Mixing laminar

mixing in liquids is achieved by several mech iisms which gradually reduce the size or scale of the fluid elements and then redistiibute them in the bulk. If there are initially differences in eoncenttation of a solublematerial, uniformity is gradually achieved, and molecular diffusion becomes progressively more important as the element 

Laminar mixing is achieved by subjecting the polymer to permanent deformation involving shear, squeeze or elongational flow. In the melt-state, imposition of large strains is accompanied by an increase in the interfacial area between material and system. Laminar mixing is influenced strongly by the initial orientation and location of interfacial elements or additives [3]. 

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Turbulent flow, by means of the chaotic eddy motion associated with velocity fluctuation, is conducive to rapid mixing and, therefore, is the preferred flow regime for mixing. Laminar mixing is carried out when high viscosity makes turbulent flow impractical. 

Burners can be designed to produce a luminous flame by means of laminar mixing and partial cracking of the... 

Heywixh). N. I.. Viney, L. J., and Stewart, 1. W. Inst. Chem. Eng. Symposium Series No. 89. Fluid Mixing ]] (1984) 147. Mixing efficiencies and energy requirements of various motionless mixer designs for laminar mixing applications. 

P. N. Kioni, B. Rogg, K. N. C. Bray, and A. Linan, Flame spread in laminar mixing layers The triple flame. Combust. Flame 95 276-290,1993. 

Hessel, V., Hardt, S Lowe, H., ScHONEELD, F., Laminar mixing in different interdigital micromixers - Part I Experimental characterization, AIChE... 

Ottino, J. M. and Chella, R., Laminar Mixing of Poiymeric Liquids A Brief Review and Recent Theoretical Developments, Polym. Eng. Set, 35, 1766 (1995)... 

We can generally state that if a liquid-liquid system is to be mixed by a laminar mixing mechanism, permanent deformation or strain must be imposed on the system (6). The term... 

Fig. 7.3 Laminar mixing in laminar pipe flow. Dark areas are occupied by a tracer consisting of the bulk liquid and a small amount of a dye.

In the following two examples we show the quantitative relationship between shear strain and interfacial area and the effect of orientation in laminar mixing. 

The scale in chaotic laminar mixing goes down from the machine scale to a scale where the continuum hypothesis breaks down and phenomena are dominated by physical effects, due to intermolecular forces, such as van der Waals. Danescu and Zumbrunnen (21) and Zumbrunnen and Chibber (22) took advantage of this and devised an ingenious device to create controlled three-dimensional chaotic flows, with which they were able to tailor the morphology and properties of blend films and composites. 

However, predictions from simple flows, such as those described in Example 7.3 above, cannot be generalized to more realistic systems. Bigg and Middleman (23) analyzed a somewhat more realistic system of flow in a rectangular channel, shown in Fig. 7.15. The motion of the upper surface induces partial mixing of the fluids, and the interfacial area, which was calculated as a function of time, is used as a quantitative measure of the laminar mixing. The marker and cell calculation method, developed by Harlow and Welch (24), was used to solve the flow field and calculate the position of the interface. The evolution of the interface of two fluids of equal viscosities and densities in a channel with an aspect ratio of 0.52, and a... 

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