Abstract

TORO-MENDOZA, J; URBINA-VILLALBA, G  and  GARCIA-SUCRE, M. Efecto de la interacción hidrodinámica en la velocidad de floculación de partículas brownianas. Rev. mex. fis. [online]. 2006, vol.52, suppl.3, pp.72-75. ISSN 0035-001X.

The effect of the fluid on the movement of suspended Brownian particles is shown. In order to study the flocculation rate of a suspension, Ermak and McCammon's algorithm [J. Chem. Phys. 69 (1978) 1352] is used to simulate systems containing a fixed initial number of particles but different volume fractions. Commonly, Brownian dynamics algorithms introduce hydrodynamic interactions (HI) through two-body diffusion tensors. These formulations are highly demanding in computer time and fail in dense systems due to an overestimation of HI. In this work, an effective diffusion constant is used. It is evaluated at each time from the local volume fraction of particles and an exact formulae valid at short inter particle distances [Phys. Rev. E 68 (2003) 061408]. For very dilute concentrations, our results are in good agreement with those for tensorial formulations, correcting the anomalous coalescence at higher concentrations. This procedure allows an adecuate evaluation of flocculation rates in dense systems.

Keywords : Flocculation; hydrodynamic interactions; Brownian dynamics; suspensions; emulsions.