Journal article
LES and DES Investigations of Turbulent Flow over a Sphere at Re = 10,000
Flow, Turbulence and Combustion, Vol.70(1), pp.267-298
01/2003
DOI: 10.1023/B:APPL.0000004937.34078.71
Abstract
Large Eddy Simulation (LES) using a dynamic Smagorinsky type subgridstress (SGS) model and Detached Eddy Simulation (DES) are applied toprediction and investigation of the flow around a sphere at a Reynoldsnumber of 104 in the subcritical regime. In this regime the boundarylayers at separation are laminar, and transition to turbulence occursfarther downstream in the separated shear layers via Kelvin–Helmholtz(K–H) instabilities. The dynamic eddy viscosity model of Germano et al.(Physics of Fluids
3 (1991) 1760–1765) is used in the LES, while the current implementation of the DESemploys a formulation based on the Spalart–Allmaras (S–A) model. DES isa hybrid approach in which the closure is a modification to theproduction/destruction term of the original Reynolds-AveragedNavier–Stokes (RANS) model, reducing to RANS in the attached regions,and to LES away from the wall. In the present work where we simulate theflow over a sphere in the subcritical regime in which the boundarylayers at separation are laminar, DES can be viewed as LES with adifferent SGS model. Effects of the discretization scheme used toapproximate the convective terms are considered, along with sensitivityof predictions to changes in the additional model coefficient, C
DES, in the DES formulation. DES and LES yield similar predictions of the wakestructure, large-scale vortex shedding and the Strouhal numberassociated with the low frequency mode in the wake. Predictions ofquantities such as the drag coefficient, wake frequencies, position oflaminar separation on the sphere, and the mean pressure andskin-friction distributions along the sphere are in good agreement withthe measurements of Achenbach (Journal of Fluid Mechanics
54 (1972) 565–575). Predictions of the primaryReynolds shear stress, turbulent kinetic energy, eddy viscosity, andturbulent dissipation for the two models are also similar. In addition,both models successfully resolve the formation of the vortex tubes inthe detached shear layers along with the value of the Strouhal numberassociated with the high frequency instability mode, provided that thelevel of numerical dissipation introduced by the discretization schemeremains sufficiently low. Flow physics investigations are focused onunderstanding the wake structure in the subcritical regime.
Details
- Title: Subtitle
- LES and DES Investigations of Turbulent Flow over a Sphere at Re = 10,000
- Creators
- G.S Constantinescu - Stanford University Stanford CA 94305-3030 U.S.AK.D Squires - Mechanical and Aerospace Engineering Department Arizona State University Box 876106 Tempe AZ 85287-6106 U.S.A
- Resource Type
- Journal article
- Publication Details
- Flow, Turbulence and Combustion, Vol.70(1), pp.267-298
- Publisher
- Kluwer Academic Publishers; Dordrecht
- DOI
- 10.1023/B:APPL.0000004937.34078.71
- ISSN
- 1386-6184
- eISSN
- 1573-1987
- Language
- English
- Date published
- 01/2003
- Academic Unit
- Civil and Environmental Engineering
- Record Identifier
- 9983992052402771
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