2004•Transactions of the Korean Society of Mechanical Engineers BRequires access
Effects of Freestream Turbulence Intensity on the Flow Past a Circular Cylinder
Jong-Yeon Hwang, Kyung Soo Yang, Sung Su Lee, Joon Sik Lee, Sang San Lee
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Abstract
In this study, the effects of freestream turbulence intensity on laminar-turbulent transition of separated shear layers In the wake of a circular cylinder are Investigated using an immersed boundary method and LES. It is shown that the present numerical results Without freestream turbulence for Re=3,900 based on bulk mean velocity and the cylinder diameter are In good agreement With other authors' experimental observations and numerical results, verifying our numerical methodology. Then a 'prescribed power spectrum method is Imposed to generate isotropic turbulence at the mlet of the computational domain at each time step The principal effects of freestream turbulence Intensity on flow statistics are investigated for Re=3,900 Statistical study reveals that the Reynolds stresses in the near-wake region gradually Increase, and transition occurs further upstream, as the turbulence intensity Increases. On the other hand, the bubble Size behind the cylinder decreases as the turbulence Intensity increases, which indicates that the freestream turbulence helps mean velocity be quickly recovered