The dynamical behavior of the flow separation induced by a wall-mounted two-dimensional bump is studied. The present investigation is based on an experimental approach that aims to provide further insight into the separate flow dynamic in such configuration. The main interest is devoted to the separation Reynolds number dependency. A general feature of separated flows dynamics is also addressed by statistical and structural information derived from the present experimental approach. Results are presented for turbulent water inflow for a moderate Reynolds-number range from 165 to 605 based on friction velocity and channel half-height (so-called Kármań number). The ratio of the bump height h and the channel full height H is 0.335. The unsteady separation process and the associate instability mechanism are very sensitive to small perturbations. So, in order to preserve the flow physics, all of the experimental techniques employed in the present study are non-intrusive. An examination of the high resolved velocity fields showed that for a moderate Kármań number, a separate area exists. Under this condition, a thin region of reverse flow was formed above the bump and a large-scale vortical activity, characterized by low-frequencies, are clearly observed. The reported results do not only yield the expected turbulent separation bubble dependencies. They also show that the well known coexisting instabilities process, which find their origin in laminar flow regime, persist for higher Kármań numbers.
- Fluids Engineering Division
Experimental Characterization of the Separate Flow Induced by a Wall-Mounted Bump
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Fadla, F, Keirsbulck, L, Aloui, F, & Laval, J. "Experimental Characterization of the Separate Flow Induced by a Wall-Mounted Bump." Proceedings of the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels. Volume 1B, Symposia: Fluid Machinery; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Flow Manipulation and Active Control: Theory, Experiments and Implementation; Multiscale Methods for Multiphase Flow; Noninvasive Measurements in Single and Multiphase Flows. Chicago, Illinois, USA. August 3–7, 2014. V01BT14A002. ASME. https://doi.org/10.1115/FEDSM2014-21136
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