In situ measurement of particle aggregation and breakage kinetics in a concentrated suspension

Fractal Dimension of Cohesive Sediment Flocs at Steady State under Seven Shear Flow Conditions

“…This median size vs. time behavior depicts the flocculation process of type II, which is also composed of the three following phases: fast floc growth (referred to as type II-phase 1 herein), breakage and restructuring (type II-phase 2), and a steady state (type II-phase 3), as described in Section 1 of this paper. The type II-phase 1 presented in the figure could be approximately described as a simple linear increase process, as shown in several previous studies [9,11,20,21,55], rather than the exponential process reported by many authors [10,18,20,56]. Ehrl et al [17] attributed the difference between the linear and exponential trends of the fast aggregate growth phase to different particle sizes for which the relative importance of Brownian motion and shear-induced aggregations changed correspondingly [9].…”

“…This type of size-time profile is henceforth referred to as type I. However, the profile is referred to as type II when the median size initially increases to a maximum value with time and then decreases again before reaching a steady state [9,11,[19][20][21][22][23][24]. This peak in the size-time curve during the aggregation process potentially occurs as a result of breakups and/or restructurings (breakages and re-aggregations) of the flocs according to recent studies conducted by Bubakova et al and Selomulya et al [9,22].…”

Turbulent Aggregation of Titania in Water

“…Experimentally, turbidity decreases smoothly with time whereas the simulated time-turbidity curves present a strong bend just before the steady state: from this point on, competition between aggregation and fragmentation suddenly appears. In fact, the usual fragmentation kernels are suitable for describing the breakage behavior of aggregates which have "forgotten" the conditions of their formation, i.e., after restructuring (59)(60)(61)(62). When an aggregate is newly formed by the collision of two smaller aggregates and has no time for restructuring, the local flow shear can disrupt it into its original two components.…”

Polymer flocculation of calcite: Relating the aggregate size to the settling rate

“…Figures 2, 3, 4, and 5 show a slight reduction in aggregate size on extended shearing, typical of aggregates formed by polymer flocculants. 10,[67][68][69] This effect could be interpreted as either aggregate compaction, or partially irreversible breakage (or both). 57,64,70 However, aggregate breakage appears to be the dominant mechanism for this system, because in all cases the hindered settling velocities also drop with aggregate size on extended shearing.…”