Motion of bubbles and drops
The drag force acting on a gas bubble or liquid droplet will not, in general, be
the same as that acting on a rigid particle of the same shape and size because
circulating patterns are set up inside bubbles and drops. While the radial
essvelocity at the interface is zero, the angular velocity, shear, and normal stres
are continuous across the interface for fluid particles and the velocity gradient
in the continuous phase (hence shear stress and drag force) is therefore less
than that for a rigid particle. In the absence of surface tension and inertial
effects (Reynolds number 1), the terminal velocity of a fluid sphere falling
in an incompressible Newtonian fluid, as calculated from the Stokes’ law
(equation 5.11 with n D 1, X D 1) is increased by a factor Q1 which accounts
:for the internal circulation
5.5 Flow of a liquid through beds of particles
The problems discussed so far relate to the motion of single particles and
assemblies of particles in stationary non-Newtonian media. Consideration will
now be given to the flow of non-Newtonian liquids through a bed of particles,
as encountered in a variety of processing applications. For instance, the
filtration of polymer melts, slurries and sewage sludges using packed beds, or
the leaching of uranium from a dilute slurry of ore in a fluidised bed. Further
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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