Computations of shear driven vortex flow in a cylindrical cavity using a modified k-ε turbulence model

Saqr, Khalid M.; Aly, Hossam S.; Kassem, Hassan; Sies, Mohsin M.; Wahid, Mazlan Abdul

doi:10.1016/j.icheatmasstransfer.2010.06.021

Cited by 29 publications

(21 citation statements)

References 40 publications

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“…The computational model predicted the vortex action resulting from the shear driven flow, however with slight over predictions of velocity in the near wall regions due to the use of the logarithmic law of the wall. The results of the validation case agree well with previous published simulations of turbulent shear driven cavity flows using the R ε /k-ε model for a wide range of Reynolds number [16]. Figure 6 shows the profiles of normalized U x and U y velocity components as plotted on line (a-a) for square cavity with different opening ratios as given in tab.…”

Section: Model Validationsupporting

confidence: 85%

“…It represents shear driven flow inside a partially open cylindrical cavity, fixed on the trailing edge of a flat plate. A complete computational analysis of such case has been previously reported by Saqr et al [16]. Figure 5 shows a comparison between numerical results and LDV measurements.…”

Section: Model Validationmentioning

confidence: 80%

“…Their work has mainly aimed at comparing three sub-grid scale turbulence models, namely the S-A, SST k-ω, and the realizable k-ε models. Saqr et al [16] have conducted CFD investigation of turbulent flow over a partially-open circular cavity using the R ε /k-ε turbulence model. The main objective of their work was to test the additional source term in the ε equation, which represents local anisotropy.…”

Section: Introductionmentioning

confidence: 99%

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Numerical investigation of turbulent flow and heat transfer over partially open cavities: Effect of opening ratio

2017

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Partially open cavities are encountered in various engineering systems such as electronic cooling devices and cooling for gas turbine blades, instead of conventional film cooling slots. Flow is to be imparted over the partially open cavity where it induces a shear layer and a shear driven vortex within the cavity, which is subjected to cooling effect at its wall. Depending on the opening ratio, heat and mass transfer occur between the main flow and the trapped vortex through the shear layer. In the present study, RANS simulations of such flow have been conducted for circular and square cavities to investigate the effect of opening ratio on the heat and mass transfer characteristics. The simulations were established on a rigorous numerical approach and proper validation with laser Doppler velocimetry measurements of turbulent flow in circular cavity. Based on the hydraulic diameter of the cavity, opening ratios ranging from 0.2 to 1.0 were investigated for a Reynolds number of 3?105. Generally, the maximum Nusselt number was achieved at higher opening ratios for both circular and rectangle cavities. On the other hand, the maximum dimensionless temperature gradient, ?, inside the cavity was achieved at L/D = 0.2 for both cavity configurations.

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Section: Model Validationsupporting

confidence: 85%

Section: Model Validationmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

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Numerical investigation of turbulent flow and heat transfer over partially open cavities: Effect of opening ratio

2017

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“…Hence, although the isotropy assumption might lead to an intuition that turbulence viscosity predictions should not be accurate, extensive numerical investigations utilizing these models have yielded successful predictions of complex flows. Examples on the success of eddy viscosity models in predicting different types of vorticity-dominated flow and flow with streamline curvature can be found in [179][180][181][182][183][184][185][186][187][188][189][190]. LES [191] provides an alternative approach in which the large eddies are computed in a time-dependent simulation that uses a set of filtered equations.…”

Section: Turbulent Viscosity Modelsmentioning

confidence: 99%

Wells turbine for wave energy conversion: a review

Shehata

Xiao

Saqr

et al. 2016

Int. J. Energy Res.

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Summary In the past 20 years, the use of wave energy systems has significantly increased, generally depending on the oscillating water column concept. Wells turbine is one of the most efficient oscillating water column technologies. This article provides an updated and a comprehensive account of the state‐of‐the‐art research on Wells turbine. Hence, it draws a roadmap for the contemporary challenges, which may hinder future reliance on such systems in the renewable energy sector. In particular, the article is concerned with the research directions and methodologies, which aim at enhancing the performance and efficiency of Wells turbine. The article also provides a thorough discussion of the use of CFD for performance modeling and design optimization of Wells turbine. It is found that a numerical model using the CFD code can be employed successfully to calculate the performance characteristics of W‐T as well as other experimental and analytical methods. The increase of research papers about CFD, especially in the last 5 years, indicates that there is a trend that considerably depends on the CFD method. Copyright © 2016 John Wiley & Sons, Ltd.

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“…The signifi cant difference in results of numerical modeling of circulating fl ow in the circular cavity on the wall of a rotating channel [1] from the corresponding data obtained with the Doppler laser velocimeter on the experimental setup in Southampton [2] increasingly draws attention to the idea of correction of semiempirical turbulence models used to close Reynolds-averaged Navier-Stokes equations [3] with account of the infl uence of the streamline curvature.…”

mentioning

confidence: 99%

Correction of the Shear-Stress-Transfer Model with Account of the Curvature of Streamlines in Calculating Separated Flows of an Incompressible Viscous Fluid

Исаев

Baranov²,

Zhukova

et al. 2014

J Eng Phys Thermophy

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The necessity of correcting differential semiempirical turbulence models to calculate circulating fl ows of an incompressible viscous fl uid is discussed. Approaches to taking account of the infl uence of the curvature of streamlines on turbulence characteristics arereviewed. Experience gained in modeling numerically twodimensional separated fl ows in a square and a cylindrical cavity on the wall of a plane-parallel channel is analyzed; an additional semiempirical constant in the expression for vortex viscosity of a modifi ed shear-stress-transfer model is substantiated.Introduction. The signifi cant difference in results of numerical modeling of circulating fl ow in the circular cavity on the wall of a rotating channel [1] from the corresponding data obtained with the Doppler laser velocimeter on the experimental setup in Southampton [2] increasingly draws attention to the idea of correction of semiempirical turbulence models used to close Reynolds-averaged Navier-Stokes equations [3] with account of the infl uence of the streamline curvature.In this connection, the present work seeks to analyze experience gained in modeling numerically separated fl ows with turbulence models, in particular, with the frequently used semiempirical turbulence model, i.e., the Mentershear-stresstransfer k-ω model (MSST) in the versions of the year 1993 (MSST1993) and of the year 2003 (MSST2003) [4, 5]. Also, the present work seeks to substantiate the semiempirical constant in the expression for vortex viscosity in the MSST 2003 version [5] using, as examples, the calculations of experimental analogs of separated fl ows of an incompressible viscous medium in a square and a cylindrical cavity on the wall of a plane-parallel channel.Historical Review of Investigations into the Correction of Semiempirical Turbulence Models with Account of the Infl uence of the Streamline Curvature. It is common knowledge that semiempirical models of closure of Reynoldsaveraged Navier-Stokes equations [3, 6] have been constructed for calculation of wall fl ows. In any event, calibration of the constants for them is based on measurements that have been performed on special test beds for model fl ows [7]. Turbulence models are not universal. Thus, the turbulent Prandtl number for the boundary layer is equal to 0.9, and for the jet fl ow, to 0.6 [8]. At the same time, in intricate wall fl ow, one cannot, in practice, single out jet fl ows and, in modeling them using package technologies, takes the turbulent Prandtl number as constant and equal to 0.9 [9]. Also, it should be noted that algebraic turbulent models for calculation of fl ows in curvilinear channels include curvature corrections in expressions for a turbulence scale [3]. Rotation corrections seem even more signifi cant as far as their infl uence, primarily, on velocity profi les is concerned [10].

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Computations of shear driven vortex flow in a cylindrical cavity using a modified k-ε turbulence model

Cited by 29 publications

References 40 publications

Numerical investigation of turbulent flow and heat transfer over partially open cavities: Effect of opening ratio

Numerical investigation of turbulent flow and heat transfer over partially open cavities: Effect of opening ratio

Wells turbine for wave energy conversion: a review

Correction of the Shear-Stress-Transfer Model with Account of the Curvature of Streamlines in Calculating Separated Flows of an Incompressible Viscous Fluid

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