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Title DECELERATING OPEN CHANNEL FLOW OVER GRAVEL: TURBULENCE STRUCTURE & SENSOR DEVELOPMENT
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Publication Date
Degree Level doctoral
University/Publisher University of Kentucky
Abstract This dissertation describes investigations of fully turbulent decelerating hydraulically roughbed flow over gravel and the development of technology to measure turbulence and associated sediment transport in streams. Theory is developed for predicting velocity distributions in simple uniform flow using the asymptotic invariance principle and tested using laboratory and field collected data. A mixed scale is developed that accounts for bed derived turbulent structures throughout the flows depth and is used to parameterize the external boundary’s effect on the flow for the logarithmic and outer layers. The asymptotic invariance principle and similarity analysis is conducted for the equations of motion in the outer region of decelerating flow over gravel to define equilibrium conditions for this class of flows with the velocity scale is the freestream velocity. The combination of time series and time averaged statistical analysis of turbulent flow is used to elucidate the structure of flow under decelerating conditions. Time averaged statistical measures of turbulence confirm results of others for higher Froude number approaching transcritical and time series analysis shows the effects of decelerating flow on turbulence to be frequency dependent. Wireless velocity sensors were developed and found capable of measuring time averaged velocity and able to resolve macroturbulence from time series data. A semi-theoretical model of elastic deformation of cantilever beams under hydraulic forcing was coupled with circuit theory to develop a calibration procedure for the VBS that requires only three measurement points, one of which is at zero velocity. Light based sensors are developed to estimate light attenuation in water for ecological research or estimating sediment concentration in water. A semi-theoretical scaling of light attenuation and sediment properties was developed which predicts light attenuation from sediment properties. The combination of new theory on open channel velocity, turbulent structure and field sensors for measuring turbulence and sediment offers the possibility to extend our laboratory knowledge to realistic flow situations.
Subjects/Keywords Nonuniform flow; Channel; Macrtoturbulence; Sensors; Light Attenuation; Environmental Engineering; Hydraulic Engineering
Country of Publication us
Format application/pdf
Record ID oai:uknowledge.uky.edu:ce_etds-1027
Repository uky-diss
Date Retrieved
Date Indexed 2017-09-20

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…Chapter 6: Estimating Suspended Sediment Concentration in Streams by Diffuse Light Attenuation ............................................................................ 149 6.1 Summary…

…167 6.13 Tables and Figures .............................................................................................. 172 Chapter 7: Dimensionless Scaling of Diffuse Light Attenuation by Suspended Sediment…

light attenuation data presented in dimensionless form along with the power law equation 8 fit using the k-fold cross validation with k equal to 5).... .......... 176 Figure 6.6 Field demonstration of LASS: (a) graduate researchers…

…the development of the light attenuation sensor system (LASS). Development of LASS in conjunction with VBS should enable observations necessary to understand the interactions between suspended sediment transport and turbulence. Understanding…

…in some of the world’s most productive aquatic ecosystems (Kirk 1994). There exists a need to relate sediment properties to light attenuation. The results of this research includes advancements in the theory of open channel turbulence and…

light attenuation by sediment, unique data sets by which to validate theories, and technological advancements to aid in the measurement of open channel flow, turbulence, and suspended sediment concentration. These contributions may prove useful for the…

…the effects of turbulence and associated suspended sediment transport requires investigating the impacts of suspended sediment on the aquatic ecosystem. Suspended sediments reduce the light available for photosynthesis and may limit primary production…

…sediment, and water clarity: a review.” JAWRA Journal of the American Water Resources Association, 37(5), 1085-1101. DOI: 10.1111/j.1752-1688.2001.tb03624. Kirk, J. T. O. (1994) Light and photosynthesis in aquatic ecosystems, Cambridge…

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