir configurations selected based on experimental data from a previous study. Four turbulence models (one-equation, k-ε, RNG k-ε, and k-ω) ere examined for each configuration. The volume of fluid (VOF) algorithm was adopted for free water surface determination. In addition, 24 1-D simulations using HEC-RAS-1-D were conducted for comparison with CFD results and experimental data. Validation of the simulated water free surface profiles versus the experimental measurements was carried out by the evaluation of the mean absolute error, the mean relative error percentage, and the root mean square error. It was concluded that the minimum error in simulating the full upstream to downstream free surface profile is achieved by using one-equation turbulence model with mixing length equal to 7% of the smallest domain dimension. Nevertheless, for the broad-crested weir upstream section, no significant difference in accuracy was found between all turbulence models and the one-dimensional analysis results, due to the low turbulence intensity at this part. For engineering design purposes, in which the water level is the main concern at the location of the flood way, the one-dimensional analysis has sufficient accuracy to determine the water level.

DROPLET FEEDBACK ON VAPOR IN A WARM CLOUD

2009 ◽  
Vol 23 (28n29) ◽  
pp. 5434-5443 ◽  
Author(s):  
ANTONIO CELANI ◽  
ANDREA MAZZINO ◽  
MARCO TIZZI
Keyword(s):  
Numerical Simulations ◽  
Droplet Size ◽  
Cloud Droplet ◽  
Direct Numerical Simulations ◽  
Cloud Droplets ◽  
Size Spectra ◽  
New Model ◽  
Warm Cloud ◽  
Local Reduction ◽  
The One

A new model to study the effect of turbulence on the cloud droplets in the condensation phase is proposed and its behavior investigated by direct numerical simulations. The model is a generalization of the one by Celani, Mazzino, Tizzi, New J. Phys.10, 075021 (2008), where the droplet feedback on vapor is now explicitly taken into account. Physically, it amounts to considering the fact that when a cloud droplet increases its size, vapor is subtracted from the ambient with the net result of a local reduction in the supersaturation field. It is shown how this effect plays to reduce the broadening of droplet size spectra in the condensation stage and thus to produce results in closer agreement with observations.

scholarly journals Particle dispersion in homogeneous turbulence using the one-dimensional turbulence model

2014 ◽  
Vol 26 (10) ◽  
pp. 103301 ◽  
Author(s):  
Guangyuan Sun ◽  
David O. Lignell ◽  
John C. Hewson ◽  
Craig R. Gin
Keyword(s):  
Turbulence Model ◽  
Particle Dispersion ◽  
Homogeneous Turbulence ◽  
One Dimensional ◽  
The One

Structures of reconnection layers based on the ideal magnetohydrodynamic equations

1994 ◽  
Vol 51 (3) ◽  
pp. 381-398
Author(s):  
Wenlong Dai ◽  
Paul R. Woodward
Keyword(s):  
Numerical Simulations ◽  
Quantitative Agreement ◽  
Mhd Equations ◽  
Riemann Solver ◽  
Magnetohydrodynamic Equations ◽  
One Dimensional ◽  
Ideal Mhd ◽  
Ideal Magnetohydrodynamic ◽  
The One ◽  
The Ideal

A Riemann solver is used, and a set of numerical simulations are performed, to study the structures of reconnection layers in the approximation of the one- dimensional ideal MHD equations. Since the Riemann solver may solve general Riemarin problems, the model used in this paper is more general than those in previous investigations on this problem. Under the conditions used in the previous investigations, the structures we obtained are the same. Our numerical simulations show quantitative agreement with those obtained through the Riemann solver.

scholarly journals INVESTIGATION OF STATIONARY SOLUTIONS OF VISCOELASTIC MELT SPINNING EQUATIONS AND STABILITY WITH RESPECT TO INCREASING VISCOELASTICITY

2010 ◽  
Vol 15 (3) ◽  
pp. 287-298 ◽  
Author(s):  
R. Dhadwal ◽  
S. K. Kudtarkar
Keyword(s):  
Constitutive Equation ◽  
Numerical Simulations ◽  
Existence And Uniqueness ◽  
Melt Spinning ◽  
Stationary Solutions ◽  
Model Parameter ◽  
One Dimensional ◽  
Spinning Process ◽  
The Stability ◽  
The One

The one‐dimensional equations governing the formation of viscoelastic fibers using Giesekus constitutive equation were studied. Existence and uniqueness of stationary solutions was shown and relation between the stress at the spinneret and the take‐up velocity was found. Further, the value of the Giesekus model parameter for which the fibre exhibits Newtonian behaviour was found analytically. Using numerical simulations it was shown that below this value of the parameter the fluid shows extension thickening behaviour and above, extension thinning. In this context, by simulating the non‐stationary equations the effect of viscoelasticity on the stability of the spinning process was studied.

The one-dimensional minesweeper game: What are your chances of winning?

2016 ◽  
Vol 27 (11) ◽  
pp. 1650127 ◽  
Author(s):  
M. Rodríguez-Achach ◽  
H. F. Coronel-Brizio ◽  
A. R. Hernández-Montoya ◽  
R. Huerta-Quintanilla ◽  
E. Canto-Lugo
Keyword(s):  
Numerical Simulations ◽  
Critical Density ◽  
Computer Game ◽  
Simple System ◽  
Two Dimensional ◽  
Dimensional Lattice ◽  
One Dimensional ◽  
Np Completeness ◽  
The One ◽  
Good Agreement

Minesweeper is a famous computer game consisting usually in a two-dimensional lattice, where cells can be empty or mined and gamers are required to locate the mines without dying. Even if minesweeper seems to be a very simple system, it has some complex and interesting properties as NP-completeness. In this paper and for the one-dimensional case, given a lattice of n cells and m mines, we calculate the winning probability. By numerical simulations this probability is also estimated. We also find out by mean of these simulations that there exists a critical density of mines that minimize the probability of winning the game. Analytical results and simulations are compared showing a very good agreement.

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