Interstitial flow field measurements of a monochromatic wave in a two-dimensional, rectangular, non-staggered porous structure

Abstract

In this study the velocity field measurement of monochromatic waves traversing an idealised porous medium was conducted. A two-dimensional, rectangular porous structure was built from timber beams and arranged in a non-staggered array. The structure was placed inside a glass wave flume where the interaction of a monochromatic wave with the porous structure was observed. The portion of the array that was below the waterline, were divided into overlapping regions, each of which were carefully seeded in a sequential manner with neutrally buoyant microspheres. The region being measured was illuminated with an LED light source and filmed with a high speed video camera. The water levels inside the porous structure were simultaneously measured with capacitance probes. The recorded images from the high speed camera, were processed and analysed with image processing and PIV techniques to derive a velocity field for one wave cycle at each region. The velocity fields at all the regions were combined to obtain the best estimate of the flow field through the entire porous structure for one wave cycle.