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DNS ON MULTISCALE-GENERATED GRID TURBULENCE USING A CLASSICAL GRID

Hiroki Suzuki
Department of Mechanical Engineering Nagoya Institute of Technology Gokiso-cho, Showa-ku, Nagoya, Japan

Kouji Nagata
Department of Mechanical Science and Engineering, Nagoya University, Nagoya, 464-8603, Japan

Yasuhiko Sakai
Department of Mechanical Science and Engineering, Nagoya University, Nagoya, 464-8603, Japan

Toshiyuki Hayase
Institute of Fluid Science, Tohoku University Sendai 980-8577, Japan

Yutaka Hasegawa
Research Center for Advanced Energy Conversion, Nagoya University Furo-cho, Chikusa-ku, Nagoya 464-8603; Department of Mechanical Engineering Nagaoka University of Technology, Nagaoka, Niigata 940-2133, Japan

Tatsuo Ushijima
Department of Engineering Physics, Electronics and Mechanics, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555

Résumé

We carry out direct numerical simulation of experimental grid turbulence, for which the mesh Reynolds number is 2500. The grid is directly constructed in the computational domain. The streamwise computational domain size is > 100 times the mesh size. The value of the decay exponent n is estimated as n~ 1.36 by using a ratio defined by the turbulent kinetic energy and its dissipation. The prevailing perspective is that the memory of the turbulence cannot be considered as short. In this paper, we propose a promoter that focuses on the generation of turbulence using the grid, not on the shape of the grid, as addressed in previous studies (Hurst & Vassilicos (2007); Krogstad & Davidson (2011)), from a multiscale perspective and investigate the effects of the turbulence-generating method on the decay exponent n. Specifically, n is increased to n ~ 1.53 and 1.41 because of the changes in the initial conditions.