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COHERENT STRUCTURES AND THEIR CONTRIBUTION TO TURBULENT INTENSITY IN TURBULENT CHANNEL FLOW

Shintaro Imayama
Department of Energy Engineering and Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan; Linne Flow Center, KTH Mechanics, SE-100 44 Stockholm, Sweden

Yoshinobu Yamamoto
Department of Nuclear Engineering, Kyoto University, Yoshida Sakyo-ku, Kyoto 606-8501,Japan

Yoshiyuki Tsuji
KTH Mechanics, Royal Institute of Technology, 100 44 Stockholm, Sweden; Department of Energy Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8503, Japan

Résumé

The measurement of stream-wise turbulent intensity normalized by inner variables is discussed in this paper. The stream-wise turbulent intensity urms normalized by friction velocity uτ which is expressed as, u+rms, is well known to increase with Reynolds number. Especially the trend of peak of u+rms as a function of Reynolds number has been investigated so far by many researchers. In order to clarify the u+rms profile, there are two important issues. One is the accurate velocity measurement. This is discussed from the point of hot-wire resolution. The other is the evaluation of skin friction. We have modified the classical oil-film technique and discuss its accuracy. Experimental results are compared with those of Direct Numerical Simulation (DNS).