Comparison of PIV measurement and direct numerical simulation of low Reynolds number flow in porous media

Abstract:

Two different experimental and computational methods implemented to investigate the flow through porous media. The porous media flow is a highly demanding field in industry and academia that has not been largely studied due to its complexities based on multi-phase geometry and ability to resolve scales over a reasonably large domain. In the proposed study, two-component particle image velocimetry which collects the velocity field vectors under accurate consideration of refractive index matching is compared statistically and visually with the modeled velocity field emanated from direct numerical simulation to evaluate both methods for consistency. The characteristics of the porous media used in this experiment is controlled by a randomly packed bed using uniformly sized spherical particles. There are many challenges that made this work interesting to be considered as an accurate comparison between computation and experimentation that includes refractive index matching errors, magnification uncertainties, and the uncertainties in identifying of the proper geometry of the beads as well as, the arduousness, of matching the geometry, grid resolution particularly near solid contact points, and proper boundary conditions in DNS. Detailed analogy of different resolutions in numerical simulation with PIV measurements are visualized by attention paid to the statistical distribution of velocities, and the deviations of DNS estimations from the measured values. There is accurate and reasonable matching the velocity fields except for some regions of constricted flow. The axial velocity results are within 6-7 percent (for different DNS resolutions) and the normal velocity within 4-6 %. Streamline details show that both methods are within the good range of agreement. This study is a comprehensive study of matching experiment with numerical results in a very low Reynolds number range for porous media flows.