The Effects of the Wall-Layer Models on the Outer Turbulence Structures in Large Eddy Simulation of Pipe Flows

2007 ◽  
Author(s):  
Makoto Tsubokura ◽  
Yasuo Oto ◽  
Jun Etoh ◽  
Binghu Piao ◽  
Shigeaki Kuroda
Keyword(s):  
Large Eddy Simulation ◽  
Wall Layer ◽  
Detached Eddy Simulation ◽  
Layer Model ◽  
Turbulence Structures ◽  
Pipe Flows ◽  
Eddy Simulation ◽  
Streaky Structures ◽  
Large Eddy ◽  
Shed Light

Reproduction of the outer turbulence in Large Eddy Simulation (LES), when the wall-layer model is adopted in the inner layer, is investigated to validate the hybrid RANS/LES as an approximate near-wall treatment. Special emphasis is on the possibility of Detached Eddy Simulation (DES) for the reproduction of outer large (∼ R) and very large (∼ 10R) streaky structures typically observed in the pipe turbulence. LES and DES of fully developed turbulent pipe flows at the friction Reynolds number up to 5000 are conducted using a very long analysis region to capture entire outer scales. It is found that the outer scales are properly captured in DES independent on the unphysical super-streaks in the RANS region near the wall, as long as sufficient height for the DES buffer layer is maintained. Our results shed light on the origin of the outer structures, which are rather autonomous similar to the inner sublayer streaks, and these two structures with different scaling exists in the isolated manner.

scholarly journals Assessing IDDES-Based Wall-Modeled Large-Eddy Simulation (WMLES) for Separated Flows with Heat Transfer

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 246
Author(s):  
Rozie Zangeneh
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Large Eddy Simulation ◽  
Skin Friction ◽  
Heat Fluxes ◽  
Separated Flows ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Isothermal Wall

The Wall-modeled Large-eddy Simulation (WMLES) methods are commonly accompanied with an underprediction of the skin friction and a deviation of the velocity profile. The widely-used Improved Delayed Detached Eddy Simulation (IDDES) method is suggested to improve the prediction of the mean skin friction when it acts as WMLES, as claimed by the original authors. However, the model tested only on flow configurations with no heat transfer. This study takes a systematic approach to assess the performance of the IDDES model for separated flows with heat transfer. Separated flows on an isothermal wall and walls with mild and intense heat fluxes are considered. For the case of the wall with heat flux, the skin friction and Stanton number are underpredicted by the IDDES model however, the underprediction is less significant for the isothermal wall case. The simulations of the cases with intense wall heat transfer reveal an interesting dependence on the heat flux level supplied; as the heat flux increases, the IDDES model declines to predict the accurate skin friction.

Large Eddy Simulation of the Wake Behind a Turning Ship

2002 ◽  
Author(s):  
Ibrahim Yavuz ◽  
Zeynep N. Cehreli ◽  
Ismail B. Celik ◽  
Shaoping Shi
Keyword(s):  
Large Eddy Simulation ◽  
Sensitivity Study ◽  
West Virginia University ◽  
Vortical Structures ◽  
Turbulence Structures ◽  
Eddy Simulation ◽  
Flow Generation ◽  
Large Eddy ◽  
Unsteady Inflow ◽  
Random Flow

This study examines the dynamics of turbulent flow in the wake of a turning ship using the large eddy simulation (LES) technique. LES is applied in conjunction with a random flow generation (RFG) technique originally developed at West Virginia University to provide unsteady inflow boundary conditions. As the ship is turning, the effects of the Coriolis and centrifugal forces on vortical structures are included. The effects of the Coriolis force on the flow-field are assessed and a grid sensitivity study is performed. The predicted turbulence structures are analyzed and compared with the wake of a non-turning ship.

Overset Grid Method for Large Eddy Simulation of Turbulent Flows Around Bluff Bodies

2007 ◽  
Author(s):  
Y. Itoh ◽  
T. Tamura
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flows ◽  
Grid Method ◽  
Side Surface ◽  
Mass Conservation ◽  
Overset Grid ◽  
Turbulence Structures ◽  
Eddy Simulation ◽  
Side Ratio ◽  
Large Eddy

The large eddy simulation of turbulent flow around a rectangular cylinder with side ratios of 1.0, 2.0, 2.67, and 3.0 at Re = 22000, is carried out using an overset grid system. In order to improve mass conservation along the boundary of computational domains, numerical procedures are proposed. The aerodynamic forces of rectangular cylinders can be predicted numerically. Details of pressure distributions along the side surface of the cylinder and turbulence structures in the wake is discussed, because there is a difference in accuracy of computational results in terms of the side ratio.

Constrained large-eddy simulation of turbulent flow and heat transfer in a stationary ribbed duct

2016 ◽  
Vol 26 (3/4) ◽  
pp. 1069-1091 ◽  
Author(s):  
Zhou Jiang ◽  
Zuoli Xiao ◽  
Yipeng Shi ◽  
Shiyi Chen
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Thermodynamic Quantities ◽  
Detached Eddy Simulation ◽  
Square Duct ◽  
Content Type ◽  
Eddy Simulation ◽  
Flow And Heat Transfer ◽  
Large Eddy

Purpose – The knowledge about the heat transfer and flow field in the ribbed internal passage is particularly important in industrial and engineering applications. The purpose of this paper is to identify and analyze the performance of the constrained large-eddy simulation (CLES) method in predicting the fully developed turbulent flow and heat transfer in a stationary periodic square duct with two-side ribbed walls. Design/methodology/approach – The rib height-to-duct hydraulic diameter ratio is 0.1 and the rib pitch-to-height ratio is 9. The bulk Reynolds number is set to 30,000, and the bulk Mach number of the flow is chosen as 0.1 in order to keep the flow almost incompressible. The CLES calculated results are thoroughly assessed in comparison with the detached-eddy simulation (DES) and traditional large-eddy simulation (LES) methods in the light of the experimentally measured data. Findings – It is manifested that the CLES approach can predict both aerodynamic and thermodynamic quantities more accurately than the DES and traditional LES methods. Originality/value – This is the first time for the CLES method to be applied to simulation of heat and fluid flow in this widely used geometry.

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