Author(s)

H. M. D. Harshani, S. A. Galindo-Torres, A. Scheuermann

Abstract

Particle Image Velocimetry (PIV) is a non-invasive optical measurement technique which has been used for many decades to measure fluid velocity. Conventionally, PIV systems are equipped with a laser system for illuminating the flow field. However, laser systems are expensive, and their usage usually creates specific safety precautions. In this work, we used a low cost LED based illumination system in conjunction with the refractive-index matching method to measure flow velocities in porous media. Hydro jelly beads were used as a transparent porous medium which have the same refractive index as water. The movement of tracer particles which were illuminated by the LED pulse was captured by a high-speed double pulsed camera and the resulting images were processed for receiving the pore-scale fluid velocity. Interstitial velocity vectors averaged over a specified region were presented and compared with the vertical velocity component calculated from the volumetric flow rate. In general, our results demonstrated the usability of LED based PIV system for investigating flow conditions in porous media. The future aim of this study is the investigation of micro-scale seepage induced internal erosion of granular structures.

Keywords

Particle Image Velocimetry, porous flow, refractive index matching, image analysis