IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
Log On
About IAHRDirectoryCommitteesMy IAHRNews & JournalseLibraryeShopEventsJoin IAHRWorld CongressDonate
spacer.gif
spacer.gif eLibrary
spacer.gif eLibrary
You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Hydro-environment : Modeling of gradually-varied flow through submerged semi-rigid blade-type vegetation
Modeling of gradually-varied flow through submerged semi-rigid blade-type vegetation
Author : BUSARI, AFIS OLUMIDE(1) & LI, CHI WAI(2)
ABSTRACT
The condition of flow through a vegetation patch is gradually-varied. The drag generated by vegetation depends on the
shape of each piece of vegetation and the flow interaction among the vegetation elements. Some vegetation is of bladetype
which has different drag characteristics as compared to the circular-cylinder type vegetation. In the present study
experiments are carried out to investigate the hydrodynamic behavior of gradually-varied flow through blade-type
vegetation. Particular attention is focused on the effect of distribution pattern of vegetation elements on the total drag
generated by a vegetation patch. The values of the density parameter of vegetation ( = Nbv , N is areal density, bv is the
blade width) are 72, 48, 24, 18, 15, 12, 6 and 3 (1/m). The blade Reynolds number Re using the blade width as the
length scale ranges from 670 to 1110 and six flow rates are used in each set of experiments. Theoretical longitudinal
momentum equation relating the vegetation resistant force, water surface slope and mean velocity in the vegetation
layer is used to determine the averaged drag coefficient Cd. Using a regular-array pattern of vegetation elements, the
sheltering effect and channeling effect are studied separately by varying the longitudinal element spacing (Sx) and lateral
element spacing (Sy) respectively. For a constant lateral element spacing (Sx), Cd decreases with increasing areal
density of vegetation due to sheltering effect. For a constant longitudinal spacing (Sy), Cd increases with increasing areal
density of vegetation due to channeling effect. The results show that apart from the density parameter , the distribution
pattern of vegetation elements can exert significant effect on the drag coefficient and the associated flow characteristics.
File Size : 764,935 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Hydro-environment
Date Published : 13/08/2015
Download Now