Swirling-strength based large eddy simulation of turbulent flow around single square cylinder at low Reynolds numbers

• Published in: Applied mathematics and mechanics Vol. 35; no. 8; pp. 959 - 978
• Main Author: 朱祚金 牛建磊 李应林
• Format: Journal Article
• Language: English
• Published: Heidelberg Shanghai University 01.08.2014
• Subjects: Applications of Mathematics; Classical Mechanics; Computational fluid dynamics; Cylinders; Fluid flow; Fluid- and Aerodynamics; Large eddy simulation; Mathematical Modeling and Industrial Mathematics; Mathematical models; Mathematics; Mathematics and Statistics; Partial Differential Equations; Swirling; Turbulence; Turbulent flow; O35; turbulence intermittency; 65P99; lift and drag coefficient; O29; swirling strength; large scale vortex; 76D05; 76D17
• ISSN: 0253-4827; 1573-2754
• DOI: 10.1007/s10483-014-1847-7

In view of the fact that large scale vortices play the substantial role of momentum transport in turbulent flows, large eddy simulation （LES） is considered as a better simulation model. However, the sub-grid scale （SGS） models reported so far have not ascertained under what flow conditions the LES can lapse into the direct nu-merical simulation. To overcome this discrepancy, this paper develops a swirling strength based the SGS model to properly model the turbulence intermittency, with the primary characteristics that when the local swirling strength is zero, the local sub-grid viscosity will be vanished. In this paper, the model is used to investigate the flow characteris-tics of zero-incident incompressible turbulent flows around a single square cylinder （SC） at a low Reynolds number range Re ∈ [103, 104]. The flow characteristics investigated include the Reynolds number dependence of lift and drag coefficients, the distributions of time-spanwise averaged variables such as the sub-grid viscosity and the logarithm of Kolmogorov micro-scale to the base of 10 at Re=2 500 and 104, the contours of spanwise and streamwise vorticity components at t = 170. It is revealed that the peak value of sub-grid viscosity ratio and its root mean square （RMS） values grow with the Reynolds number. The dissipation rate of turbulent kinetic energy is larger near the SC solid walls. The instantaneous factor of swirling strength intermittency （FSI） exhibits some laminated structure involved with vortex shedding.