Full-field convection flow visualization in pendant droplets by tilt-angle imaging

The flow field in a droplet can be distorted as the light passes through a convex liquid-vapor interface in the measurement of Particle Image Velocimetry. We have developed a solution from ray tracing to recover the distortion flow in the droplet. A three-dimensional surface model has been applied to a self developed ray tracer to recover the distorted images. By tilting the camera upwards between 10° and 20° in angle, about 95% of the full internal flow vectors of a pendant droplet, especially near the interface, can be recovered to the real positions for further analysis.