Modelling the kinetics of aggregate breakage using improved breakage kernel

Abstract

An improved breakage kernel was developed to describe the kinetics of aggregate breakage induced by fluid shear. The model includes the effects of both the internal bonding forces of an aggregate and the fluid shear stress exerting on the aggregate. The ratio of the two opposite forces regulates the probability of the aggregate breakage. With the improved breakage model and the sectional numerical technique, the breakage dominant process can be well simulated by the change in particle size distribution (PSD). The results show that the fractal dimension plays a significant role in the breakage process. AS the fractal dimension approaches three, the aggregates become more difficult to break. Higher shear intensity, to a great extent, enhances the breakage kinetics. The internal forces are directly related to the bonding strength of the aggregates. Hydrophobic forces increase the floc strength and hence reduce the breakage rate and probability. In addition, two distinct breakage daughter distribution functions, binary and ternary, give eventually almost the same results in PSID after breakage. It appears that the breakage daughter distribution function is less important for the description of the particle fragmentation. © IWA Publishing 2008.