Microscopic Darcy flux with the Macroscopic Darcy's law:
How exactly do we bridge the gap between these two different scales?
The Darcy flux (or the apparent velocity) pertains to the microscopic-scale scenario, while the Darcy's law pertains to the macroscopic scale.
The apparent velocity at the microscopic-scale can be converted into an equivalent actual velocity of fluid pertaining to the macroscopic-scale by dividing the apparent velocity with the effective porosity.