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ISSN オンライン: 2642-0554

EQUILIBRIUM PUFFS DO INDEED EXIST: ACCURATE DESCRIPTION BY MEANS OF LONG-WAVE NAVIER-STOKES SOLUTIONS

Vladimir G. Priymak
Institute for Mathematical Modeling, Russian Academy of Sciences Miusskaya Square 4-A, 125047 Moscow, Russia

Teruo Miyazaki
Department of Mechanical Engineering, Kokushikan University 4-28-1, Setagaya, Setagaya-ku, Tokyo 154-8515, Japan

要約

The possibility of intermittent turbulent shear flows description by means of nonstationary long-wave 3D Navier-Stokes solutions is shown in principle. The classical problem of viscous incompressible fluid flows in a circular pipe at transitional Reynolds numbers 1800 ≤ Re ≤ 4000 is taken as a model one. By means of direct numerical simulation we have obtained statistically stationary Navier-Stokes solutions which describe turbulent (at 2500 ≤ Re ≤ 4000), intermittent (at Re = 2200, 2350) and laminar (Re ≤ 2000) flow regimes. Numerical solutions at Re = 2200,2350 describe equilibrium self-sustained flow regimes in which turbulent structures surrounded by almost laminar flow propagate downstream while preserving their length. Thus, theoretical confirmation of the existence of particular transitional flow regimes − so-called equilibrium puffs − is obtained.