Fig. 2.
Diffusion occurs as the result of the Brownian motion of a large number of particles. a Time snapshot of the dispersal of 350 solute particles undergoing one-dimensional (1D) Brownian movement. Particles were initially located along the central plane of the box. The conditions were T = 37°C, η = 1 × 10−4 kgm−1 s−1, particle radii = 5 nm, snapshot time =0.001 s. b Dispersal profile described in terms of the number particle linear density as calculated using Eq. 1a (solid lines) and via stochastic simulation of the individual particles trajectories (dots) using Eq. 1b (circles). For solutions carried out using Eq. 1a, DI was estimated from the theoretical relation given in Eq. 1b. Simulation times were t = 0.001 s (green), t = 0.0001 s (red), and t = 0.00001 s (blue)