Part I. An Analysis of Reiner's Centripetal Pump. Part II. A Study of Some Turbulent Flows Using a Model for Inhomogeneous Turbulence
<p>Part I: A centripetal pump consists of a self-aligning rotor in rotation close to a fixed plane stator. In such an apparatus Reiner observed an excess air pressure in the gap between the discs over ambient and a consequent repulsive force between the discs. Reiner interpreted this repulsive...
| Summary: | <p>Part I: A centripetal pump consists of a self-aligning rotor in rotation close to a fixed plane stator. In such an apparatus Reiner observed an excess air pressure in the gap between the discs over ambient and a consequent repulsive force between the discs. Reiner interpreted this repulsive force to be the result of non-Newtonian properties of air. Since this hypothesis is in contradiction with known behavior of air in other similar situations, we try to explain it as due to imperfections of the apparatus used and consider three possibilities: dynamic unbalance of the rotor, instability of the rotor and vibrations of the stator. The results of the analyses show that the third possibility can explain Reiner's observations under some reasonable assumptions. It is concluded that Reiner's hypothesis is unjustified.</p>
<p>Part II: A model for inhomogeneous turbulence, due to Saffman, describes turbulence in terms of two scalar densities governed by nonlinear diffusion equations. Using this model some turbulent flows are studied to assess the value of the model as a basis for analyzing turbulent flows. The specific problems studied include the two-dimensional wake, the two-dimensional jet, the turbulent couette flow, flow in a channel and the turbulent trailing vortex. Predictions based on the model agree fairly well with experimental results except for the turbulent trailing vortex. Some shortcomings of the model as evident from the application are discussed.</p> |
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