Migration velocities of spherical solid particles near a vertical wall for Reynolds number from 0.1 to 5

Migration velocities of spherical, solid particles suspended in silicon oil near a vertical wall were measured for Reynolds number, Re<5 (Re=2RU/nu, R is the particle radius, U is the sedimentation velocity, and nu is kinematic viscosity). The sedimentation velocity and the distance between the particle and the wall were measured as a function of time and the lateral migration velocity calculated. The migration velocity was also estimated by assuming that for the flow disturbance produced by the particle, the wall lies in either the Stokes or Oseen regions. The results indicate that as the particle migrates away from the wall, that the velocity components parallel to and normal to the wall transit from the Stokes to the Oseen regions. The results also show that the deviation of the calculated values from the measured values increases as Re increases. Empirical equations are proposed to estimate the velocities parallel to and normal to the wall for Re<5. (C) 2004 American Institute of Physics.