A Two-Scale Second-Moment One-Point Turbulence Closure

Stawiarski, Kamil; Hanjalić, K.

doi:10.1016/b978-008044114-6/50008-9

Cited by 4 publications

(3 citation statements)

References 9 publications

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“…Both eddy viscosity and Reynolds stress transport schemes were considered for both STS and TTS models. The results confirmed the expectation of possible improvements in predicting non-equilibrium flows by the TTS models, as also indicated by Hanjalic et al (1980), Wilcox (1988), Kim and Chen (1989), Kim (1991), Chen and Guo (1991), Kim and Benson (1992), Duncan et al (1993), Nagano et al (1997), Rubinstein (2000), Stawiarski and Hanjalic (2002), Cadiou et al (2004) and Stawiarski and Hanjalic (2005) who either developed or used TTS models to predict non-equilibrium flows. The aforementioned works comprised different features of turbulence modelling, such as eddy viscosity and Reynolds stress transport schemes and low Reynolds number approaches.…”

Section: Introductionsupporting

confidence: 87%

“…The modelling process in this work starts by applying the above equations to asymptotic analysis of homogeneous shear flows, decaying grid turbulence and local equilibrium boundary layer flows. These are standard type of solutions which can be found in turbulent flow theory (for example, Pope (2000) and Tennekes and Lumley (1972)) and have also been used for turbulence model tuning in a number of works (Kim and Benson, 1992;Nagano et al, 1997;Stawiarski and Hanjalic, 2002;Cadiou et al, 2004;Stawiarski and Hanjalic, 2005). This process results in a set of constraint equations which ensure that the models return the expected behaviour in these basic standard cases.…”

Section: Turbulence Modellingmentioning

confidence: 99%

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The development and application of two-time-scale turbulence models for non-equilibrium flows

Klein

Craft

Iacovides

2018

International Journal of Heat and Fluid Flow

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This study re-visits the largely overlooked, but highly promising, topic of multi-scale RANS modelling for non-equilibrium turbulent flows. The paper presents the development of RANS models which, at an effective-viscosity level, involve two transport equations for the turbulent kinetic energy; one for the energy of the large scale, energy-producing, eddies and one for that of the smaller eddies, which, through continuous break-up, transfer turbulence energy to the dissipative scales. Two transport equations for the transfer-rate of the turbulent kinetic energy are also necessary, one for the rate of energy transfer from the large to the smaller scales and one for the rate of transfer from the smaller to the dissipative scales, the latter being of course the dissipation rate of turbulence. The two-timescale model of Hanjalic et al. (1980) has been the starting point of the current developments. The coefficients of the terms which appear in these models have been determined from asymptotic analyses of decaying grid turbulence, homogeneous shear flows and local-equilibrium boundary-layer flows. The models were subsequently further developed to become more responsive to strong non-equilibrium features, such as those caused by strong shear. It has been identified that in general, models which have been optimised to satisfy equilibrium flows (as is usually done) are unable to capture the strong changes the flows are subjected to due to highly non-equilibrium effects, thus needing further development. Within the two-timescale framework, it has been found possible to overcome this problem, by exploiting the additional information available on the turbulence spectrum. In a further departure from the development of earlier effective-viscosity two-time scale models, here the eddy viscosity expression is made sensitive to the local strain rate, as was also the case in single-scale models developed by Craft et al. (1996). The original contribution of this research is the development of two widely tested two-timescale linear-eddy-viscosity models, referred to here as NT1 and NT2. The difference between these two models is primarily in the eddy viscosity formulation. The two resulting models have been tested over nine test cases and their performance has been compared to those of the standard high-Reynolds number k − ε model, the SSG Reynolds stress transport model and the two-timescale model of Hanjalic et al. (1980). The test cases comprise of homogeneous shear and normally strained flows, adverse-pressure-gradient, favourable-pressure-gradient and oscillatory boundary layer flows, fully developed oscillatory and ramp up pipe flows and steady and pulsated backward-facing step flows. The models proposed here show considerable promise. They perform well in all cases tested and provide clear improvements over a range of single-and multi-scale models tested in an earlier study (Klein et al., 2015), over a set of test cases which cover a wide range of physical flow phenomena. Moreover, these improvements are achieved without any ...

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Section: Introductionsupporting

confidence: 87%

Section: Turbulence Modellingmentioning

confidence: 99%

The development and application of two-time-scale turbulence models for non-equilibrium flows

Klein

Craft

Iacovides

2018

International Journal of Heat and Fluid Flow

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“…Moreover, while the relative performance of the numerous turbulence models available have been investigated extensively in statistically steady flows, their ability to close successfully the phase-averaged equations in periodic flows have received much less attention, and generally for modified versions of the models (Tardu and Da Costa, 2005;Stawiarski and Hanjalić, 2002;Bremhorst et al, 2003;Lardeau and Leschziner, 2005). Therefore, a workshop dedicated to the evaluation of modelling strategies in statistically periodic flows was recently organized Sellers and Rumsey, 2004).…”

Section: Introductionmentioning

confidence: 97%

Turbulence modelling of statistically periodic flows: Synthetic jet into quiescent air

Carpy

Manceau

2006

International Journal of Heat and Fluid Flow

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Computations of a 2D synthetic jet are performed with usual RANS equations solved in time-accurate mode (URANS), with the standard k-e model and the Rotta + IP second moment closure. The purpose of the present work is to investigate the ability of these standard turbulence models to close the phase-averaged Navier-Stokes equations. Results are compared with recent experiments by Yao et al. made available to the CFD Validation of Synthetic Jets and Turbulent Separation Control workshop held in Williamsburg in 2004. Comparisons of the performance of the models with experimental data show that the evolution of the vortex dipole generated by inviscid mechanisms is not correctly reproduced by the k-e model. The Reynolds-stress model gives much more realistic predictions. However, several characteristics are not well predicted, as for instance the convection velocity. A detailed analysis shows that the vortex dipole dynamics is essentially inviscid during the early blowing phase, when the flow is more transitional than fully turbulent. Turbulence develops and influences the dynamics of the vortices only at a later stage of the blowing phase. Consequently, it is of importance that the turbulence models do not predict erroneously high levels of turbulence. In particular, the present study shows that the correct prediction of the region of negative production that appears during the deceleration of the blowing velocity, due to the misalignment of the strain and anisotropy tensors, is crucial. Therefore, linear eddy-viscosity models must be discarded for this type of pulsed flows, in particular for flow control using synthetic jets.

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Modeling and Simulation of Turbulent Flows

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A Two-Scale Second-Moment One-Point Turbulence Closure

Cited by 4 publications

References 9 publications

The development and application of two-time-scale turbulence models for non-equilibrium flows

The development and application of two-time-scale turbulence models for non-equilibrium flows

Turbulence modelling of statistically periodic flows: Synthetic jet into quiescent air

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