A New Particle Image Velocimetry Technique for Three-Dimensional Full Field Fluid Flow Measurement in Evaporating Films

A novel full field three-dimensional fluid flow measurement technique was developed and applied to the near-contact-line region of a heated and evaporating meniscus. This technique used a single fixed camera and partially coherent light source to image particles seeded in the liquid. Particle centroid positions parallel to the focal plane of the lens were used to establish velocities in this plane. Particle velocities normal to the focal plane were determined by observing the change in diffraction patterns present in the image plane resulting from light scattered and transmitted by the particles. This microscale velocity measurement technique was shown to be capable of measuring velocity fields to within a spatial resolution of m along an optical axis and within m perpendicular to the optical axis with the hardware used in this research. Furthermore, this velocity measurement technique allowed for the simultaneous measurement of the apparent contact angle of an extended meniscus and curved thin liquid film thickness, offering exciting ramifications for use as a tool to study a multitude of dynamic contact line problems