低レイノルズ数領域における球形気泡の上昇速度

抄録

Drag coefficients of a spherical rising gas bubble were estimated experimentally and numerically. We developed an experimental apparatus in which a CCD camera with a microscope follows the rising bubble and used it to precisely estimate the drag coefficients of the bubble below Reynolds number of 100 by measurement of the bubble size and the terminal velocity. We also estimated numerically drag coefficients of a gas bubble in an infinite liquid by directly solving a Navier-Stokes equation. The experimental results agree well with the numerical results. Moreover, we compared the experimental results with several proposed equations for estimating drag coefficients and determined the region of applicability of each equation. Finally, we proposed an equation for estimation of drag coefficient by correlating with experimental results.