Fig 3.12: Picture of the Laskin nozzle seed generator


Fig 3.13: Schematic of the Laskin nozzle used for the seeding generation

An important source of error in velocity measurement is the particle weight. The following analysis ascertains that particle weight is not a major consideration in the present experiments in the sense that particles would follow the main flow without excessive slip. The approach is to find the settling velocity of the particles under a gravity field. Assuming that Stokes law of drag is applicable, the settling velocity is given by

Here and are the particle diameter and density respectively, and and are the fluid viscosity and density respectively. Particles are suitable as long as is negligible compare to actual fluid velocity. For the present set experiments, was estimated to be 0.014 m/s.