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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 paper, a generalized set of pipeline column separation equations is presented describing all conventional types of low-pressure regions, including water hammer zones, distributed vaporous cavitation, vapor cavities, and shocks.
Abstract: A generalized set of pipeline column separation equations is presented describing all conventional types of low-pressure regions. These include water hammer zones, distributed vaporous cavitation, vapor cavities, and shocks (that eliminate distributed vaporous cavitation zones). Numerical methods for solving these equations are then considered, leading to a review of three numerical models of column separation. These include the discrete vapor cavity model, the discrete gas cavity model, and the generalized interface vaporous cavitation model. The generalized interface vaporous cavitation model enables direct tracking of actual column separation phenomena (e.g., discrete cavities, vaporous cavitation zones), and consequently, better insight into the transient event. Numerical results from the three column separation models are compared with results of measurements for a number of flow regimes initiated by a rapid closure of a downstream valve in a sloping pipeline laboratory apparatus. Finally, conclusions are drawn about the accuracy of the modeling approaches. A new classification of column separation (active or passive) is proposed based on whether the maximum pressure in a pipeline following column separation results in a short-duration pressure pulse that exceeds the magnitude of the Joukowsky pressure rise for rapid valve closure.
129 citations
TL;DR: In this paper, an experimental study of asymptotic sink-flow turbulent boundary layers is reported, and three levels of acceleration corresponding to values of the acceleration parameter K of 1·5 × 10−6, 2·5× 10×6, and 3·0 × 10 ×6 have been examined.
Abstract: An experimental study of asymptotic sink-flow turbulent boundary layers is reported. Three levels of acceleration corresponding to values of the acceleration parameter K of 1·5 × 10−6, 2·5 × 10×6 and 3·0 × 10×6 have been examined. In addition to mean velocity profiles, measurements have been obtained of the profiles of longitudinal turbulence intensity, and, for the lowest value of K, of the lateral and transverse components as well. Measurements at selected positions in the boundary layer of the power spectral density indicate that none of the boundary layers exhibit an inertial subrange; for the steepest acceleration, in particular, throughout the boundary layer the spectrum shapes are similar in form to those reported within the viscous sublayer of a high Reynolds number turbulent flow.
129 citations
129 citations
TL;DR: In this paper, the authors proposed a new mechanism about turbulence generation and sustenance, that all small length scales (turbulence) are generated by shear layer instability produced by large vortex structure with multiple level vortex rings, multiple level sweeps and ejections, and multiple level negative and positive spikes near the laminar sub-layers.
129 citations
01 Nov 1976
TL;DR: In this paper, a large variety of two dimensional flows can be accommodated by the program, including boundary layers on a flat plate, flow inside nozzles and diffusers (for a prescribed potential flow distribution), flow over axisymmetric bodies, and developing and fully developed flow inside circular pipes and flat ducts.
Abstract: A large variety of two dimensional flows can be accommodated by the program, including boundary layers on a flat plate, flow inside nozzles and diffusers (for a prescribed potential flow distribution), flow over axisymmetric bodies, and developing and fully developed flow inside circular pipes and flat ducts. The flows may be laminar or turbulent, and provision is made to handle transition.
128 citations