Browsing by Author "Cristini, V."

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    Effect of inertia on drop breakup under shear
    Renardy, Yuriko Y.; Cristini, V. (American Institute of Physics, 2001-01)
    A spherical drop, placed in a second liquid of the same density and viscosity, is subjected to shear between parallel walls. The subsequent flow is investigated numerically with a volume-of-fluid continuous-surface-force algorithm. Inertially driven breakup is examined. The critical Reynolds numbers are examined for capillary numbers in the range where the drop does not break up in Stokes flow. It is found that the effect of inertia is to rotate the drop toward the vertical direction, with a mechanism analogous to aerodynamic lift, and the drop then experiences higher shear, which pulls the drop apart horizontally. The balance of inertial stress with capillary stress shows that the critical Reynolds number scales inversely proportional to the capillary number, and this is confirmed with full numerical simulations. Drops exhibit self-similar damped oscillations towards equilibrium analogous to a one-dimensional mass-spring system. The stationary drop configurations near critical conditions approach an inviscid limit, independent of the microphysical flow- and fluid-parameters.
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    Inertia-induced breakup of highly viscous drops subjected to simple shear
    Khismatullin, D. B.; Renardy, Yuriko Y.; Cristini, V. (AIP Publishing, 2003-05)
    We investigate the inertia-driven breakup of viscous drops suspended in a less viscous liquid under simple shear. For Stokes flow, it is known that there is a critical value of the viscosity ratio, beyond which breakup does not occur. We find that for viscosity ratios larger than this, inertia can be used as a mechanism of breakup. Inertia increases the angle of tilt of the drops and effectively leads to emulsification for a wider range of viscosity ratios than in Stokes flow. (C) 2003 American Institute of Physics.
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    Scalings for fragments produced from drop breakup in shear flow with inertia
    Renardy, Yuriko Y.; Cristini, V. (American Institute of Physics, 2001-08)
    When a drop is sheared in a matrix liquid, the largest daughter drops are produced by elongative end pinching. The daughter drop size is found to scale with the critical drop size that would occur under the same flow conditions and fluid properties. Daughter drop volumes saturate to just below 60% of the critical volume as the mother drop size increases. For large Reynolds number, the daughter drop radius scales with the -1/3 case power of the capillary number when the Reynolds number is fixed.