scholarly journals Radius of influence of a vortex

MAUSAM ◽  
2021 ◽  
Vol 49 (4) ◽  
pp. 439-442
Author(s):  
O. P. SINGH
Keyword(s):  
Tropical Cyclone ◽  
Vortex Tube ◽  
Pressure Profile ◽  
Simple Relation ◽  
Wall Region ◽  
Radius Of Influence

Using the pressure profile in and around a vortex tube a simple relation for the radius of influence of the vortex has been derived. The results have been applied to assess the region of maximum devastation in a tornado. The analysis reveals that the occurrence of 'eye wall' region in a tropical cyclone is a hydrodynamical phenomenon.

Influence of the amplitude of a solid wavy wall on a turbulent flow. Part 1. Non-separated flows

1977 ◽  
Vol 82 (1) ◽  
pp. 29-51 ◽  
Author(s):  
Daniel P. Zilker ◽  
Gerald W. Cook ◽  
Thomas J. Hanratty
Keyword(s):  
Shear Stress ◽  
Turbulent Flow ◽  
Fluid Velocity ◽  
Separated Flow ◽  
Pressure Profile ◽  
Leeward Side ◽  
Stress Profile ◽  
Wall Region ◽  
Nonlinear Behaviour ◽  
Wavy Wall

Measurements of the shear-stress variation along and the velocity profiles above a solid wavy wall bounding a turbulent flow are presented for waves with height-to-length ratios of 2a/λ = 0·0312 and 0·05. These are compared with previous measurements of the wall shear stress reported by Thorsness (1975) and by Morrisroe (1970) for 2a/λ = 0·012. The investigation covered a range of conditions from those for which a linear behaviour is observed to those for which a separated flow is just being initiated.Pressure measurements indicate a linear response in that the spatial variation is described quite well by a single harmonic with a wavelength equal to that of the surface. However, the variation of τw for waves with 2a/λ = 0·0312 and 0·05 can be more rapid on the leeward side of the wave. The degree of departure from a sinusoidal variation increases with increasing wave height and fluid velocity and, from the results reported in this paper, it is suggested that nonlinear behaviour will become evident when au*/v [ges ] 27.Many aspects of the flow for all three waves are described by a solution of the linear momentum equations previously presented by Thorsness (1975) and by Thorsness & Hanratty (1977). These include the phase and amplitude of the pressure profile and the first harmonic of the shear-stress profile and the velocity field outside the viscous wall region.These results suggest that up to separation the flow is approximated quite well by linear theory. Nonlinearities affect the flow only in a region very close to the wave surface and are manifested by the appearance of higher harmonics in the variation of τw.

The Effect of Dipyridamole and RA 233 on Human Platelet Function in Vitro

1973 ◽  
Vol 29 (03) ◽  
pp. 694-700 ◽  
Author(s):  
Paul L. Rifkin ◽  
Marjorie B. Zucker
Keyword(s):  
Mechanism Of Action ◽  
Human Blood ◽  
Glass Bead ◽  
Heart Valves ◽  
Human Platelet ◽  
Drug Effects ◽  
Simple Relation ◽  
Prosthetic Heart Valves ◽  
Induced Aggregation

SummaryDipyridamole (Persantin) is reported to prolong platelet survival and inhibit embolism in patients with prosthetic heart valves, but its mechanism of action is unknown. Fifty jxM dipyridamole failed to reduce the high percentage of platelets retained when heparinized human blood was passed through a glass bead column, but prolonged the inhibition of retention caused by disturbing blood in vitro. Possibly the prostheses act like disturbance. Although RA 233 was as effective as dipyridamole in inhibiting the return of retention, it was less effective in preventing the uptake of adenosine into erythrocytes, and more active in inhibiting ADP-induced aggregation and release. Thus there is no simple relation between these drug effects.

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