Mixing induced coalescence

Separation of the mixed phases is accomplished by gravity settling or less commonly by centrifugation. It can be enhanced by inducing coalescence with packing or electrically, or by shortening the distance of fall to a coalesced phase. Figures 14.11(d), 18.2, and 18.3 are some examples. Chapter 18 deals with some aspects of the separation of liquid phases. 

Fig. 11.37 Suppression of shear flow-induced coalescence by incorporating a very low concentration of SIS triblock compatibilizer into the equiviscous Blend 2. [Reprinted by permission from the Proceedings of the Tenth Semi-annual Meeting of the Polymer Mixing Study, Polymer Processing Institute, Hoboken, NJ (1995).]...

Meijs and Mitchell (13) examined the possibilities of inducing coalescence by gentle turbulent mixing in tube flow, and found that droplets with an initial = 20 pm were coalesced to = 250 pm, by applying a turbulent mix-... 

The interfacial instability of the copolymer was also noticed in the reactively compatibilized Nylon 6/EPM/EPM-g-MA blends [59]. Prolonged mixing at a temperature of 250 °C in the mini-extruder led to shear induced coalescence of the dispersed EPM rubber particles giving rise to coarser domains (see Fig. 3.11). 

As a result of the mechanical action of mixing tools, turbulent or high intensity mixers do create fast moving, aerated, particulate matter systems. Therefore, interparticle collision and coalescence take place in a very similar fashion to that in suspended solids agglomerators. The main difference between the two methods is that in mixers particle movement is caused by mechanical forces while in suspended solids agglomerators drag forces induced by a flow of gas are the principal reason for movement of the bed of particulate matter, coalescence of particles, and agglomeration. 

However, the effect of a small perturbation in action-action-angle type flows is quite different. The two-parameter family of invariant cycles coalesce into invariant tori that are connected by resonant sheets defined by the u(h,l2) = 0 condition. The consequence of this is that contrary to action-angle-angle flows in this case a trajectory can cover the whole phase space and no transport barriers exist. Thus, in this type of flows global uniform mixing can be achieved for arbitrarily small perturbations. This type of resonance induced dispersion has been demonstrated numerically in a low-Reynolds number Couette flow between two rotating spheres by Cartwright et al. 

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