Rising Speed of a Spherical Gas Bubble near a Plane Wall

Abstract

Rising speed of a spherical gas bubble near a plane wall was measured experimentally. We developed an experimental apparatus in which a CCD camera with a microscope follows the rising bubble and used it to precisely estimate the change of the rising speed due to the plane wall below Reynolds number of 50. We also proposed the equation for estimating the effect of a plane wall on the drag force by modifying the analytical solution obtained under the Ossen approximation and compared with the experimental results. The results show that the Stokes solution including the wall effect is in good agreement with the experimental results for the Re<0.1. And they also show that the proposed equation agrees well with the experimental results and can be applied for estimating the wall effect on the rising speed up to the Re of 50.