Flow characterization through a network cell using particle image velocimetry

Particle image velocimetry (PIV) with refractive index matching was developed to map pore-scale fluid flow through a clear, acrylic two-dimensional network flow cell. A microscope objective lens was incorporated in the PIV set up so that flow in microscale throats could be measured. The flow cell consists of 20 x 20, equal-size cylindrical pore bodies, 2.5 mm in diameter and 1.0 mm in height, connected on a diamond lattice by 2.5 mm long, square cross-section throats of widths that varied randomly among 0.2, 0.6, and 1.0 mm. Micro-PIV data was used to obtain the two-dimensional streamline pattern of fluid flow and the velocity field over the field of view (FOV) by periodically illuminating seed particles following the flow and cross correlating particle positions to determine displacements over time. Refractive index matching of the flow cell and test fluid minimizes extraneous scattering of light at solid-liquid interfaces improving image resolution. Experimentally determined velocity vectors for single-phase flow through three pore bodies and their adjoining throats as well as for the outlet of the flow cell were compared with numerical simulations of flow through the cell.