Bubble Dynamics and Mass Transfer in Shear Flow

10 BUBBLE DYNAMICS AND MASS TRANSFER IN SHEAR FLOW 

In devolatilizing systems, however, Ca 1 and the bubbles deform into slender S-shaped bodies, as shown in Fig. 8.12. Hinch and Acrivos (35) solved the problem of large droplet deformation in Newtonian fluids. They assumed that the cross section of the drop is circular, of radius a, and showed that the dimensionless bubble surface area, A, defined as the ratio of the surface area of the deformed bubble A to the surface area of a spherical bubble of the same volume, is approximated by (36)  

Canedo et al. (36) confirmed these predictions for bubbles in a Couette flow apparatus. 

Favelukis et al. (37,38) dealt with the problem of droplet deformation in exten-sional flow with both Newtonian and non-Newtonian Power Law model fluids, as wellas bubble breakup. For the Newtonian case, they find that as an inviscid droplet (or bubble) deforms, the dimensionless surface area is proportional to the capillary number 

extensional flow is more efficient in increasing surface area as compared to shear flow. 

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Bubble Dynamics and Mass Transfer in Shear Flow, 430... 

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