Search results for "flow [Keywords]"

Assessing flow resistance law in vegetated channels by dimensional analysis and self-similarity

2019

Abstract In this paper experimental data collected by Kouwen et al., Wilson and Horrit, Raffaelli et al. and Carollo et al., using straight flumes having a bed covered by grass-like vegetation with different stem concentrations, were used to analyze flow resistance for flexible submerged elements. At first, the dimensional analysis and the incomplete self-similarity hypothesis was applied to deduce the flow velocity distribution and the resulting theoretical expression of the Darcy-Weisbach friction factor. Then, a relationship between the Γ function of the velocity profile and the biomechanical characteristics of vegetation, the channel slope, the Reynolds number and the flow Froude number…

Flow resistance due to shrubs and woody vegetation

2023

In this paper, a theoretical open channel flow resistance equation was verified using flow depth and discharge measurements carried out by Freeman et al. in a large channel, 2.44 m wide, for ten different types of uniform-sized plants (shrubs and woody vegetation). The plants, which are broadleaf deciduous vegetation commonly found in floodplains and riparian zones, were placed in staggered rows inside the channel whose bed was constructed to accept plants with their root systems. For each species, the available measurements were carried out by Freeman et al. with plants having different values of plant density, height, and bending stiffness. The available literature database (87 measuremen…

Assessing theoretical flow velocity profile and resistance in gravel bed rivers by field measurements

2018

Previous studies showed that integrating a power velocity profile, deduced applying dimensional analysis and the incomplete self-similarity condition, the flow resistance equation for open channel flow can be obtained. At first, in this paper the relationship between the Gamma function of the power velocity profile, the channel slope and the Froude number, which was already empirically introduced in a previous paper, is now theoretically deduced. Then this relationship is calibrated using the field measurements of flow velocity, water depth and bed slope carried out in 101 reaches of gravel bed rivers available by literature. The proposed relationship for estimating Gamma function and the t…

Studio sperimentale sulle resistenze al moto di correnti nei rill

Closure to "Applying hypothesis of self-similarity for flow-resistance law in calabrian gravel-bed rivers" by Vito Ferro and Paolo Porto

2019

This Closure is a paper in which the Authors answer to the queries of a Discusser.

Modelling strategies for the reduction of fat dormice in northern Italian hazel groves

2018

The production of hazelnuts represents an important resource for several Italian rural areas. Sicily and Piedmont, two of the most important producers of hazelnuts, are affected by the presence of the dormouse (Glis glis), that has considerably severely harmed the production of hazelnuts. This study aims to analyse the issue in the Province of Cuneo in Piedmont and to evaluate the sustainability of the policies implemented by using the system dynamics (SD) methodology. An SD predator-prey microworld was built to reproduce the main relevant cause and effect relationships between the development of the dormouse population and local hazelnut production. The results of the SD microworld simulat…

Exploring relationships between pixel size and accuracy for debris flow susceptibility models: a test in the Giampilieri catchment (Sicily, Italy).

2014

Debris flows are among the most hazardous phenomena in nature, which typically take the form of multiple-occurrence regional landslide events triggered by intense driving inputs such as storms or earthquakes. The main tasks of this study were to verify whether cell-based susceptibility models is capable of predicting debris flow initiations in the Giampilieri catchment (southern Italy) and to explore the relationships between the pixel size of the adopted mapping units in terms of predictive performances of the derived models. The Giampilieri catchment is a small area (10km 2 ) hit by a storm on the 1 st October 2009 which resulted in the triggering of more than one thousand landslides and …

INFLUENCE OF POSIDONIA OCEANICA MEADOW DENSITY ON FLOW RESISTANCE IN SHALLOW WATERS

2008

Aquatic vegetation considerably affects circulation in water bodies with influence increasing as the depth decreases. On the other hand, increasing use of mathematical circulation models for management of coastal sea waters, lagoons and marshes requires determination of such effects and in particular of flow resistance. A typical plant of inshore sandy beds, less than 40 m deep, in the Mediterranean Sea is Posidonia oceanica, which is constituted by a tuft of very thin and flexible ribbon-like leaves about 1 cm wide and up to 1.5 m long. This plant forms meadows with areal density usually ranging between 500 and 1000 plants/m2. Because of its characteristics, Posidonia oceanica constitutes …

Aerobic granular sludge: State of the art, applications, and new perspectives.

2018

The aerobic granular sludge (AGS) process has attracted significant interest over the last decade and is one of the most promising wastewater treatment technologies. AGS offers several advantages over conventional activated sludge (CAS) including excellent settling, and higher volumetric loading capacity. Because of porosity, concentration gradients develop and stratified aerobic, anoxic, and anaerobic layers develop throughout granule depth. This is the reason for simultaneous nutrient removal in a single tank. Aerobic granulation is influenced by many parameters including wastewater characteristics and operating conditions. Among these, the anaerobic upflow feeding strategy and a properly…

Photocatalytic process intensification by coupling with pervaporation

2011

The integration of photocatalysis with a membrane separation process, in particular pervaporation, permits the recovery of valuable intermediate compounds (aromatic aldehydes) while they are produced avoiding their further degradation in the reactive ambient. In this way the yield and the conversion are enhanced. The coupling of the two processes is straightforward and the integration is complete even maintaining pervaporation and photocatalysis in two separate apparatuses provided that the process stream is continuously recycled at a sufficiently high flow rate. Additional advantages are: higher degree of purification of the aldehyde in the powder-free product stream, semicontinuous produc…