Nonlinear Flow through a Packed-Column Experiment

In order to investigate the behavior of flow through granular materials, a packed column test was employed. The laboratory model consisted of a permeameter having 0.2 m diameter and 1 m length. Two kinds of crushed and rounded gravel particles with six different sizes were used as porous materials. By using flow velocity-hydraulic gradient relationships, it was observed that the relationships between velocity and hydraulic gradient are nonlinear and why it is called non-Darcy flow. Evaluating the results of this research for both kinds of aggregates by means of statistical indicators and comparison of different relationships showed the best empirical equation. The relation between Reynolds number and diameter of materials indicated that the friction factor for higher Reynolds numbers decreased and reached to a constant value for both kinds of materials. (C) 2015 American Society of Civil Engineers.