Dynamics of Granular Flow through a Vertical Pipe : Effect of Medium Flow

概要

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Density waves of granv.rlar patrticles (rough sand) in a vertical pipe are experinaentally investigated under the condition where the naeditrna (air) flow is well controlled. When a cock attachedto the bottoraa-end of the pipe is open, air is dragged by ['alling granular particles and flowstogether with sand. No density waves are observed for this situation. As the cock is gradtzaJJyclosed, however, the pressure gr?tdient of air inside the pipe becomes larger and, as a restmlt, den-sity waves of granular particles emerge. Power spectrtrmn P( f) of tinae series signals of densitywaves shows a clear power-law form P(.f) N f ' and the precise measuretnents indicate thatthe exponent a is close to 4/3. The valtre of cx is robust even tnnder the meditrrn flow as far asdensity waves can be seen.
社団法人日本物理学会の論文
1998-05-15