Discussion of “Accelerated motion of a spherical particle”

In considering the accelerated motion of spheres in a viscous fluid, the author has restricted himself to consideration of only simple harmonic motions of the fluid field and the sphere. The author's equation of motion (Eq. 11) for a suspended sphere is true only when the solution yields a relative displacement (x ‐ a) which is sinusoidal in time. Otherwise, the apparent mass factor k, and the damping coefficient A have no meaning, because they are both based on the Stokes solution for an oscillating sphere given in LAMB [1945, see References at end of published paper, p. 721]. Both k and A are functions of the circular frequency w as they are defined by (1), (2), and (3).