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dc.contributor.authorTuong, T. P.
dc.date.accessioned2010-08-06T02:04:24Z
dc.date.available2010-08-06T02:04:24Z
dc.date.issued1972
dc.identifier.urihttps://hdl.handle.net/10182/2353
dc.description.abstractThe objective of this investigation was to improve the knowledge on the effect of rainfall on the general dynamics and physical aspects of shallow channel flows, especially the factors which have great influence on the eroding ability of the flow. The experimental study began with a detailed investigation of the interaction between a single raindrop and a stationary or flowing water body. Physical arguments based on hydrodynamic theories were given to explain the phenomena obtained by observation and stroboscopic and cine photography techniques. Dimensional analysis was used to determine the parameters by which the data from the raindrop impact experiments could be correlated. The fluid motion during the formation of the cavity, the upward jet, and the downward turbulent jet was studied and the general fluid flow fields during these periods were suggested. These sub-surface phenomena occurred after the impact and seemed to have greater effect in modifying the flow conditions than the impact itself. The bed material was found to be displaced either by the direct impact (when the water depth was less than the maximum depth of penetration of the raindrop), or by the fluid movement created by phenomena occurring after the impact (When the water depth was greater than the maximum depth of penetration of the raindrop), especially by the spreading action of the turbulent jet as it approaches the floor. Experimental studies of the effect of rainfall on the general dynamics of the flow were carried out in a 6.1m long by 0.5m wide tilting flume with perspex sidewalls. Rainfall was simulated by three 0.75m x 0.6m x 25mm rainfall modules. Within the experimental ranges rainfall was found to increase the mean bed shear stress, decrease the mean flow velocity. The velocity gradient was found to decrease near the water surface and increases near the channel floor when rainfall is applied. The explanation of the above changes in mean flow conditions were given in the light of the phenomena accompanying the single drop impact. The understanding on the effect of rainfall on the general dynamics of the flow was also gained from the re-derivation of the momentum and the energy equations governing the flows with rainfall. The disturbances created by single raindrop impacts and by the subsequent phenomena were also investigated quantatively by measuring the changes induced by the raindrops in the fluctuating components of the velocity of the main water body. This was then extended to a study of the effect of the multidrop rainfall on the turbulence characteristics of flowing water. Longitudinal turbulence intensity and energy spectra were found to change drastically, especially near the water surface, when rainfall was applied. Based on the results of this study, experimental research techniques are suggested for the investigation on the effects of rainfall on the sediment entrainment and suspension processes.en
dc.language.isoenen
dc.publisherLincoln College, University of Canterburyen
dc.rights.urihttps://researcharchive.lincoln.ac.nz/page/rights
dc.subjectrainfallen
dc.subjectshallow channel flowsen
dc.subjectchannel erosionen
dc.subjectsedimenten
dc.subjectentrainmenten
dc.subjectsuspensionen
dc.subjectraindropen
dc.subjectturbulenceen
dc.titleAn experimental investigation of rainfall-modified shallow channel flowsen
dc.typeThesisen
thesis.degree.grantorUniversity of Canterburyen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen
lu.thesis.supervisorPainter, D. J.
lu.thesis.supervisorBurton, J. R.
lu.contributor.unitDepartment of Environmental Managementen
dc.rights.accessRightsDigital thesis can be viewed by current staff and students of Lincoln University only. Print copy available for reading in Lincoln University Library. en
dc.subject.anzsrc040608 Surfacewater Hydrologyen


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