Print Email Facebook Twitter Turbulence characteristics in sharp open-channel bends Title Turbulence characteristics in sharp open-channel bends Author Blanckaert, K. De Vriend, H.J. Faculty Civil Engineering and Geosciences Department Hydraulic Engineering Date 2005-04-11 Abstract In spite of its importance, little is known about the turbulence characteristics in open-channel bends. This paper reports on an experimental investigation of turbulence in one cross section of an open-channel bend. Typical flow features are a bicellular pattern of cross-stream circulation (secondary flow) and a turbulence activity in the outer bend that is significantly less than in the equivalent straight uniform shear flow. Measured distributions are given of the turbulent kinetic energy, its production, the mixing coefficients, some parameters characterizing the turbulence structure, and the fourth-order correlations of the turbulent velocity fluctuations. The transport equation for the turbulent kinetic energy is evaluated term by term, on the basis of the measured data. The results show that the turbulence structure is different from straight uniform flow, in that the Reynolds stress tensor is more diagonally dominant. This is shown to be the main cause of the observed reduction of turbulence activity in the outer bend. The usual two-equation turbulence closure models include a transport equation for the turbulent kinetic energy, but they do not account for this modified turbulence structure. The departures of the measured turbulence structure from its equivalent in straight uniform shear flow are related to a curvature-flux-Richardson number Rf which includes the streamline curvature. Such a relation may be useful to improve simple turbulence closure models for curved open-channel flow. Subject shear turbulencechannel flowflow instabilityflow simulationpattern formationfluctuationsmixing To reference this document use: http://resolver.tudelft.nl/uuid:4555be50-6448-4fe6-85b1-0cac7c261c15 DOI https://doi.org/10.1063/1.1886726 Publisher American Institute of Physics ISSN 1070-6631 Source http://link.aip.org/link/PHFLE6/v17/i5/p055102/s1 Source Physics of Fluids, 17 (5), 2005 Part of collection Institutional Repository Document type journal article Rights (c) 2005 The Author(s); American Institute of Physics Files PDF deVriend_2005.pdf 2.55 MB Close viewer /islandora/object/uuid:4555be50-6448-4fe6-85b1-0cac7c261c15/datastream/OBJ/view