Small container fluid dynamics to produce optimized inspection conditions

The generation of a desired non-linear resonance in the toroidal flow of liquid in a cylindrical injectable product is described. The resulting liquid flow pattern generated with an approximately smooth meniscus is down at the walls, across to the center of rotation, up on the center of rotation, across the meniscus to complete the pattern. The controlled flow pattern results in a predictable location for particle of varying mass and hydraulic shape. This predictability of location transforms the problem of particle detection from a chance occurrence to a deterministic task. The deterministic location of particle position is a contributor to the demonstrated capability to measure the size of visible particle range in a range from 33 mum to 1,000 mum with a median deviation of 1% and a maximum deviation from NIST dimensional accuracy of 3%.