High-order detached eddy simulation, zonal LES and URANS of cavity and labyrinth seal flows

2013 ◽  
pp. n/a-n/a
Author(s):  
Richard J. Jefferson-Loveday ◽  
V. Nagabhushana Rao ◽  
James C. Tyacke ◽  
Paul G. Tucker
Keyword(s):  
Labyrinth Seal ◽  
High Order ◽  
Detached Eddy Simulation ◽  
Eddy Simulation

scholarly journals Enhanced Delayed Detached Eddy Simulation for Cavities and Labyrinth Seals

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Richard J. Jefferson-Loveday
Keyword(s):  
Labyrinth Seal ◽  
High Order ◽  
Experimental Measurements ◽  
Detached Eddy Simulation ◽  
Specific Flow ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
New Variant ◽  
Wide Range ◽  
Original Definition

Abstract A range of popular hybrid Reynolds-averaged Navier–Stokes -large eddy simulation (RANS-LES) methods are tested for a cavity and two labyrinth seal geometries using an in-house high-order computational fluid dynamics (CFD) code and a commercial CFD code. The models include the standard Spalart–Allmaras (SA) and Menter shear stress transport (SST) versions of delayed detached eddy simulation (DDES) and the Menter scale adaptive simulation (SAS) model. A recently formulated, enhanced, variant of SA-DDES presented in the literature and a new variant using the Menter SST model are also investigated. The latter modify the original definition of the subgrid length scale used in standard DDES based on local vorticity and strain. For all geometries, the meshes are considered to be hybrid RANS-LES adequate. Very low levels of resolved turbulence and quasi-two-dimensional flow fields are observed for the standard DDES and SAS models even for the test cases here that contain obstacles, sharp edges, and swirling flow. Similar findings are observed for both the commercial and in-house high-order CFD codes. For the cavity simulations, when using standard DDES and SAS, there is a significant under prediction of turbulent statistics compared with experimental measurements. The enhanced versions of DDES, on the other hand, show a significant improvement and resolve turbulent content over a wide range of scales. Improved agreement with experimental measurements is also observed for profiles of the vertical velocity component. For the first labyrinth seal geometry swirl velocities are more accurately captured by the enhanced DDES versions. For the second labyrinth seal geometry, the mass flow coefficient prediction using the enhanced models is significantly improved (up to 30%). Standard, industrially available hybrid RANS-LES models, when applied to the present canonical cases can produce little to no resolved turbulent content. The standard SA- and Menter-based DDES models can yield lower levels of eddy viscosity when compared to equivilent steady RANS simulations which means that they are not operating as RANS or LES. It is recommended that hybrid RANS-LES models should be extensively tested for specific flow configurations and that special care is exercised by CFD practitioners when using many of the popular hybrid RANS-LES models that are currently available in commercial CFD packages.

A DDES study of the flow past a prolate spheroid using a high-order U-MUSCL scheme

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040075
Author(s):  
Yu-Chen Yang ◽  
Zhen-Ming Wang ◽  
Ning Zhao
Keyword(s):  
Flow Separation ◽  
Vortex Structure ◽  
Prolate Spheroid ◽  
High Order ◽  
Detached Eddy Simulation ◽  
Complex Flow ◽  
Eddy Simulation ◽  
Flow Past ◽  
Delayed Detached Eddy Simulation ◽  
Flow Phenomena

Flow past a prolate spheroid, which is a representative simplified configuration for vehicles such as maneuvering ships, submarines and missiles, comprises a series of complex flow phenomena including pressure-induced flow separation, which results in unsteady forces and movements that may be detrimental to vehicles’ performance. In this paper, a Delayed Detached Eddy Simulation (DDES) method combined with a new high-order U-MUSCL scheme is proposed to more precisely and accurately capture the flow separation and vortex structure. This method is applied to simulate the aerodynamic performance of the 6:1 prolate spheroid at an AOA of [Formula: see text] with the Reynolds number of [Formula: see text]. Axial pressure distribution of five individual chord wise sections and flow field structure of the aft body are analyzed. Numerical results agree well with the experimental data. It can be concluded that DDES combined with three-order U-MUSCL scheme demonstrates reliable performance since it captures the vortex structure of aft body distinctly and predicts the separation and reattachment points of the secondary vortex precisely.

scholarly journals Delayed detached Eddy simulation of wing flutter boundary using high order schemes

2017 ◽  
Vol 71 ◽  
pp. 199-216 ◽  
Author(s):  
Jia-ye Gan ◽  
Hong-Sik Im ◽  
Xiang-ying Chen ◽  
Ge-Cheng Zha ◽  
Crystal L. Pasiliao
Keyword(s):  
High Order ◽  
Detached Eddy Simulation ◽  
High Order Schemes ◽  
Wing Flutter ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Flutter Boundary

Delayed Detached Eddy Simulation of Airfoil Stall Flows Using High-Order Schemes

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Hong-Sik Im ◽  
Ge-Cheng Zha
Keyword(s):  
Second Order ◽  
High Order ◽  
Weno Scheme ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
High Order Scheme ◽  
Eddy Simulation ◽  
Naca0012 Airfoil ◽  
Order Scheme ◽  
Fifth Order

An advanced hybrid Reynolds-Averaged Navier–Stokes/large eddy simulation (RANS/LES) turbulence model delayed detached eddy simulation (DDES) is conducted in thispaper to investigate the dynamic stall flows over 3D NACA0012 airfoil at 17 deg, 26 deg, 45 deg, and 60 deg angle of attack (AOA). The spatially filtered unsteady 3D Navier–Stokes equations are solved using a fifth-order weighted essentially nonoscillatory (WENO) reconstruction with a low diffusion E-CUSP (LDE) scheme for the inviscid fluxes and a conservative fourth-order central differencing for the viscous terms. An implicit second-order time marching scheme with dual time stepping is employed to achieve high stability and convergency rate. A 3D flat plate is validated for the DDES model. For quantitative prediction of lift and drag of the stalled NACA0012 airfoil flows, the detached eddy simulation (DES) and DDES achieve much more accurate results than the Unsteady Reynolds-Averaged Navier–Stokes (URANS) simulation. In addition to the quantitative difference, the DES/DDES and URANS also obtain qualitatively very different unsteady stalled flows of NACA0012 airfoil with different vortical structures and frequencies. This may bring a significantly different prediction if those methods are used for fluid–structural interaction. For comparison purpose, a third-order WENO scheme with a second-order central differencing is also employed for the DDES stalled NACA0012 airfoil flows. Both the third- and fifth-order WENO schemes predict the stalled flow similarly for lift and drag at AOA less than 45 deg, while at AOA of 60 deg, the fifth-order WENO scheme shows better agreement with the experiment than the third-order WENO scheme. The high-order scheme of WENO 5 also resolves more small scales of flow structures than the second-order scheme. The prediction of the stalled airfoil flow using DDES with both the high-order scheme and second-order scheme is overall significantly more accurate than the URANS simulation.

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