Numerical Computation of Vortical Flow Fields of Double-Delta Wings Moving in a Compressible Viscous Medium

1994 ◽  
Vol 74 (10) ◽  
pp. 475-486 ◽  
Author(s):  
A. Das ◽  
J. M. A. Longo
Keyword(s):  
Numerical Computation ◽  
Flow Fields ◽  
Viscous Medium ◽  
Vortical Flow ◽  
Delta Wings

On the Importance of Assumptions for Bulk Flow in Hemodynamic Models of the Carotid Bifurcation

2011 ◽  
Author(s):  
Umberto Morbiducci ◽  
Diana Massai ◽  
Diego Gallo ◽  
Raffaele Ponzini ◽  
Marco A. Deriu ◽  
...  
Keyword(s):  
Vessel Wall ◽  
Carotid Bifurcation ◽  
Flow Fields ◽  
Transport Processes ◽  
Bulk Flow ◽  
Arterial System ◽  
Vortical Flow ◽  
Primary Role ◽  
4D Flow ◽  
The Impact

It is widely accepted that the local hemodynamics in the arterial system affects the atherogenic process. In particular the hemodynamic environment at the carotid artery bifurcation has been widely studied due to its predilection for atherosclerosis. Much effort has been spent in the past on image-based CFD carotid bifurcation models to assess the sensitivity to several assumptions of wall shear stress (WSS)-based parameters as indicators of abnormal flow. This luminal-surface-oriented approach was historically driven by histological observations on samples of the vessel wall. The consequence for this was that the reduction of the complexity of 4D flow fields focused mainly on WSS. However, few studies have provided adequate insights into the influence of these assumptions in order to confidently model the 4D hemodynamics within the bifurcation. Only recently the interest in the role played by the bulk flow in the development of the arterial disease has grown dramatically. This is the consequence of the emerging awareness that arterial hemodynamics, being an intricate process that involves interaction, reconnection and continuous re-organization of structures, could play a primary role in the regulation of mass transfer, and of its athero-protective/susceptible effect. Earlier works [1] pointed out the existence of a relationship between helical/vortical flow patterns and transport processes that could affect blood-vessel wall interaction, and might cause alterations in the residence time of atherogenic particles involved in the initiation of inflammatory response. Recently we introduced robust quantitative descriptors of bulk flow that can “reduce” the inherent complexity associated with 4D flow fields in arteries [1]. Here we present a study on the impact of assumptions on blood rheology and outflow boundary conditions (BCs) on bulk flow features within healthy carotid bifurcations, by using 4D flow descriptors. The final goal is to provide adequate insights not only to complement and to integrate, but also to extend with a quantitative characterization of the bulk flow the description currently adopted to classify altered hemodynamics.

705 Numerical Analysis of Complex Vortical Flow Phenomena in Transonic Internal Flow Fields

2001 ◽  
Vol 2001 (0) ◽  
pp. 97
Author(s):  
Masato FURUKAWA ◽  
Kazutoyo YAMADA ◽  
Aritoshi IMAZATO ◽  
Masahiro INOUE
Keyword(s):  
Numerical Analysis ◽  
Internal Flow ◽  
Flow Fields ◽  
Vortical Flow ◽  
Flow Phenomena

Prediction of tunnel wall upwash for delta wings including vortex breakdown effects

1999 ◽  
Vol 103 (1021) ◽  
pp. 139-142 ◽  
Author(s):  
L. W. Traub
Keyword(s):  
Vortex Breakdown ◽  
Side Wall ◽  
Vortical Flow ◽  
Navier Stokes ◽  
Wall Effects ◽  
Integral Expression ◽  
Image System ◽  
Tunnel Wall ◽  
Delta Wings ◽  
Side Walls

AbstractAn incompressible method is presented to predict the upwash corrections associated with vortical flow as a result of wind-tunnel side wall effects. An image system is used to simulate the tunnel side walls which are assumed to be solid. An integral expression is formulated, representing the average upwash induced over the wing by the image system. Wall effects may be determined for flows with and without vortex breakdown. Comparisons of the results with upwash predictions from a Navier-Stokes study show close accord. The upwash expression also displayed the ability to successfully predict corrections for flows involving vortex breakdown.

Recent developments in delta wing aerodynamics

2004 ◽  
Vol 108 (1087) ◽  
pp. 437-452 ◽  
Author(s):  
I. Gursul
Keyword(s):  
Shear Layer ◽  
Vortex Breakdown ◽  
Delta Wing ◽  
Layer Structure ◽  
Vortical Flow ◽  
Time Lags ◽  
Delta Wings ◽  
Vortex Interactions ◽  
Recent Developments ◽  
Wing Aerodynamics

Abstract Recent developments in delta wing aerodynamics are reviewed. For slender delta wings, recent investigations shed more light on the unsteady aspects of shear-layer structure, vortex core, breakdown and its instabilities. For nonslender delta wings, substantial differences in the structure of vortical flow and breakdown may exist. Vortex interactions are generic to both slender and nonslender wings. Various unsteady flow phenomena may cause buffeting of wings and fins, however, vortex breakdown, vortex shedding, and shear layer reattachment are the most dominant sources. Dynamic response of vortex breakdown over delta wings in unsteady flows can be characterised by large time lags and hysteresis, whose physical mechanisms need further studies. Unusual flow–structure interactions for nonslender wings in the form of self-excited roll oscillations have been observed. Recent experiments showed that substantial lift enhancement is possible on a flexible delta wing.

Control of High-Incidence Vortical Flow on Double-Delta Wings Undergoing Sideslip

1997 ◽  
Vol 34 (4) ◽  
pp. 506-513 ◽  
Author(s):  
Sheshagiri K. Hebbar ◽  
Max F. Platzer ◽  
Wen-Huan Chang
Keyword(s):  
Vortical Flow ◽  
Delta Wings ◽  
High Incidence
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