Flow visualization and quantitative velocity measurements are the foundations of experimental fluid mechanics. Some of the most used visualization techniques include Laser Induced fluorescence (LIF), Shadowgraphy and Schlieren imaging, among others. These techniques provide a visual description of scalar quantities, but they lack the ability to describe velocity fields in detail. Over the last 30 years, Particle Image Velocimetry (PIV) has become the most powerful tool to study velocity fields. The success of this technique has been driven by the rapid development of CCD and CMOS image sensors. This sensor development has led to great advancements, from planar PIV to Stereoscopic-PIV and most recently with the introduction of Tomographic-PIV producing Three-Dimensional, Three-Components velocity fields. In the latest technique the larger hardware cost arises from the need for multiple specialized scientific cameras and the illumination lasers. In this work, we tackle this disadvantage with novel and inexpensive alternatives.
The first part of this work proposes the use of multiple smartphone cameras illuminated by High-Power LED’s in a backlit configuration, initially recording three instants in a single picture. This technique is then expanded to a High-Speed time resolved system using novel smartphone sensors capable of recording video at 960 fps during a larger time sequence. In both cases, similar results to a specialized Stereoscopic and Tomographic PIV system are achieved at a fraction of the cost.
Furthermore, this work proposes to reduce the complexity and cost of a Tomo-PIV system, by using a single camera to reconstruct the Three Dimensional position of seeding particles illuminated by structured light. A first proposition includes chromatic structured light, encoding the depth of every particle in its Hue recorded value. As an alternative, monochromatic light is used to encode the depth position in the intrinsic brightness of each particle. The use of a consumer grade projector allows us to structure light in time to increase the depth resolution of the system.
Andrés became a PhD student in Mechanical Engineering in 2014 at KAUST. He is part of the High Speed Fluids Imaging Lab of Professor Siggi Thoroddsen. Before joining the PhD program, he worked for Saudi Aramco Base Oil Company as a Mechanical Engineer in the Maintenance Department. He obtained his Master’s degree from KAUST in 2012 and Bachelor’s Degree in Mechanical Engineering from Monterrey Institute of Technology and Higher Education in Mexico, 2010. His research is focused on developing alternative fluid visualization and measurement techniques.