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ENERGY TRANSPORT MECHANISMS IN PARTICLE-LADEN TURBULENT WATER CHANNEL FLOW

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

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

Resumo

The mechanisms of energy transport by solid particles in a turbulent water channel flow were investigated by a laser measurement technique and large eddy simulation. Particle image velocimetry was employed to detect particle velocities and fluid information amongst particles. A filtering technique was applied to the fluid flow to extract a characteristic length scale that governs the energy transfer from particles to fluid turbulence. Simulations were performed considering directional scale dependency on force coupling method between particles and turbulence, which can predict both turbulence attenuation and augmentation by particles. An increase in streamwise turbulence intensity in the presence of particles is mainly attributed to increasing values of particle-associated term in fluctuating velocity budget. The energy backscatter due to particles was observed at Δ/dp ~ 10 (Δ : filter width, dp : particle diameter) in both experiments and simulations, which indicates that particles affect the eddy motion whose size is approximately ten times particle diameter.