50.
Genuine plane Couette flow is hard to realize experimentally, and no applications of modern spatially resolving measurement
techniques have been reported for this flow so far. In order to resolve this shortcoming, we designed and built a new experimental
facility and present our first results here. Our setup enables us to access the flow via 3D particle tracking velocimetry
and therefore to obtain truly three-dimensional flow fields for the first time experimentally in plane Couette flow. Results
are analyzed in terms of basic flow properties, and a clear distinction of flow regimes (laminar for
Re < 320, transitional for 320 <
Re < 400, and turbulent when
Re > 400) could be made. Comparison with DNS data shows good agreement in the turbulent regime and builds trust in our data.
Furthermore, vortical coherent structures are studied in detail with the additional help of kalliroscope imaging, and the
typical vortex spacing is determined to be roughly one gap width. As a noteworthy result, we find that the onset of the turbulent
regime coincides with the range of Reynolds numbers at which a distance of 100 wall units is comparable to the gap width.
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