Case 4: Flow separation at vertical step
Figure 18(d) shows flow over a vertical step. Flow separation that occurs in
the lee of the step exhibits a dominant vertical turbulence component. Although
this is a less common situation in the real world, the experiments provided an
opportunity to evaluate the scale effect where vertical turbulence generation is
predominant.
Figure 18. Turbulent flow cases tested on flow table
For each different configuration the first test in the series was considered to
be the target or prototype condition representing results from an undistorted
model. Subsequent tests in the series were designed to be increasingly distorted
versions of the target condition. In other words, the follow-up tests were
distorted scale models of the first test.
throughout the area of interest including the turbulent regions created by the flow
disturbance. Measured mean values of the two horizontal components of
velocity at all locations for each of the distorted tests were scaled to the
undistorted target equivalent by applying appropriate length scale factors. These
scaled horizontal velocity vectors were then compared to those obtained for the
target condition. Good correspondence indicated minimal turbulence scale
effect.
Scale relationships
The geometrically scaled versions of each target condition were designed
following established Froude scaling relationships for distorted flow models.
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Chapter 5 Turbulence Scale Effects Experiments
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