Pulsatory characteristics of wind velocity in sand flow over typical underlying surfaces

2007 ◽  
Vol 50 (2) ◽  
pp. 247-253 ◽  
Author(s):  
KeCun Zhang ◽  
JianJun Qu ◽  
RuiPing Zu ◽  
HaiYan Fang
Keyword(s):  
1968 ◽  
Vol 48 (1) ◽  
pp. 49-52 ◽  
Author(s):  
Frederick Bisal

A wind tunnel was used to study the effect of various amounts of standing wheat stubble on sand flow. In general, the relationship between sand flow and the amount of wheat stubble tended to be sigmoidal. There was an initial phase when small amounts of stubble had very little effect on sand flow, followed by a very rapid decrease in flow when additional increments of stubble were added to the surface. Sand flow approached zero at stubble rates ranging from 1,200 kg/ha for a wind velocity of 5.36 m/sec to 7,200 kg/ha for a wind velocity of 8.49 m/sec. At a wind velocity of 10.28 m/sec the addition of 1,800 kg/ha of wheat stubble tended to increase sand flow.


2012 ◽  
Author(s):  
Marc Emond ◽  
Doug Vandemark ◽  
James Forsythe ◽  
Albert J. Plueddemann ◽  
J. Thomas Farrar

2021 ◽  
pp. 1420326X2110160
Author(s):  
Kai Yip Lee ◽  
Cheuk Ming Mak

This study investigated effects of incident wind angles on wind velocity distributions in wakes of two generic building configurations, namely, ‘T’- and ‘+’-shaped, and the air pressure distributions along their leeward walls by using computational fluid dynamics simulations. Results show that when the wind approaches laterally (90°) (vs. when the wind is direct (0°)), the downwind length and maximum bilateral width of the low-wind velocity zone in the wake of ‘T’-shaped building decrease by 11.5% and 37.9%, respectively. When the incident wind is oblique (45°) (vs. when it is direct), the length and width of this low-wind velocity zone in the wake of ‘+’-shaped building decrease by 15.0% and 30.9%, respectively. Furthermore, results show that the air pressure on the leeward walls of the ‘T’- and ‘+’-shaped buildings gradually decreases along with the building height. The resulting low-wind conditions on upper floors of buildings reduce the fresh air intake of their leeward units utilizing natural ventilation. It is particularly apparent in the case of direct approaching wind. Thus, the appropriate selection of building configurations and their orientations allows for the most effective use of wind to enhance ventilation in indoor and urban environments.


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