A Recommended Correction to the kT−kL−ω Transition-Sensitive Eddy-Viscosity Model

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Maurin Lopez ◽  
D. Keith Walters
Keyword(s):  
Turbulent Flows ◽  
Large Scale ◽  
Eddy Viscosity ◽  
Viscosity Model ◽  
Step Test ◽  
Test Cases ◽  
Turbulent Length Scale ◽  
Eddy Viscosity Model ◽  
Natural Modes ◽  
Viscosity Term

A physics-based modification to the kT−kL−ω transition-sensitive eddy-viscosity model is presented. The modification corrects an anomaly related to the physical mechanism of production of laminar kinetic energy for regions far from the wall in fully turbulent flows, by limiting the production of natural modes in the large-scale eddy-viscosity term by a rescale of the wall-limited turbulent length scale. Round jet and backward facing step test cases are used to reveal the relevant issue and to demonstrate that the new modification successfully addresses the problem.

A Three-Equation Eddy-Viscosity Model for Reynolds-Averaged Navier–Stokes Simulations of Transitional Flow

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
D. Keith Walters ◽  
Davor Cokljat
Keyword(s):  
Boundary Layer ◽  
Turbulent Flows ◽  
Eddy Viscosity ◽  
Flow Behavior ◽  
Applied Pressure ◽  
Plate Boundary ◽  
Low Frequency ◽  
Transitional Flow ◽  
Test Cases ◽  
Eddy Viscosity Model

An eddy-viscosity turbulence model employing three additional transport equations is presented and applied to a number of transitional flow test cases. The model is based on the k-ω framework and represents a substantial refinement to a transition-sensitive model that has been previously documented in the open literature. The third transport equation is included to predict the magnitude of low-frequency velocity fluctuations in the pretransitional boundary layer that have been identified as the precursors to transition. The closure of model terms is based on a phenomenological (i.e., physics-based) rather than a purely empirical approach and the rationale for the forms of these terms is discussed. The model has been implemented into a commercial computational fluid dynamics code and applied to a number of relevant test cases, including flat plate boundary layers with and without applied pressure gradients, as well as a variety of airfoil test cases with different geometries, Reynolds numbers, freestream turbulence conditions, and angles of attack. The test cases demonstrate the ability of the model to successfully reproduce transitional flow behavior with a reasonable degree of accuracy, particularly in comparison with commonly used models that exhibit no capability of predicting laminar-to-turbulent boundary layer development. While it is impossible to resolve all of the complex features of transitional and turbulent flows with a relatively simple Reynolds-averaged modeling approach, the results shown here demonstrate that the new model can provide a useful and practical tool for engineers addressing the simulation and prediction of transitional flow behavior in fluid systems.

New eddy viscosity model for computation of swirling turbulent flows

AIAA Journal ◽  
1987 ◽  
Vol 25 (7) ◽  
pp. 1020-1022 ◽  
Author(s):  
Kwang Yong Kim ◽  
Myung Kyoon Chung
Keyword(s):  
Turbulent Flows ◽  
Eddy Viscosity ◽  
Viscosity Model ◽  
Eddy Viscosity Model

scholarly journals Resolvent-based estimation of turbulent channel flow using wall measurements

2021 ◽  
Vol 927 ◽  
Author(s):  
Filipe R. Amaral ◽  
André V.G. Cavalieri ◽  
Eduardo Martini ◽  
Peter Jordan ◽  
Aaron Towne
Keyword(s):  
Large Scale ◽  
Eddy Viscosity ◽  
Pressure Fluctuations ◽  
Turbulent Channel Flow ◽  
Viscosity Model ◽  
Accurate Estimation ◽  
Linear Estimator ◽  
Estimation Errors ◽  
Eddy Viscosity Model ◽  
Logarithmic Layer

We employ a resolvent-based methodology to estimate velocity and pressure fluctuations within turbulent channel flows at friction Reynolds numbers of approximately 180, 550 and 1000 using measurements of shear stress and pressure at the walls, taken from direct numerical simulation (DNS) databases. Martini et al. (J. Fluid Mech., vol. 900, 2021, p. A2) showed that the resolvent-based estimator is optimal when the true space–time forcing statistics are utilised, thus providing an upper bound for the accuracy of any linear estimator. We use this framework to determine the flow structures that can be linearly estimated from wall measurements, and we characterise these structures and the estimation errors in both physical and wavenumber space. We also compare these results to those obtained using approximate forcing models – an eddy-viscosity model and white-noise forcing – and demonstrate the significant benefit of using true forcing statistics. All models lead to accurate results up to the buffer layer, but only using the true forcing statistics allows accurate estimation of large-scale logarithmic-layer structures, with significant correlation between the estimates and DNS results throughout the channel. The eddy-viscosity model displays an intermediate behaviour, which may be related to its ability to partially capture the forcing colour. Our results show that structures that leave a footprint on the channel walls can be accurately estimated using the linear resolvent-based methodology, and the presence of large-scale wall-attached structures enables accurate estimations through the logarithmic layer.

A new k-ϵ eddy viscosity model for high reynolds number turbulent flows

1995 ◽  
Vol 24 (3) ◽  
pp. 227-238 ◽  
Author(s):  
Tsan-Hsing Shih ◽  
William W. Liou ◽  
Aamir Shabbir ◽  
Zhigang Yang ◽  
Jiang Zhu
Keyword(s):  
Reynolds Number ◽  
Turbulent Flows ◽  
High Reynolds Number ◽  
Eddy Viscosity ◽  
Viscosity Model ◽  
Eddy Viscosity Model ◽  
High Reynolds
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