Fig. 11 Water and hydrocarbon velocity profiles at the
acceleration and water concentration of 0.002 nm/ps2and 71.43% respectively in different P-H nanopore sizes. The result
indicates that pore size impacts the velocity patterns. At 5nm, we
observe a parabolic shape for the flow profiles which get progressively
flatter as the pore size increases.
In Fig. 12, we take a closer look at the water bridges present in the
P-H pores at a water concentration of 71.43%. Hydrocarbon molecules are
not shown for clarity. The red-colored water molecules are those
adjacent to the pore surface and the yellow-colored water molecules are
those present in the water bridge. Fig. 12a shows the distribution of
water in a 5nm P-H pore obtained from our equilibrium MD (EMD
simulations) on top and under an acceleration of 0.002
nm/ps2 on the bottom. It should be noted that the
water bridge in Fig. 12a is a sheet extending across the entire
x-direction in the 5nm P-H nanopore.
Figs. 12b-c show the corresponding information for 10nm and 15nm pore
widths respectively. Water molecules move freely between the water
bridge and adsorbed layer resulting in the velocity profile in Fig. 12a
(shown in a blue line). However, when pore sizes increase to 10 nm or 15
nm, there is limited or no exchange of water molecules between the film
and the bridge. The combination of a constant acceleration and no
exchange contributes to the flat velocity profiles observed in Figs.
12b-c.