A beamforming method for plane wave Doppler imaging of high flow velocities

2016 ◽  
Author(s):  
Omar Mansour ◽  
Tamie L. Poepping ◽  
James C. Lacefield
1975 ◽  
Vol 14 (72) ◽  
pp. 395-406 ◽  
Author(s):  
Chalmers M. Clapperton

In Svalbard and Iceland there appears to be much more debris entrained in glaciers that surge than in those which do not. Conditions particularly favourable for the basal incorporation of debris develop as a consequence of the high flow velocities attained by a surge. These are increased cavitation in the lee of obstacles and an increased supply of basal melt water resulting from frictional heat and from the trigger zone. Layers of regelation ice incorporating debris can thus develop to a much greater vertical and horizontal extent than in non-surging glaciers. Excessive shearing, and the distortion of foliation structures in the terminal zone of compressive flow, enhance the vertical development of the debris-rich regelation layers. Glaciers that surge over outwash and/or fjord-bottom sediments become particularly rich in debris.


1980 ◽  
Vol 106 (11) ◽  
pp. 1827-1842 ◽  
Author(s):  
Subhash C. Jain ◽  
Edward E. Fischer

1981 ◽  
Vol 107 (7) ◽  
pp. 958-958
Author(s):  
Fred W. Blaisdell ◽  
Clayton L. Anderson

Author(s):  
M. P. Paidoussis

A flexible cylinder with pinned ends in axial flow of sufficiently high flow velocity is subject to buckling and oscillatory hydroelastic instabilities. These instabilities are discussed briefly and it is shown that they occur at such high flow velocities that they are not likely to be encountered in practice, unless the cylinder is made of very flexible material such as rubber. The cylinder is subjected to small amplitude vibration, however, even at flow velocities very much smaller than the critical velocities for hydroelastic instabilities. The mechanism of energy transfer from the fluid to the cylinder is examined and it is postulated that this vibration is excited by cross-flow components of flow and other departures from steady, uniform and perfectly axial flow. Experimental evidence supporting this postulate is presented. An empirical expression is given for the amplitude of vibration based on reported experimental observations covering a variety of geometries, fluids and cylinder materials.


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