Visualization of the Curvature Distorted Internal Flow of an Acoustically Levitated Droplet

抄録

The use of levitated droplets with electrostatic and ultrasonic fields has attracted much attention in the fields of materials development, chemical engineering, and so on. In order to use them properly, it is essential to understand the internal and external flow of the suspended droplets. The flow inside fluid droplets is visualized with the particle image velocimetry (PIV) method. The fluid that is to be investigated is scattered with small particles that follow the flow well. One problem that occurs when the PIV method is used to measure velocity fields inside droplets is however that light refracts at the droplet surface and the internal flow curvature is distorted. The aim of this research is to visualize the curvature distorted internal flow of an acoustically levitated droplet. The curvature distortion is successfully visualized using the PIV approach based on the calibration method. In this study, the curvature distortion illustration was performed based on the refractive indexes and aspect ratio. The experimental results showed that the internal flow curvature can be distorted in two types such as barrel, pincushion distortions, and increase as the refractive index increases.