Main Title |
Obstacle Drag in Stratified Flow. |
Author |
Castro, I. P. ;
Snyder, W. H. ;
Baines., P. G. ;
|
CORP Author |
Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab. ;Surrey Univ., Guildford (England). Dept. of Mechanical Engineering. ;Commonwealth Scientific and Industrial Research Organization, Aspendale (Australia). Div. of Atmospheric Research. |
Publisher |
c1990 |
Year Published |
1990 |
Report Number |
EPA/600/J-90/185; |
Stock Number |
PB91-116814 |
Additional Subjects |
Atmospheric motion ;
Fluid flow ;
Drag ;
Stratification ;
Inviscid flow ;
Turbulent flow ;
Wakes ;
Reynolds number ;
Three dimensional flow ;
Lee waves ;
Air currents
|
Holdings |
Library |
Call Number |
Additional Info |
Location |
Last Modified |
Checkout Status |
NTIS |
PB91-116814 |
Some EPA libraries have a fiche copy filed under the call number shown. |
|
07/26/2022 |
|
Collation |
25p |
Abstract |
The paper describes an experimental study of the drag of two- and three-dimensional bluff obstacles of various cross-stream shapes when towed through a fluid having a stable, linear density gradient with Brunt-Vaisala frequency, N. Drag measurements were made directly using a force balance, and effects of obstacle blockage (h/D, where h and D are the obstacle height and the fluid depth, respectively) and Reynolds number were effectively eliminated. It is shown that even in cases where the downstream lee waves and propagating columnar waves are of large amplitude, the variation of drag with the parameter K (=ND/U) is qualitatively close to that implied by linear theories, with drag minima existing at integral values of K. Under certain conditions large, steady, periodic variations in drag occur. Simultaneous drag measurements and video recordings of the wakes show that this unsteadiness is linked directly with time-variations in the lee and columnar wave amplitudes. It is argued that there are, therefore, situations where the inviscid flow is always unsteady even for large times; the consequent implications for atmospheric motions are discussed. |
Supplementary Notes |
Pub. in Proceedings of the Royal Society of London A 429, p119-140 1990. See also PB87-167748. Prepared in cooperation with Surrey Univ., Guildford (England). Dept. of Mechanical Engineering, and Commonwealth Scientific and Industrial Research Organization, Aspendale (Australia). Div. of Atmospheric Research. |
NTIS Title Notes |
Journal article. |
Category Codes |
55B; 46B |
NTIS Prices |
PC A03/MF A01 |
Primary Description |
600/09 |
Document Type |
NT |
Cataloging Source |
NTIS/MT |
Control Number |
101123703 |
Origin |
NTIS |
Type |
CAT |