Development of a New Transitional Flow Model Integrating the one-equation Wray-Agarwal Turbulence Model with an Algebraic Intermittency Transport Term

In the last decade, discontinuous Galerkin (DG) methods have been the subject of extensive research efforts because of their excellent performance in the high-order accurate discretization of advection-diffusion problems on general unstructured grids, and are nowadays finding use in several different applications. In this paper, the potential offered by a high-order accurate DG space discretization method with implicit time integration for the solution of the Reynolds-averaged Navier–Stokes equations coupled with the k-ω turbulence model is investigated in the numerical simulation of the turbulent flow through the well-known T106A turbine cascade. The numerical results demonstrate that, by exploiting high order accurate DG schemes, it is possible to compute accurate simulations of this flow on very coarse grids, with both the high-Reynolds and low-Reynolds number versions of the k-ω turbulence model.

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Volcanic synchronization of Dome Fuji and Dome C Antarctic deep ice cores over the past 216 kyr

Climate of the Past ◽

10.5194/cp-11-1395-2015 ◽

2015 ◽

Vol 11 (10) ◽

pp. 1395-1416 ◽

Cited By ~ 13

Author(s):

S. Fujita ◽

F. Parrenin ◽

M. Severi ◽

H. Motoyama ◽

E. W. Wolff

Keyword(s):

Age Differences ◽

Flow Model ◽

Ice Cores ◽

Ice Flow ◽

Surface Mass ◽

The Past ◽

The One ◽

Mis 5E ◽

Age Constraints ◽

Mis 5

Abstract. Two deep ice cores, Dome Fuji (DF) and EPICA Dome C (EDC), drilled at remote dome summits in Antarctica, were volcanically synchronized to improve our understanding of their chronologies. Within the past 216 kyr, 1401 volcanic tie points have been identified. DFO2006 is the chronology for the DF core that strictly follows O2 / N2 age constraints with interpolation using an ice flow model. AICC2012 is the chronology for five cores, including the EDC core, and is characterized by glaciological approaches combining ice flow modelling with various age markers. A precise comparison between the two chronologies was performed. The age differences between them are within 2 kyr, except at Marine Isotope Stage (MIS) 5. DFO2006 gives ages older than AICC2012, with peak values of 4.5 and 3.1 kyr at MIS 5d and MIS 5b, respectively. Accordingly, the ratios of duration (AICC2012 / DFO2006) range between 1.4 at MIS 5e and 0.7 at MIS 5a. When making a comparison with accurately dated speleothem records, the age of DFO2006 agrees well at MIS 5d, while the age of AICC2012 agrees well at MIS 5b, supporting their accuracy at these stages. In addition, we found that glaciological approaches tend to give chronologies with younger ages and with longer durations than age markers suggest at MIS 5d–6. Therefore, we hypothesize that the causes of the DFO2006–AICC2012 age differences at MIS 5 are (i) overestimation in surface mass balance at around MIS 5d–6 in the glaciological approach and (ii) an error in one of the O2 / N2 age constraints by ~ 3 kyr at MIS 5b. Overall, we improved our knowledge of the timing and duration of climatic stages at MIS 5. This new understanding will be incorporated into the production of the next common age scale. Additionally, we found that the deuterium signals of ice, δDice, at DF tends to lead the one at EDC, with the DF lead being more pronounced during cold periods. The lead of DF is by +710 years (maximum) at MIS 5d, −230 years (minimum) at MIS 7a and +60 to +126 years on average.

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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 ◽

10.17159/wsa/2019.v45.i3.6739 ◽

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.

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Modeling of Wall Friction for Multispecies Solid-Gas Flows

Journal of Fluids Engineering ◽

10.1115/1.3242608 ◽

1986 ◽

Vol 108 (4) ◽

pp. 486-488 ◽

Cited By ~ 1

Author(s):

E. D. Doss ◽

M. G. Srinivasan

Keyword(s):

Shear Stress ◽

Flow Model ◽

Flow Characteristics ◽

Wall Friction ◽

Gas Flows ◽

Two Phase ◽

One Dimensional ◽

Friction Models ◽

Wall Interaction ◽

The One

The empirical expressions for the equivalent friction factor to simulate the effect of particle-wall interaction with a single solid species have been extended to model the wall shear stress for multispecies solid-gas flows. Expressions representing the equivalent shear stress for solid-gas flows obtained from these wall friction models are included in the one-dimensional two-phase flow model and it can be used to study the effect of particle-wall interaction on the flow characteristics.

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A Dynamical and Chemical Study of NGC 6302

Symposium - International Astronomical Union ◽

10.1017/s0074180900094080 ◽

1983 ◽

Vol 103 ◽

pp. 509-509

Author(s):

I.J. Danziger ◽

D. Baade ◽

P. D. Atherton ◽

K. Taylor ◽

A. Boksenberg

Keyword(s):

Radial Velocity ◽

Large Scale ◽

Flow Model ◽

Chemical Study ◽

Large Scale Structure ◽

Scale Structure ◽

Two Dimensional ◽

Cavity Model ◽

Ionic Concentrations ◽

The One

From five spectrograms obtained at five different positions in the nebula, relative ionic concentrations have been derived with respect to the nucleus. They show that the degree of excitation generally decreases with distance from the nucleus. But there are also areas with locally enhanced or attenuated excitation. Taurus data, a series of two-dimensional monochromatic images centered on (OIII) λ 5007, have been used to construct a two-dimensional velocity map. It shows a large-scale structure similar to the one of direct images with the biconical pattern being at least partly present. Areas of locally lower radial velocity which seem to be inversion symmetrically distributed with respect to the centre, are also distinguished. They do not have pronounced counterparts on direct images. The cavity model suggested by Barral et al. (1982, MNRAS 199, 95) for NGC 6302 and Icke's biconical flow model (1981, Ap. J. 247, 152) are discussed.

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Impact of Energy Slope Averaging Methods on Numerical Solution of 1D Steady Gradually Varied Flow

Archives of Hydro-Engineering and Environmental Mechanics ◽

10.1515/heem-2015-0022 ◽

2015 ◽

Vol 62 (3-4) ◽

pp. 101-119 ◽

Cited By ~ 1

Author(s):

Wojciech Artichowicz ◽

Dzmitry Prybytak

Keyword(s):

Numerical Methods ◽

Numerical Solution ◽

Numerical Integration ◽

Cross Sections ◽

Flow Model ◽

One Dimensional ◽

Averaging Methods ◽

Integration Formulas ◽

Different Types ◽

The One

AbstractIn this paper, energy slope averaging in the one-dimensional steady gradually varied flow model is considered. For this purpose, different methods of averaging the energy slope between cross-sections are used. The most popular are arithmetic, geometric, harmonic and hydraulic means. However, from the formal viewpoint, the application of different averaging formulas results in different numerical integration formulas. This study examines the basic properties of numerical methods resulting from different types of averaging.

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Sensitization of the SST Turbulence Model to Rotation and Curvature by Applying the Spalart–Shur Correction Term

Journal of Turbomachinery ◽

10.1115/1.3070573 ◽

2009 ◽

Vol 131 (4) ◽

Cited By ~ 139

Author(s):

Pavel E. Smirnov ◽

Florian R. Menter

Keyword(s):

Turbulent Flows ◽

Turbulence Model ◽

Transport Model ◽

Correction Term ◽

Computational Cost ◽

Turbulence Models ◽

Reynolds Stress Transport Model ◽

Wide Range ◽

Sst Model ◽

The One

A rotation-curvature correction suggested earlier by Spalart and Shur (1997, “On the Sensitization of Turbulence Models to Rotation and Curvature,” Aerosp. Sci. Technol., 1(5), pp. 297–302) for the one-equation Spalart–Allmaras turbulence model is adapted to the shear stress transport model. This new version of the model (SST-CC) has been extensively tested on a wide range of both wall-bounded and free shear turbulent flows with system rotation and/or streamline curvature. Predictions of the SST-CC model are compared with available experimental and direct numerical simulations (DNS) data, on the one hand, and with the corresponding results of the original SST model and advanced Reynolds stress transport model (RSM), on the other hand. It is found that in terms of accuracy the proposed model significantly improves the original SST model and is quite competitive with the RSM, whereas its computational cost is significantly less than that of the RSM.

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Development and Initial Validation of a Two-Equation Transition Sensitive Turbulence Model for CFD Simulations

Fluids Engineering ◽

10.1115/imece2006-14956 ◽

2006 ◽

Author(s):

J. M. Jones ◽

D. K. Walters

Keyword(s):

Boundary Layer ◽

Turbulence Model ◽

Eddy Viscosity ◽

Flow Behavior ◽

Boundary Layer Separation ◽

Transitional Flow ◽

Model Framework ◽

Modeling Framework ◽

Initial Development ◽

New Model

This paper presents the initial development and validation of a modified two-equation eddy-viscosity turbulence model for computational fluid dynamics (CFD) prediction of transitional and turbulent flow. The new model is based on a k-ω model framework, making it more easily implemented into existing general-purpose CFD solvers than other recently proposed model forms. The model incorporates inviscid and viscous damping functions for the eddy viscosity, as well as a production damping term, in order to reproduce the appropriate effects of laminar, transitional, and turbulent boundary layer flow. It has been implemented into a commercially available flow solver (FLUENT) and evaluated for simple attached and separated flow conditions, including 2-D flow over a flat plate and a circular cylinder. The results presented show that the new model is able to yield reasonable predictions of transitional flow behavior using a very simple modeling framework, including an appropriate response to freestream turbulence and boundary layer separation.

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Verification of a One-Dimensional Two-Phase Flow Model of the Frontal Gap in Electrochemical Machining

Journal of Engineering for Industry ◽

10.1115/1.3438894 ◽

1976 ◽

Vol 98 (2) ◽

pp. 431-437 ◽

Cited By ~ 4

Author(s):

F. Fluerenbrock ◽

R. D. Zerkle ◽

J. F. Thorpe

Keyword(s):

Flow Model ◽

Radial Flow ◽

Electrochemical Machining ◽

Equilibrium Conditions ◽

Two Phase ◽

One Dimensional ◽

Supply Pressure ◽

Theoretical Predictions ◽

The One ◽

Experimental Pressure

A set of six equations, which are based on the ECM model developed by Thorpe and Zerkle, can be solved numerically to yield the one-dimensional distributions of pressure, temperature, gas density, gap thickness, void fraction, and electrolyte velocity in the rectilinear ECM frontal gap under equilibrium conditions. The validity of the model, which also applies to radial flow geometries, is confirmed by comparing experimental pressure and gap profiles with theoretical predictions. It is shown that for a given set of operating parameters there is a minimum supply pressure below which no machining is possible. When machining steel with an aqueous NaCl electrolyte the deposition of a black smut (Fe(OH)2) occurs beyond a certain smut-free entrance length, which was experimentally found to be proportional to the inlet gap thickness.

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