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ISSN オンライン: 2642-0554

EVOLUTION OF SUBGRID SCALE BY PARTICLES IN A TURBULENT CHANNEL FLOW OBTAINED FROM LAGRANGIAN MEASUREMENTS

Yohei Sato
Department of System Design Engineering, Keio University, 3−14−1 Hiyoshi, Kohoku-ku, Yokohama, 223−8522, Japan

Anthony D. Paris
Thermosciences Division, Department of Mechanical Engineering Stanford University Stanford, California 94305, U.S.A.

Tomohiko Tanaka
Department of System Design Engineering, Faculty of Science and Technology Keio University 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522; Central Research Laboratory Hitachi, Ltd. 1280 Higashi-Koigakubo, Kokubunji, Tokyo, 1858601, Japan

Koichi Hishida
Department of System Design Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522

要約

Evolution of subgrid scale (SGS) stresses by particles in a fully-developed channel flow was investigated by Lagrangian measurement technique. Digital particle image velocimetry and a high-speed CCD camera mounted on a shuttle moving with particle mean streamwise velocity were used to simultaneously detect particle and fluid information amongst particles. Directional interactions between particles and turbulence were ensured by examinations of the real SGS stresses seen by particle. Turbulence augmentation by particles greater than the Kolmogorov micro scale was induced by regions of the energy backscatter on both sides of particles, which means that particles enhance energy transport from subgrid scales to grid scales. An increase in particle volumetric fraction enhances both the SGS energy dissipation and the amount of energy backscatter control.