Efficiency of a digital particle image velocimetry (DPIV) method for monitoring the surface velocity of hyper-concentrated flows

Digital particle image velocimetry records high resolution images and allows the identification of the position of points in different time instants. This paper explores the efficiency of the digital image-technique for remote monitoring of surface velocity and discharge measurement in hyper-concentrated flow by the way of laboratory experiment. One of the challenges in the application of the image-technique is the evaluation of the error in estimating surface velocity. The error quantification is complex because it depends on many factors characterizing either the experimental conditions or/and the processing algorithm. In the present work, attention is devoted to the estimation error due …

Roots Characteristics of a flexible and mature vegetation: Preliminary results of experimental investigation in a meandering laboratory flume

Vegetation controls sediment dynamics and affects the kinematic characteristics of flow in rivers. The uprooting mechanism is strongly affected by mechanical properties, morphology and branching of the roots system. This work presents preliminary results of experimental work conducted in a laboratory meandering flume. The work aims to investigate how the geometrical and mechanical characteristics of the roots of a real, flexible and mature vegetation could vary along the bend. Results show that both the geometrical and the mechanical characteristics of the roots assume higher/lower values in peculiar sections of the bend suggesting that they could be affected by the kinematic characteristic…

Jets interacting with vegetation in the rotating LEGI platform

Rivers and wastewater discharges flowing into lakes and coastal waters strongly affect aquatic ecosystems, based on their transport of turbulence, tracers and sediment particles. Mixing and spreading of outflows have an even greater impact when the receiving site is obstructed by vegetation canopies or mussel cultivation farms. Thus, a thorough knowledge of the interaction between effluents and receiving bodies is required to mitigate impacts and promote best environmental management practices, also following the 2015 EU Marine Strategy Framework Directive.

Flow-induced vegetation uprooting in a meandering bend : experimental investigation

Abstract Vegetation uprooting is a complex process which depends on many interrelated factors. In this paper, attention is focused on the flow-induced uprooting in river bends, where the flow characteristics vary as effected by the channel's curvature and its continuous changing in the downstream direction. Results are presented by an experimental work done in a high-amplitude meandering flume with mature herbaceous vegetation on the bed. In the first part of the paper, the variation along the bend of the geometrical (length, thickness, and radical architecture) and the mechanical (resistance force) characteristics of the roots are analyzed. In the second part of the paper, the transition f…

Turbulence structure and implications in exchange processes in high-amplitude vegetated meanders: Experimental investigation

Aquatic plants in rivers interact with flow and exert an important role in maintaining suitable habitat and ecological equilibrium. Understanding turbulence structure in the presence of vegetation is important with respect to environmental processes, such as sediment transport and mixing of transported quantities. Literature indicates that mass and momentum exchanges in the presence of vegetation are strongly influenced by the sequence of coherent structures which form between vegetated and non-vegetated zones. In the present paper we investigate turbulence structure and coherent motion in high-curvature channels with submerged vegetation. The analysis is performed with the aid of detailed …

Digital image-based technique for monitoring surface velocity: sensitivity analysis with processing parameters using data of a study case

This paper describes the application of image-based technique for mapping surface velocity of hyper-concentrated flows. The analysis is conducted with the aid of data collected in a scale laboratory flume constructed at the Hydraulic laboratory of the Department of Civil, Environmental, Aerospatial and of Mate-rials Engineering (DICAM) – University of Palermo (Italy). A fully digital images-based technique has been applied to record a large amount of high resolution images identifying simultaneously the position of points in different time instants. The sensitivity analysis of the estimated flow velocity with the acquisition conditions and the number of processed frames is performed

Studio dell’interazione corrente-vegetazione in un alveo meandriforme di elevata ampiezza in presenza di vegetazione sommersa matura e non ed al variare della distribuzione

Hyper-concentrated flow and surface velocity estimation by digital imaging technique: a study case

This paper investigates the utility of digital imaging technique for performing surface velocity measurements of hyper-concentrated flows. The analysis is conducted with the aid of data collected in a scale laboratory flume constructed at the Hydraulic laboratory of the Department of Civil, Environmental, Aerospatial and of Materials Engineering (DICAM) – University of Palermo (Italy). In particular the present paper describes the setup of a laboratory test and the applicability of a fully digital imaging approach.