Three-Dimensional Permeability Study of Open Graded Friction Course (OGFC) Based on CFD Simulation

This research evaluated permeability and hydraulic conductivity of Open Graded Friction Course (OGFC) in multiple directions. Using Computational Fluid Dynamics (CFD), Ansys Fluent was utilized to simulate the laminar flow model for twelve cubic specimens of OGFC with different geometry and various porosities. Reynolds number (R_e), permeability (K), and hydraulic conductivity (k) were computed for each simulation horizontally and vertically. According to the study, the horizontal permeability measurements were greater than the vertical measurements. Moreover, the permeability of OGFC is governed by the percentage of the air voids, aggregate particle size, and the thickness of the specimens. As the diameter and percentage of air voids increased, the permeability increased. Specimens with large size of aggregates and larger thicknesses have the highest values of permeability, while specimens with the small size of aggregates have the lowest values of permeability. In addition, the velocity of the flow inside the voids decreased as the diameter and percentage of air voids increased, while the pressure increased, according to the study.