Automatic vision system for analysis of microscopic behavior of flow and transport in porous media

This paper describes the development of a novel automated and efficient vision system to obtain velocity and concentration measurements within a porous medium. An aqueous fluid laced with a fluorescent dye or microspheres flows through a transparent, reflective-index-matched column packed with a transparent crystals. For illumination purposes, a planar sheet of lasers passes through the column as a CCD camera records all the laser illuminated planes. Detailed microscopic velocity and concentration fluids have been computed within a 3D volume of the column. For measuring velocities, while the aqueous fluid, laced with fluorescent microspheres, flows though the transparent medium, a CCD camera records the motions of the fluorescing particles by a video cassette recorder.The recorder images are acquired frame by frame and transferred to the computer foe processing by using a frame grabber and written relevant algorithms through an RD-232 interface. Since the grabbed image is poor in this stage, some preprocessings are used to enhance particles within images. Finally, these measurement, while the aqueous fluid, laced with a fluorescent organic dye, flows through the transparent medium, a CCD camera sweeps back and forth across the column and records concentration slices on the planes illuminated by the laser beam traveling simultaneously with the camera. Subsequently, these recorded images are transferred to the computer for processing in similar fashion to the velocity measurement. In order to have a fully automatic vision system, several detailed image processing techniques are developed to match exact imaged (at difference times during the experiments) that have different intensities values but the same topological characteristics. This results in normalized interstitial chemical concentration as a function of time within the porous column