拍動流による室内の微粒子の運動

抄録

The unsteady motion of small particles which are initially uniformly distributed in a square chamber with a pulsating inlet velocity is studied numerically. The force between the particle and fluid is assumed to be proportional to the relative velocity. The problem considered is governed by four parameters: the Reynolds number, the dimension ratio (which characterizes the particles to be coarse or fine), the period and the amplitude of the pulsating inlet velocity (which are made dimensionless). The motion of the particles is classified into three types: the exhaust type, in which the particles are exhausted through the outlet; the circulation type, in which the particles circulate in the chamber; and the adhesion type, in which the particles adhere to the wall of the chamber. The effects of the period and the amplitude of the inlet velocity on the ratio of the number of particles of each type to the total number of particles are examined taking the Reynolds number and the dimension ratio as parameters. The suitable ranges of the period and the amplitude of the inlet velocity, in which the number of the exhausted particles increases and the number of the circulating particles decreases, are found taking the dimension ratio as a parameter. The mechanism on the exhausting of the particle is qualitatively clarified on the basis of the relation between the stream line and the trajectory of the particles.