Over the last decades, the necessity to discover new sources of renewable energy, in order to satisfy the energy requirement of our planet respecting the environment, is quite evident. One source can be found in plants that produce power by means of osmotic pressure through the mixing of fresh and salt water across a suitable membrane. The objectives of the present research is to assess the effects of the outflow that is discharged from the osmotic power plant into the repository water body. A vigorous program of experimental studies using modern field-revolving techniques will be carried out on a new system that is constructing by PRIN 2010- 2011 “Hydroelectric energy by osmosis in coastal areas” funds, supported by detailed mathematical modeling. The present study deals with the calibration of the numerical model with experimental results. The evaluation of the preliminary results shows a quite good agreement with the experimental data.

Water is vital for life, and aquatic ecosystems cover more than 75 per cent of the planet’s surface. The structure, biodiversity, productivity and functionality of aquatic ecosystems are very sensitive to any water quality changes. Aquatic ecosystems have long been used as receiving environments of wastewater discharges. Sewage in some countries is discharged untreated, and remains far from satisfactory even in other countries, degrading the ecosystem services. The discharge of these effluents in a receiving water body via single jet or multiport diffuser, buoyant or non-buoyant jets, reflect a number of complex phenomena. Discharge systems need to be designed to minimize environmental impacts. Therefore, a good knowledge of the interaction between the effluents, the discharge system and the receiving environments, which was the purpose of the hydraulic group of the technical University of Bari, is required in order to evaluate the mixing process and then the potential environment impacts.

Channel vegetation plays an important role in the aquatic-ecosystem health of rivers, streams, and constructed water courses. Vegetation can occupy the entire width or just part of the stream, leading to different features of the flow disturbances. In a natural environment, the aquatic vegetations have different characteristics. They appear as submerged or emerged, rigid or flexible, leafed or leafless, have branches or rods, and with high or low density. Obviously, the additional drag due to the vegetation presence increases the resistance to the channel flow and consequently the risk for flooding increases. Therefore, understanding of the flow dynamic of vegetated channel is of crucial importance to ensure successful implementation of the stream conception and management. According to previous studies it was observed that flow around large patches of vegetation is characterized by the formation of a shear turbulent mixing layer at the interface between the vegetated and open channels. Despite the many studies on flow in partly vegetated open channels, this issue remains of fundamental importance in order to better understand the interaction between the flow behavior and the canopy structure. In this study we propose a new theoretical approach, based on flow momentum equations, which are capable of modeling the flow pattern within the shear layer in the unobstructed domain, adjacent to the canopy area. Details regarding the evolution of the shear layer and the turbulence structures are presented. New observations on the flow momentum exchange between the obstructed and unobstructed domains are illustrated. To validate the proposed theoretical model, many experiments were carried out on a physical model of a very large rectangular channel (4x15x0.4m) with the presence of an array of vertical, rigid and circular steel cylinders. The array of cylinders was partially mounted on the bottom of the channel, in the central part, leaving two lateral areas of free flow circulation near the walls. The three-dimensional flow velocity components were measured using a 3D Acoustic Doppler Velocimeter ADV. In contrast to the complexity of the flow distribution within canopies, in the unobstructed flow area, independently on the canopy characteristics, it was observed that the flow distribution always resembles a boundary layer feature. This implies the possibility of an easy flow interpretation at this area, which was the aim of this study. In this study, a simple expression of the main equilibrium flow velocity, at the interface between both domains, was determined as a function of the lateral positions. This expression was derived using the proposed theoretical approach and then experimentally proved. Based on the analysis of the experimental data, in this model we take into consideration the additional contribution of the secondary flow velocity component on the flow momentum balance, which was neglected in previous studies. Since it was observed tha

La situazione dell’intero territorio che si affaccia sui Mari di Taranto è alquanto complessa e risente certamente della presenza e della concentrazione di attività industriali e militari a forte impatto ambientale, tanto da rendere necessaria l’inclusione dell’area tarantina nel novero dei SIN (Siti di Interesse Nazionale) così come individuati dal Programma Nazionale di Bonifica e di Ripristino Ambientale (D.M. 18 settembre 2001 n. 468). Per quanto riguarda l’ambiente acquatico, la presenza e distribuzione dei contaminanti ed il loro accumulo, soprattutto nei sedimenti e nel biota dei Mari di Taranto è potenzialmente legato a processi di trasporto (attraverso le acque sotterranee, il dilavamento dei terreni, ecc.) nonché all’idrodinamica dei bacini (flussi di marea, correnti, ecc.) e all’influenza delle attività antropiche negli stessi (prelievo di acque ai fini industriali, movimentazione di mezzi navali all’interno dei bacini, ecc.). Diversi studi condotti nel corso degli anni sulla contaminazione dell’area marina costiera di Taranto hanno riguardato la caratterizzazione dei sedimenti marini da inquinanti organici, evidenziando criticità ambientali. Risulta pertanto imprescindibile una continua attività di monitoraggio ambientale nei Mari di Taranto, che può trovare un supporto anche nella modellistica numerica. In precedenti ricerche si è già sottolineato quanto siano numerose le azioni forzanti che condizionano la circolazione e, quindi, la diffusione di inquinanti in quest’area target. Nel presente studio, pertanto, si è proceduto nel modo seguente. Si sono acquisite la batimetria e le principali grandezze del clima meteo-marino dell’area. Successivamente sono state effettuate diverse misure di campo della corrente marina mediante un profilatore acustico Doppler (ADCP) montato su una barca, che ha fornito set completi di dati sull’intera colonna d’acqua. Durante le campagne di misura si è utilizzata anche una sonda CTD per la misura della salinità e della temperatura alle varie profondità investigate e, infine, è stato usato un anemometro per la misura della velocità e direzione del vento. In questo modo, per le singole giornate di misura, è stato possibile redigere delle mappe della velocità della corrente (orizzontale è verticale), della salinità e della temperatura a differenti profondità. Si è installata inoltre in Mar Grande, nell’ambito del progetto RITMARE, con fondi PON R&C 2007-2013, una stazione meteo-oceanografica i cui dati correntometrici sono stati analizzati con riferimento ad alcuni periodi di interesse. Si tratta di informazioni essenziali per comprendere alcuni trend caratteristici ed alcune situazioni tipiche del bacino, ancorché fortemente influenzate dalle condizioni contingenti dei giorni in cui le misure sono state condotte. Pertanto, le informazioni acquisite non possono essere generalizzate. Ad ogni modo risultano essenziali per la calibrazione del modello numerico adottato per la riproduzione della circola

This paper deals with measurements of the three-velocity components of a vertical, round, turbulent jet discharged into a vegetated cross flow. Over the last years, a large number of experimental studies and numerical models on turbulent jets discharged into a cross flow have been carried out, as well as several studies on vegetated channels. However, these studies show a lack of data regarding the combination between the vegetated channels and jets. The present study aimed at obtaining a more thorough understanding of the vegetation effects on the jet behaviors. To simulate the vegetation, arrays of emergent, rigid, circular steel cyl-inders were used. The jet source was placed at the centre of the experimental vegetated area. The time-averaged velocity field was investigated in the longitudinal, cross and horizontal planes of the channel. The results show that vegetation has significant effects on the jet structure as compared with the case of non-vegetated channel. Above all, the rigid stems reduce streamwise velocities, giving rise to an increase of the jet penetration height within the ambient flow. Moreover, the familiar pair of counter-rotating vortices and kid-ney shape observed in the cross section of the jet discharged into the non-vegetated channel disappears and transforms under the effects of stems into a complex flow motion structure for the jet discharged into the vegetated flume.

A Southern Adriatic coastal current is examined in the present paper, on the basis of some measurements carried out offshore Bari town in the Southern Adriatic Sea (South Italy) by means of a Vessel Mounted Acoustic Doppler Velocity Profiler (VM-ADCP). During the investigations, the current flow appeared unidirectional, i.e. mainly directed towards South-East, with decreasing velocities with increasing depth, as expected. In the present case, the 3D model MIKE 3FM by DHI was used to reproduce the hydrodynamics in the examined area. The computational domain was discretized by a mesh, with a finer resolution approaching the coastline. The input forcings used in model were the time-varying tidal elevation measured by the National Mareographic Network and the time-varying satellite wind field recorded by the National Research Council (NRC), relatively to the survey period. To run the model in baroclinic mode also the average sea temperature and salinity of the period were used as input conditions. Firstly, the model was calibrated, by tuning some critical parameters such as the wind drag coefficient and the bottom friction, in order to reach the best agreement between field measurements and model results. Successively, the vulnerability of the analyzed area was also checked, simulating the possible dispersion of polluting substances, due to the outflow of the Bari North wastewater plant. With this approach, some risk maps could be obtained as model outputs, which could be of great support in both planning and managing coastal activities.

Within the study of artificial waves generated in laboratory, numerical simulations of the wave fields determined by piston-type wavemakers were carried out by means of Computational Fluid Dynamics. For the numerical wave flumes, two different commercial codes, namely CFX and FLUENT, were used solving the unsteady, two-dimensional Navier-Stokes equations and applying the Volume Of Fluid methodology to deal with the different phases. In this way it was possible to calculate the wave propagation and analyze the generated incident waves. The accuracy of the numerical results in terms of wave profiles and propagation were assessed by comparison with an analytical solution available in literature showing a very good agreement of both the numerical results with the theoretical data. Moreover, a preliminary study was performed considering a more complex wave field which propagates in a simplified constant-slope coastal model.

Nowadays, dredging operations are ever more needed in ports and internal waterways, as well as in superficial water bodies, such as rivers, natural and artificial basins, in order to both improve and increase their navigability. On these special operations, part of the finer material that is got again in suspension could be a nuisance source for the underwater environment, as the produced cloudiness and the possible toxic substances that are associated to it can interact with the aquatic ecosystem. Therefore, during the dredging activities, phenomena like the increase of cloudiness, concentration of material in suspension, chemical oxygen demand, nutrients spreading and the decrease of the dissolved oxygen occur, with negative consequences on the benthonic fauna and on the organisms of the water column. In order to minimize these environmental impacts, it is important to define the dredging operational modes. They are correlated to the bathymetric and hydrodynamic conditions of the water body, to the chemical-physical characteristics of the sediment, to the distance and the characteristics of the settling area and eventually to the kind of treatment to which the sediment will be subjected. A practical application about the environmental implications related to dredging operations is dealt with in the present study, whose purpose is firstly the modeling of the hydrodynamics inside the harbor of a city located in the Southern Italy and then the simulation of dredged sediments in the same area. The dredging operation of the port area was hypothesized with the use of both hydraulic and mechanical dredges and the consequent sediment transport was studied, so that the impact of the operations on the aquatic environment could be considered. Results show that the modeling of such complex technical operations is an important tool for their best planning.