The research project described in this thesis concerns the study of the bed load sediment transport at the grain scale. It was developed mainly with the aims of analyzing the kinematical properties of bed load moving sediments (sliding, rolling and jumping grains) for weak sediment transport conditions in a quasi one-dimensional turbulent flow field, studying their dependence on the spatial and temporal support scales and identifying the main physical mechanisms which affect sediment kinematics at the different scales. Differently from the previous studies, a great deal of effort was put into clearly describing the tested flow and transport conditions, and the scales at which particle motion was studied. This work comprehends both classical analyses, as the study of the characteristics of particle trajectories (e.g. length, duration), and more innovative ones, as the study of particle diffusion or of the scaling properties of the geometric structure of sediment trajectory. The leitmotiv of all the analyses is to acquire a proper knowledge of the scale-dependence of statistical variables characterizing sediment transport. All these efforts aim either at developing new understanding of sediment transport phenomena or at allowing a sound interpretation of these results and of those from other researches.
In questa tesi viene presentato un lavoro di ricerca riguardante il moto dei sedimenti per basse intensità di trasporto. Sono state analizzate le caratteristiche cinematiche dei sedimenti trasportati da un flusso turbolento quasi-1D e la loro dipendenza dalle scale spaziali e temporali di riferimento. L’obiettivo principale del progetto è stato identificare i fenomeni che governano il moto dei sedimenti al variare delle scale utilizzate nelle analisi. Per consentire il confronto tra i risultati ottenuti e quelli ricavati da altri studi, si è data particolare attenzione alla descrizione delle condizioni sperimentali per cui il moto dei sedimenti è stato studiato. Questo lavoro comprende sia analisi “classiche”, come lo studio delle caratteristiche delle traiettorie (ad esempio la loro lunghezza o durata), che altre più innovative. Queste ultime riguardano il processo diffusivo dei sedimenti e il comportamento frattale delle loro traiettorie. Lo studio è stato condotto con lo scopo di contribuire ad ampliare la conoscenza dei fenomeni che governano il trasporto solido e di fornirne un modello interpretativo coerente.
Characterization of bed load sediment transport at the grain scale
CAMPAGNOL, JENNY
Abstract
The research project described in this thesis concerns the study of the bed load sediment transport at the grain scale. It was developed mainly with the aims of analyzing the kinematical properties of bed load moving sediments (sliding, rolling and jumping grains) for weak sediment transport conditions in a quasi one-dimensional turbulent flow field, studying their dependence on the spatial and temporal support scales and identifying the main physical mechanisms which affect sediment kinematics at the different scales. Differently from the previous studies, a great deal of effort was put into clearly describing the tested flow and transport conditions, and the scales at which particle motion was studied. This work comprehends both classical analyses, as the study of the characteristics of particle trajectories (e.g. length, duration), and more innovative ones, as the study of particle diffusion or of the scaling properties of the geometric structure of sediment trajectory. The leitmotiv of all the analyses is to acquire a proper knowledge of the scale-dependence of statistical variables characterizing sediment transport. All these efforts aim either at developing new understanding of sediment transport phenomena or at allowing a sound interpretation of these results and of those from other researches.File | Dimensione | Formato | |
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2013_03_PhD_Campagnol_01.pdf
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2013_03_PhD_Campagnol_02.pdf
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https://hdl.handle.net/10589/74204