Rotating cylinder properties

Considering an incompressible fluid with constant properties (Eq. 3.81), the equations governing the circumferential incompressible flow profile between rotating cylinders reduce to ... 

Rotational Viscometers. Rotational viscometers are the most widely used instruments for the measurement of the rheological properties of a fluid (e.g., a pure liquid, emulsion, or suspension). The test fluid is placed in a gap formed by either two coaxial rotating cylinders, two flat discs, or a flat disc and a cone. The major advantages of the rotational viscometers are... 

So far, the general point of departure for the nonlinear analyses attempted has been not the set of equations of motion in their complete form, but rather the set that results by neglecting the temperature dependence of all fluid properties except density, and also the dissipation of kinetic energy. This is known as the Boussinesq approximation. Using the Boussinesq equations, Woronetz (Wl) was able in 1934 to obtain expressions for the velocity perturbations in a fluid confined between coaxial rotating cylinders or spheres which were maintained at different temperatures. Volkovisky (V3) used the... 

The flow-property or rheological constants of non-Newtonian fluids can be measured using pipe flow as discussed in Section 3.5E. Another, more important method for measuring flow properties is by use of a rotating concentric-cylinder viscometer. This was first described by Couette in 1890. In this device a concentric rotating cylinder (spindle) spins at a constant rotational speed inside another cylinder. Generally, there is a very small gap between the walls. This annulus is filled with the fluid. The torque needed to maintain this constant rotation rate of the inner spindle is measured by a torsion wire from which the spindle is suspended. A typical commercial instrument of this type is the Brookfield viscometer. Some types rotate the outer cylinder. 

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