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 effects of VGs' size were analyzed from several perspectives, such as trailing-edge height, length, short and long spacing between an adjacent pair of generators, and flow field characteristics were further revealed by the analysis of streamlines and vortices in the wake region.
113 citations
17 Jan 1972
TL;DR: In this paper, a computerized analytical model of a multi-component airfoil in viscous, subsonic flow has been developed, representing attached flow, defines viscous pressure distributions, lift, moments, and local boundary-layer properties on each element of an arbitrarily arranged slotted Airfoil.
Abstract: A computerized analytical model of a multi-component airfoil in viscous, subsonic flow has been developed. The model, representing attached flow, defines viscous pressure distributions, lift, moments, and local boundary-layer properties on each element of an arbitrarily arranged slotted airfoil. The final viscous solution is obtained by an iterative technique for successively combining an inviscid solution with boundary-layer displacement thicknesses. Ordinary boundary-layers include laminar, transition, and turbulent types. A significant feature of the program is an analytical model representing the merging of the upper surface boundary layer with the slot efflux. Typical correlations with experiment are provided and program applications are discussed.
113 citations
TL;DR: In this paper, a cone-shaped turbulent vortex breakdown in noncavitating swirling flows at high Reynolds numbers in a slightly diverging cylindrical tube is reported, in addition to the well-known double-helix, spiral, and nearly axisymmetric or bubble bubble breakdowns.
Abstract: Reported herein is a cone‐shaped turbulent vortex breakdown in noncavitating swirling flows at high Reynolds numbers in a slightly diverging cylindrical tube. The turbulent conical form is in addition to the well‐known double‐helix, spiral, and nearly axisymmetric or ‘‘bubble’’‐type breakdowns.
113 citations
113 citations
TL;DR: In this article, the authors use a formulation which considers two kinds of flow perturbations, namely turbulent fluctuations and some disturbances due to boundary irregularities, and derive a simple expression for the friction coefficient which is subsequently compared with extensive series of measurements in the laboratory for granular beds as well as for rippled surfaces.
Abstract: The forces on the seabed in shallow water under waves influence near-shore transport processes. However, the actual nature of these forces is not yet fully understood. Sleath (1987) simultaneously measured horizontal shear force per unit area and Reynolds stress in oscillating turbulent flow over granular beds with the striking result that maximum Reynolds stress was significantly less than total shear force per unit area of bed. Trying to explain these measurements, we use a formulation which considers two kinds of flow perturbations, namely turbulent fluctuations and some disturbances due to boundary irregularities. The resulting spatially averaged Reynolds equations contain in particular two terms which do not appear in the smooth bed case: the force due to the mean momentum flux for boundary disturbances, here called "form-induced stress," which owes its existence to the vorticity of the disturbed motion, and the force exerted by the roughness elements on the fluid. The "jet regime" as introduced by Gimnez-Curto and Comiero (1993) for steady flow is extended to oscillatory flow. In this regime, pressure drag on roughness elements is the fundamental force acting on the boundary, and form- induced stress due to vorticity generated by flow separation from bed irregularities becomes the leading stress, thus providing an explanation for Sleath's measurements by means of a physical mechanism which was already envisaged by Longuet-Higgins (1981) for two-dimensional rippled beds. A simple expression is derived for the friction coefficient which is subsequently compared with extensive series of measurements in the laboratory for granular beds as well as for rippled surfaces, showing an excellent agreement.
112 citations