Assessment of turbulence models for the simulation of turbulent flows past bluff bodies
TL;DR: In this paper, a one-equation turbulence model is proposed to predict 3D complex engineering flows with massive separation, and the model is shown to resolve turbulent flow structures, thereby predicting all major unsteady phenomena with a marked improvement over other Reynolds average Navier-Stokes (RANS) models.
About: This article is published in Journal of Wind Engineering and Industrial Aerodynamics.The article was published on 2016-07-01. It has received 31 citations till now. The article focuses on the topics: Reynolds stress equation model & K-epsilon turbulence model.
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01 Jan 2002
TL;DR: In this article, the authors extended the range of applications of DES towards a fully unsteady three-dimensional case with strong streamline curvature, which is known to be a major problem for Reynolds-averaged Navier-Stokes equation (RANS) methods.
Abstract: Latest developments in the simulation of turbulence by detached eddy simulation (DES) have suggested that this technique might be able to replace large eddy simulation (LES) within the next decade. The results of the flow past a square cylinder show that this approach is quite inexpensive compared to LES while capturing the most important features of the flow. This study extends the range of applications of DES towards a fully unsteady three-dimensional case with strong streamline curvature, which is known to be a major problem for Reynolds-averaged Navier-Stokes equation (RANS) methods. The case considered is the turbulent flow over wall-mounted cubes at a Reynolds number of Re = 1.3 x 10 4 . The results demonstrate that DES is able to capture the most dominant flow patterns like LES, while RANS only gives a only a poor representation of the unsteady flow phenomena
72 citations
TL;DR: In this paper, a three-dimensional micro combustor model was built to investigate impact of various turbulence models on combustion and emission behavior of studied hydrogen/air flames, and performance evaluation of these models was executed by examining combustor outer wall temperature distribution; combustor centerline temperature, velocity, pressure, species and NOx profiles.
61 citations
TL;DR: In this article, a full-scale NASCAR Gen 6 Cup car was simulated using three commonly used eddy viscosity turbulence models, viz. the realizable and AKN k − e, and SST k − ω.
36 citations
TL;DR: In this article, wind flow over dune scarps and their subsequent various slopes is studied for understanding sediment transport pathways from beach to dunes, and the authors show that wind flow can be used to predict sediment transport in dunes.
Abstract: Knowledge of wind flow over dune scarps and, as scarps fill, their subsequent various slopes, is important for understanding sediment transport pathways from beach to dunes. In this study, flow ove...
30 citations
TL;DR: In this paper, the nature of wind flow over a small, 0.6m high foredune scarp is investigated on the Sir Richard Peninsula, South Australia during a variety of incident wind directions and speeds.
Abstract: The nature of wind flow over a small, 0.6m high foredune scarp is investigated on the Sir Richard Peninsula, South Australia during a variety of incident wind directions and speeds. The study provides additional supporting evidence that the presence of the scarp and the dune exerts a strong influence on a landwards trending reduction in wind velocity and an increase in turbulence, with the greatest area of turbulence occurring near and at the foredune scarp base. For an incident oblique wind, an alongshore helicoidal flow is formed within a separation region along the scarp basal region. In this region, the coefficient of variation (CV) of wind speed is high and displays significant fluctuations. The flow at the scarp crest is compressed, streamlined and accelerated, turbulence is suppressed, and local jets may occur depending on the incident wind approach angle. Jets are more likely where the incident flow is perpendicular or nearly so. A flow separation region does not develop downwind of the scarp crest where the morphology of the foredune stoss slope downwind of the scarp is more convex (as in this case) rather than relatively flat, and possibly due to the presence of vegetation at the scarp crest. A tentative model of the flow regions developed across a backshore– scarp–foredune region during oblique incident flow is provided. © 2018 John Wiley & Sons, Ltd.
25 citations
Cites background or result from "Assessment of turbulence models for..."
...…jets as seen just seaward of the scarp crest (2D-4) and on the foredune stoss slope (2D-6) are common near, and at the crest of steep cliffs and scarps and also over high foredunes (Hsu, 1977; Hesp et al., 2009; Yasin and Al-Harbi, 2013; Pires et al., 2015; Elkhoury, 2016; Hesp and Smyth, 2016)....
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...Such jets as seen just seaward of the scarp crest (2D-4) and on the foredune stoss slope (2D-6) are common near, and at the crest of steep cliffs and scarps and also over high foredunes (Hsu, 1977; Hesp et al., 2009; Yasin and Al-Harbi, 2013; Pires et al., 2015; Elkhoury, 2016; Hesp and Smyth, 2016)....
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...If the morphology of the dune (or other topography) is flat to relatively flat downwind of the scarp crest, flow separation usually occurs and a region of turbulent reversing flow develops (Wilhelm et al., 2003; Largeau and Moriniere, 2007; Pires et al., 2015; Rowcroft et al., 2015; Elkhoury, 2016)....
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...…where the crest is around 90° to the scarp wall, and unvegetated, there is typically a region of separated reversing flow (see multiple studies reviewed in Bowen and Lindley, 1974, 1977; Hattori and Nagano, 2010; and Elkhoury, 2016), but this separation zone does not appear to occur at this site....
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...This is due to the high vertical acceleration of flow up, and then over the scarp crest as observed in Figure 7, and in many other studies (Rowcroft et al., 2014; Elkhoury, 2016)....
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References
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06 Jan 1992
8,784 citations
TL;DR: The article gives an overview of the Scale-Adaptive Simulation (SAS) method and the motivation for the formulation of the SAS method is given and a detailed explanation of the underlying ideas is presented.
Abstract: The article gives an overview of the Scale-Adaptive Simulation (SAS) method developed by the authors during the last years. The motivation for the formulation of the SAS method is given and a detailed explanation of the underlying ideas is presented. The derivation of the high-Reynolds number form of the equations as well as the calibration of the constants is provided. The concept of SAS is explained using several generic examples and test cases. In a companion article, the model is applied to more complex industrial-type applications.
724 citations
TL;DR: In this article, an ensemble-averaged statistics at constant phase of the turbulent near-wake flow (Reynolds number ≈ 21400 around a square cylinder) were obtained from two-component laser-Doppler measurements.
Abstract: Ensemble-averaged statistics at constant phase of the turbulent near-wake flow (Reynolds number ≈ 21400 around a square cylinder have been obtained from two-component laser-Doppler measurements. Phase was defined with reference to a signal taken from a pressure sensor located at the midpoint of a cylinder sidewall. The distinction is drawn between the near wake where the shed vortices are ‘mature’ and distinct and a base region where the vortices grow to maturity and are then shed. Differences in length and velocity scales and vortex celerities between the flow around a square cylinder and the more frequently studied flow around a circular cylinder are discussed. Scaling arguments based on the circulation discharged into the near wake are proposed to explain the differences. The relationship between flow topology and turbulence is also considered with vorticity saddles and streamline saddles being distinguished. While general agreement with previous studies of flow around a circular cylinder is found with regard to essential flow features in the near wake, some previously overlooked details are highlighted, e.g. the possibility of high Reynolds shear stresses in regions of peak vorticity, or asymmetries near the streamline saddle. The base region is examined in more detail than in previous studies, and vorticity saddles, zero-vorticity points, and streamline saddles are observed to differ in importance at different stages of the shedding process.
649 citations
TL;DR: In this paper, the flow field around surface-mounted, prismatic obstacles with different spanwise dimensions was investigated using the crystal violet, oil-film and laser-sheet visualization techniques as well as by static pressure measurements.
Abstract: The flow field around surface-mounted, prismatic obstacles with different spanwise dimensions was investigated using the crystal violet, oil-film and laser-sheet visualization techniques as well as by static pressure measurements. The aim of this study is to highlight the fundamental differences between nominally two-dimensional and fully three-dimensional obstacle flows. All experiments were performed in a fully developed channel flow. The Reynolds number, based on the height of the channel, lay between 8 X 10[sup 4] and 1.2 X 10[sup 5]. Results show that the middle region of the wake is nominally two-dimensional for width-to-height ratios (W/H) greater than 6. The separated region in front of wider obstacles is characterized by the appearance of a quasi-regular distribution of saddle and nodal points on the forward face of the obstacles. These three-dimensional effects are considered to be inherent to such separating flows with stagnation.
557 citations
TL;DR: In this article, the authors compared LES and RANS calculations of vortex sheddingding flow past a square cylinder at Re = 22.000 and of the 3D flow past the surface-mounted cube at Re < 40.000.
543 citations