The issue of numerical study of turbulent flow over a circular cylinder for different Reynolds numbers has been studied over almost 20 years. During those two decades, there have been successes and failures in the numerical models. This paper presents the implementation of the method of large eddy simulation (LES) to solve the problem of the external flow over a cylinder under a subcritical Reynolds number (Re = 1.4E +5). The purpose is to evaluate the performance of a computational method and complement experimental and numerical data presented in the literature, this as part of a research work which attempts to explain a method of passive drag reduction.

1. LARGE EDDY SIMULATION OF THE FLOW OVER A
CIRCULAR CYLINDER AT A HIGH REYNOLDS NUMBER
Francisco M. Castillo Acosta1, Alejandro Alonzo García2, Claudia Gutiérrez Torres3, José Jesús Martínez Cedillo4
LABINTHAP – SEPI – ESIME – IPN & LS–UI-ESIME TIC–IPN
Laboratorio de Ingeniería Térmica e Hidráulica Aplicada & Laboratorio de Simulación
1
fmedardo@ipn.mx, 2alejandro_1980@hotmail.com, 3cgutierrezt@ipn.mx, 4 jmartinezcedillo@gmail.com
ABSTRACT
The issue of numerical study of turbulent flow over a circular cylinder for
different Reynolds numbers has been studied over almost 20 years. During those
two decades, there have been successes and failures in the numerical models. This
paper presents the implementation of the method of large eddy simulation (LES) to
solve the problem of the external flow over a cylinder under a subcritical Reynolds
number (Re = 1.4E +5). The purpose is to evaluate the performance of a
computational method and complement experimental and numerical data presented
in the literature, this as part of a research work which attempts to explain a method
of passive drag reduction.
NUMERICAL TECHNIQUE
In the LES technique, large-scale movements of the flow are calculated directly as
DNS; while the effects of smaller universal scales are modeled using the
subgrid scale models (SGS). You can idealize LES as an implementation of DNS
in the largest scales, and modeling of the smallest scales by the RANS approach.
However, there are differences in the performance of LES and RANS techniques.
In RANS, the models are based on temporally averaged governing equations;
therefore, the scheme is not able to capture non-stationary behavior and the
dynamics of small scales accurately, because the average amount that fluctuates is
taken to zero . While in the LES technique, the flow structures that are
larger than a given filter size are considered explicitly, while the influence of
unresolved scales is modeled using a SGS model.
COMPUTATIONAL DOMAIN AND BOUNDARY
CONDITIONS
The meshing of the computational domain and boundary conditions are shown in
Figure 3, where D = 1m.
CONCLUSIONS
In general, the LES model was able to simulate the complex nature of the flow at
this high Reynolds number.
Flow characteristics as pressure distribution, dimensionless
Computational domain. shear coefficients and the separation point flow match closely with the values
reported experimentally.
The B.C. used at the inlet was velocity inlet. For this condition, predetermined However, some other features such as the average drag coefficient could not
random fluctuations in the method of the intensity fluctuations and the hydraulic be reproduced successfully.
diameter, whose values were fixed to 20% to 3.63m in order to reproduce the As a recommendation, it’s necessary to improve the mesh quality especially in the
behavior of turbulent flow at the input. Before implementing the LES technique, the near wall zone.
k-w model was applied for 1000 iterations to provide appropriate initial
conditions and improve convergence time. BIBLIOGRAPHY
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3 and velocities in "x" "y" and "z" in the order of 10E-5. University Press. PP.163-198. 1997.
[3] Mittal, "Large eddy simulation of flow past a circular cylinder". Centre for
turbulence research. Annual briefs. 1995.
[4] Breuer M. "A challenging test case for large eddy simulations: high Reynolds
number circular cylinder flow". International Journal of heat and fluid flow. Vol. 21.
PP. 648-654. 2000.
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