Typically, turbulent flow may fall in a range of Reynolds numbers from 1,000 to 100,000 or more, depending on the impeller type. The degree of turbulence determines the size of the eddy currents formed. ![]() Reynolds numbers have been used for many years to delineate the boundary between turbulent flow and stable laminar flow. Turbulence can be further described in terms of a Reynolds number, a dimensionless value computed from the flow velocity, density and viscosity of the fluid. But this type of turbulence is generally irrotational (i.e., lacking in rotation or vorticity). In rare cases where the root-mean-square fluctuating velocities are equal, a condition known as isotropic turbulence exists. This flow is usually described in terms of intensity by measuring the fluctuating velocity relative to the mean velocity. The lower the viscosity, the more turbulent and extended the flow. The face of the rotating blade generates significant motion, both axially and radially, typically to distances of two to 10 blade diameters. When a turbine-type mixer creates turbulence in the lower viscosity ranges (less than 5,000 centipoise), the resulting flow is chaotic. To better understand the ramifications of high-viscosity mixing, let’s first review a much simpler case - that of turbulent flow in low-viscosity mixing. Yet, in the case of mixing highly viscous materials, achieving uniformity is often a difficult, but not impossible, challenge. ![]() One way to view mixing is as a method to cause separate ingredients otherwise independent from one another to interface as a result of an external force. Publications Understanding High Viscosity Mixing
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