Deformation during drop formation

However, drop formation is not the only situation during which a new surface is created. Indeed, while the volume of fluid inside a drop must be ccmserved, its shape may vary and with it the surface area of its interface. For instance, a spherical drop (of minimal surface area) may be deformed by the external flow to form an oval or other shape. This creation of a new surface is coupled with the presenc e of Marangoni stresses as we shall see below, the surfac e variaticMi can create Marangoni stresses, but it can also be caused by uneven distribution of surfactant. 

In the case when both the droplets and the suspending medium are viscoelastic liquids, Wu (1987) reported that drops can break up during extmsion even when A > 4. However, owing to the complex nature of the deformation during flow through an extruder, it was difficult to even speculate on the origin of this phenomenon. Van Oene (1978) studied the mechanisms of two-phase formation in a mixture of two viscoelastic fluids. He pointed out that, besides the viscosity ratio and the equilibrium interfacial tension of the two liquids, the elasticity of the liquids plays an important... 

Lin B, Sundararaj U. Sheet formation during drop deformation and breakup in polyethylene/polycarbonate systems sheared between parallel plates. Polymer 2004 45(22) 7605-7613. 

Emulsions are commonly produced at well-eads during primary and secondary (waterflood) oil production. For these processes the emulsification is usually not attributed to formation in reservoirs, but rather to formation in, or at the face of, the well-ore itself [693]. However, at least in the case of heavy-il production, laboratory [694] and field [695,696] results suggest that water-in-oil emulsions can be formed in the reservoir itself during water and steamflooding. Energy is needed for emulsification, partly because of the increased surface area that is created in forming small droplets and partly because deformation of large drops is needed before smaller... 

Chou, W.-H., L.-P. Hsiang, and G. M. Faeth. 1997. Dynamics of drop deformation and formation during secondary breakup in the bag breakup regime. AIAA Paper No. 97-0797. 

During bag breakup, separation of the flow around the deformed drop leads to a positive pressure difference between the leading stagnation point and the wake. This tends to blow the center of the drop downstream resulting in the formation of the bag [12]. The outer edge forms a toroidal ring to which the bag is attached. 

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