An important design consideration in two-phase pipe flow of solid-liquid mixtures is the terminal settling velocity below, which the flow becomes unstable and eventually the pipe becomes clogged. On the basis of extended transportation tests, the terminal settling velocity of a solid particle in the rest water given by

vL=FL√2gD(S−1),

where FL is an experimental coefficient, g the gravitational acceleration, D the pipe diameter, and S the specific gravity of solid particle.

What is the dimension of FL? Is this equation dimensionally homogeneous?