Brownian dynamics simulations for rod-like particles in dilute flowing solution

Brownian simulations for the probability distribution functions (PDF) which describe the average orientations of Brownian macromolecular rod-like particles in the bulk of a flowing liquid, P(θ), have been constructed in two dimensions (2D) and three dimensions. These simulations are constructed for a wide range of the quantity α=γ̇/Drot, which depicts the ratio of the hydrodynamic shear rate to the rotational Brownian diffusion, characterizing the coupling of the stochastic thermal diffusion of the macromolecular particles in their motion in the hydrodynamic flow. The agreement between the 2D results of the Brownian dynamics simulations and the numerical solutions of the Boeder differential equation, who permits to calculate these PDF as a function of macromolecular orientations, has been shown to be true for a wide range of α. Although the simulation results show that the maximum of the rod-like orientation θmax varies strongly with the flow, decreasing monotonically from a high angle (∼45°) for a small α to much smaller angles for α∼104.