scholarly journals Numerical Simulations of the Transient Flow Response of a 3D, Low-Aspect-Ratio Wing to Pulsed Actuation

2011 ◽  
Author(s):  
Guillaume Brès ◽  
Ehab Fares ◽  
David Williams ◽  
Tim Colonius
Keyword(s):  
Aspect Ratio ◽  
Numerical Simulations ◽  
Transient Flow ◽  
Low Aspect Ratio ◽  
Flow Response

Experimental Study of Very Low Aspect Ratio Wings in Slender Bodies

2012 ◽  
Author(s):  
M. A. Arevalo-Campillos ◽  
S. Tuling ◽  
L. Parras ◽  
C. del Pino ◽  
L. Dala
Keyword(s):  
Experimental Study ◽  
Aspect Ratio ◽  
Numerical Simulations ◽  
Water Channel ◽  
Vortex Sheet ◽  
The Body ◽  
Low Aspect Ratio ◽  
Moderate Reynolds Number ◽  
Slender Bodies ◽  
Low Aspect Ratio Wings

The dynamics of very low aspect ratio wings (or strakes) vortices in slender bodies are complex due to the interaction of the shed vortex sheet and the body vortex. For missiles at supersonic speeds these interactions are not easily predicted using engineering level tools. To shed some new light onto this problem, an experimental study in a water channel for moderate Reynolds number (Re = 1000) was performed for a 19D body and strake configuration with strakes having a span to body diameter ratio of 1.25. Comparisons to numerical simulations in supersonic flow are also performed. Flow visualisation has been carried out to characterize the vortex dynamics at different angles of attack; these being 11°, 16°, 22° and 27°. The comparison between a slender body without strakes and the body-strake configuration has given some key indicators in relation to the vortex position of the core. Furthermore, unsteady wing-body interference has been observed at angles of attack above 20° for both experimental and numerical simulations. Consequently, the average position of the vortex core is located at larger distances from the missile in comparison to the body without strakes. The numerical simulations show good correlation with the experimental tests even though the dynamic convective interactions between the body vortex and strake vortex sheet are not predicted.

scholarly journals The effect of aspect ratio on adhesion and stiffness for soft elastic fibres

2011 ◽  
Vol 8 (61) ◽  
pp. 1166-1175 ◽  
Author(s):  
Burak Aksak ◽  
Chung-Yuen Hui ◽  
Metin Sitti
Keyword(s):  
Numerical Analysis ◽  
Aspect Ratio ◽  
Numerical Simulations ◽  
Adhesive Strength ◽  
Polyurethane Elastomer ◽  
Rigid Surface ◽  
Elastic Fibres ◽  
Low Aspect Ratio ◽  
Adhesive Interface

The effect of aspect ratio on the pull-off stress and stiffness of soft elastic fibres is studied using elasticity and numerical analysis. The adhesive interface between a soft fibre and a smooth rigid surface is modelled using the Dugdale–Barenblatt model. Numerical simulations show that, while pull-off stress increases with decreasing aspect ratio, fibres get stiffer. Also, for sufficiently low aspect ratio fibres, failure occurs via the growth of internal cracks and pull-off stress approaches the intrinsic adhesive strength. Experiments carried out with various aspect ratio polyurethane elastomer fibres are consistent with the numerical simulations.

MRI investigation and complementary numerical simulations of flow-through random bead packings with low aspect ratio

2005 ◽  
Vol 23 (2) ◽  
pp. 369-370 ◽  
Author(s):  
Claudia Heinen ◽  
Joachim Tillich ◽  
Hans Buggisch ◽  
Thomas Zeiser ◽  
Hannsjörg Freund
Keyword(s):  
Aspect Ratio ◽  
Numerical Simulations ◽  
Low Aspect Ratio ◽  
Flow Through

On the Existence of an Oscillatory Approach to Steady Natural Convection in Cavities

1984 ◽  
Vol 106 (1) ◽  
pp. 104-108 ◽  
Author(s):  
J. C. Patterson
Keyword(s):  
Steady State ◽  
Natural Convection ◽  
Aspect Ratio ◽  
Transient Flow ◽  
Wave Activity ◽  
Scaling Analysis ◽  
Transient Phase ◽  
Low Aspect Ratio ◽  
Approach To Steady State ◽  
Rayleigh Numbers

The recent paper by Patterson and Imberger [1], which analysed the transient phase of natural convection in low aspect ratio cavities, gave a criterion for the presence of an oscillatory approach to steady state in such flows. However, the experiments of Yewell et al. [3] displayed no evidence of this oscillatory approach, even though the criterion was apparently satisfied. In this paper, it is shown that since the flow regimes are described by a series of critical Rayleigh numbers, the ordering of which changes with changing aspect ratio, a criterion for the existence of transient internal waves, valid for all orderings, may be established. Further, the results of [1] are extended by means of flow descriptions valid for two additional orderings. Consequently, it is shown that the experiments addressed a transient flow regime in which internal wave activity would not be expected and that the experimental results are in support of the scaling analysis of [1].

Development of an Ion Beam Probe System for Potential Measurement in the Low Aspect-Ratio Torus Experiment Device

2012 ◽  
Vol 132 (7) ◽  
pp. 567-573
Author(s):  
Hitoshi Tanaka ◽  
Shota Omi ◽  
Jun Katsuma ◽  
Yurie Yamamoto ◽  
Masaki Uchida ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Ion Beam ◽  
Potential Measurement ◽  
Low Aspect Ratio ◽  
Probe System ◽  
Experiment Device
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