A vertically banded structure contains distinct vertical bands of similarly sized pores and throats as shown below. All non-wetting fluids, wetting fluids and gases are applied in the -z direction from the top face, as also shown below, so the layers are parallel to the direction of fluid flow.
The unit cell shown is on a 30x30x30 Cartesian grid of pores, with 5% porosity, and a correlation level of 0.2 - i.e. the throats are not particularly well sorted into layers.
Vertically banded unit cell with 1% porosity and a correlation level of 0.9