Figure 49. Comparison of horizontal flow magnitudes in lee of a vertical step
Horizontal velocities at the elevation of the step show remarkable
correspondence considering this is near the flow separation boundary. Farther
down in the entrainment region, the plots show similar magnitude envelopes, but
the details differ due to the turbulent nature of the flow. Nevertheless, the
comparison was judged to be reasonable. Close to the bottom, the flow is almost
motionless.
Case 4 discussion and conclusions
The vertical step generated flow separation turbulence predominantly in the
vertical plane with only weak horizontal turbulent fluctuations. Consequently,
the turbulence terms in the equations of motion that are not in similitude (i.e.,
terms containing products of the horizontal and vertical fluctuations) are small
relative to the dominant terms. Therefore, turbulent scale effects arising from the
distorted models were very minor, and good similitude was seen throughout the
flow field. Details within the entrainment region exhibited variations in the
average due to the turbulence, but the bounds of the magnitudes were similar.
The flow separation boundary seemed to be well reproduced.
Conclusions from Turbulence Scale Effects
Experiments
An extensive set of experiments was conducted to determine potential
turbulence scale effects that might arise due to flow separation in geometrically
distorted physical models. Four distinct cases were examined: (a) flow
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Chapter 5 Turbulence Scale Effects Experiments
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