Oral Presentation NCGRT/IAH Australasian Groundwater Conference 2019

A novel PIV image processing method for the measurement of preferential flow velocity through rough-walled fractures (95)

Ali Ranjbar 1 , Alexander Scheuermann 2 , Claudia Cherubini 3 , Ling Li 4
  1. Department of Civil and Environmental Engineering, K. N. Toosi University of Technology, Teheran, Iran
  2. School of Civil Engineering , The University of Queensland, Brisbane, QLD, Australia
  3. University of Ferrara, Ferrara, FE, Italy
  4. School of Engineering, Westlake University, Hangzhou, China

Single phase flow in fractured rock is of great importance in different branches of porous media such as oil recovery and water resources management. Velocity field among the apertures is required for modelling and estimation of flow rates within the fracture area. Particle Image Velocimetry (PIV) technique is an efficient tool for analysing the velocity field and its distribution stemmed from the high velocity gradient caused by aperture variations. In this study, the fracture surfaces were generated using a 3D printing technology and moulded using the transparent epoxy resin to trace the preferential flow path and quantify the velocity field using a PIV camera. An experimental apparatus was designed by attaching a small constant head along flow path and then, the PIV-view software was used to measure the velocity vectors in the transient flow condition. To investigate the effect of fracture geometry on velocity distribution, several synthetic fracture surfaces based on different fractal dimensions and mismatch wavelengths were designed and placed with different inclination angles in the experimental set up. The average velocity of preferential flow path for different fractures were compared using an image processing technique indicating that the horizontal velocity increased near the small aperture whereas, the maximum value of the vertical velocity was observed near the large aperture. Moreover, the influence of fracture inclination angle on horizontal velocity field and number of thin preferential channels were significant