PARTICLE IMAGE/TRACKING VELOCIMETRY AS AN EFFECTIVE, LOW-COST SOLUTION FOR THE STUDY OF SMALL-SCALE HYDRODYNAMIC PROCESSES IN GEOLOGY

Computational techniques such as PIV (Particle Image Velocimetry) and PTV (Particle Tracking Velocimetry) have gained considerable interest in recent years as a non-intrusive method to study hydrodynamic systems. Traditionally, PIV/PTV required sophisticated hardware in order to operate, such as high speed camera, specialized lasers and associated timing and acquisition systems. We developed a method using modified pointer laser, tracer particles, and common higher-frame-rate cameras at a fraction of the cost while being intuitive for everyone to use. We adapt to use PTVlab, an open source tool in MATLAB that provides analysis for experimental flow videos. The particle tracking algorithm from this software contains features such as particle detection, individual particle tracking and labelling capabilities, etc., which also help to quantify the velocity profile, vorticity, shear and strain for the flow system in the entire illuminated flow field. In every experiment, we first place 3D-fabricated objects in the flow, adjust the flow height and speed and then turn on the sheet laser to illuminate the tracer particles in the flume. We then use the high speed camera in a dark room to record videos. For application, this method was proved invaluable for studying the formation process of microbial streamers and was able to quantify how fields of streamers affect the overall boundary layer profiles. We can also effectively describe the formation process of many flow-induced sedimentary structures such as ripples, dunes and anti-dunes. By combining computer software and these straight-forward tools, it is possible to experiment with flows on a low budget and gain an understanding about natural environments with exciting new results.