Wobble feet

Large drops (De =1 cm) of chlorobenzene will fall through water with a somewhat erratic oscillatory motion (L3). The drop pitches and rolls. The flight is not vertical but is erratically helical in nature. A series of oscillations, accompanied by waves moving over the interface, can cause the drop to drift several inches in a horizontal direction in a range of a foot or two of fall. Such drops can not oscillate violently as described above, due to the damping action of such movement by the sliding side-wise motion of the wobble. Motion pictures indicate that internal circulation is also considerably damped out by this type of oscillation. Rate of... 

As an example, let us consider the case of mayonnaise which, when placed in a jar, looks like a solid. If the jar is tilted, it does not flow. If the jar is hit softly, the mayonnaise hardly wobbles. Yet anyone can dig a hole with a spocm and spreading with a knife is even easier. Another example of non-Newtonian fluid is beach sand. Hardening of the sand may be clearly perceived under the pressure of a foot, whirdi hist sinks a few millimeters with relative ease. 

Prefer static mixers to intensify (H). For systems where the viscosity increases with time (e.g. polymer reactors) prefer turbines to propellers because turbines are power self-limiting. Check shaft wobble to ensure that impeller will not hit vessel walls if turned on in an empty tank. Consider a foot bearing. 

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