Fractal dimensions of aggregates from shear devices

If more accurate estimates of coagulation kinetics are to be derived, future derivation of coagulation kernels must rely on incoporation of fractal dimensions into collision kernels. Average fractal dimensions of aggregates of fluorescent microspheres were measured as a function of mean shear rate and ionic strength using a new technique that relies on simultaneous measurement of size spectra in terms of aggregate length and solid volume. To demonstrate that changes in ionic strength produced changes in particle stickiness, the authors determined that collision efficiencies of a monodisperse suspension varied between 0.0016 and 0.37 when NaCl concentrations ranged from 0.05 to 0.8 M. Average fractal dimensions of D 1 = 1.11, D 2 = 1.85, and D 3 = 1.81, measured for aggregates produced under turbulent shear conditions using paddle mixers, were not a function of NaCl concentration.