Macro level mixing - Physical processing
Fluid Motion Mixing is about the description of fluid
flow generated by an impeller. Macro-level mixing topics
covered here are flow patterns
, velocity profiles, velocity gradients,
shear rates and distribution, turbulence spectrum,
energy dissipation, pressure gradients, and
impeller power consumption. Methodologies to measure these
are also discussed. Many of these characteristics change with the
flow regime, so the discussion of the effects of laminar,
transitional, and turbulent flow regimes also belongs here. Obviously, the Reynolds-number, Re, is a main parameter that describes
these changes. Since Re is a function of viscosity, the discussion
of the viscous properties of the fluids and slurries are
also discussed here and how they affect mixing. Many
other dimensionless numbers are mentioned here, too, such as the
power number, Np, the flow number, Nq, and the head number, Nh.
You could call this area - Basic Mixing Principals. Some processes
are designed merely on the basis of its pumping capacity, its
flow pattern, or the degree of
shear produced.
Without baffles,
most impellers styles impose a tangential flow pattern. With
baffles, most impellers
show their true flow characteristics.
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