Topic
Flow separation
About: Flow separation is a research topic. Over the lifetime, 16708 publications have been published within this topic receiving 386926 citations.
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TL;DR: In this article, the drag of a non-spherical particle was reviewed and investigated for a variety of shapes (regular and irregular) and particle Reynolds numbers (Rep), and point-force models for the trajectory-averaged drag were discussed for both the Stokes regime (Rep≪-1) and Newton regime(Rep≫-1 and sub-critical with approximately constant drag coefficient) for a particular particle shape.
333 citations
TL;DR: In this article, two independent experimental investigations of the behavior of turbulent boundary layers with increasing Reynolds number were recently completed, and the results are summarized here, utilizing the profiles of the mean velocity, for Reynolds numbers based on the momentum thickness ranging from 2500 to 27,000.
Abstract: Two independent experimental investigations of the behavior of turbulent boundary layers with increasing Reynolds number were recently completed. The experiments were performed in two facilities, the Minimum Turbulence Level (MTL) wind tunnel at Royal Institute of Technology (KTH) and the National Diagnostic Facility (NDF) wind tunnel at Illinois Institute of Technology (IIT). Both experiments utilized oil-film interferometry to obtain an independent measure of the wall-shear stress. A collaborative study by the principals of the two experiments, aimed at understanding the characteristics of the overlap region between the inner and outer parts of the boundary layer, has just been completed. The results are summarized here, utilizing the profiles of the mean velocity, for Reynolds numbers based on the momentum thickness ranging from 2500 to 27 000. Contrary to the conclusions of some earlier publications, careful analysis of the data reveals no significant Reynolds number dependence for the parameters desc...
332 citations
TL;DR: Flow profiles were studied in two successive generations of large scale symmetrical models of typical junctions of the human bronchial tree, suggesting that flow patterns are complex and parabolic flow cannot be assumed.
332 citations
01 Jan 2004
TL;DR: Turbulence model development for aerodynamic applications has for many years concentrated on improving the capabilities of CFD methods for separation prediction as discussed by the authors, which has led to a series of models capable of capturing boundary layer separation in good agreement with experimental data.
Abstract: Turbulence model development for aerodynamic applications has for many years concentrated on improving the capabilities of CFD methods for separation prediction. Validation studies of turbulence models in the ‘80th have clearly shown that most turbulence models were not capable of predicting the development of turbulent boundary layers under adverse pressure gradient conditions. Based on that observation, new models were developed to specifically meet this challenge, resulting in a series of models capable of capturing boundary layer separation in good agreement with experimental data (Johnson and King 1984, Menter 1993, Spalart and Allmaras 1994).
327 citations
TL;DR: It is found that the surface of the edge of chaos coincides with the stable manifold of a periodic orbit, whereas at higher Reynolds numbers it is the stable set of a higher-dimensional chaotic object.
Abstract: We study the transition between laminar and turbulent states in a Galerkin representation of a parallel shear flow, where a stable laminar flow and a transient turbulent flow state coexist. The regions of initial conditions where the lifetimes show strong fluctuations and a sensitive dependence on initial conditions are separated from the ones with a smooth variation of lifetimes by an object in phase space which we call the ``edge of chaos.'' We describe techniques to identify and follow the edge, and our results indicate that the edge is a surface. For low Reynolds numbers we find that the surface coincides with the stable manifold of a periodic orbit, whereas at higher Reynolds numbers it is the stable set of a higher-dimensional chaotic object.
325 citations