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

Real time current measurements using an AWAC Acoustic Doppler Current Profiler (ADCP) were carried out on February 2010 inside and outside the Port of Bari, located in the Southern Italy, along the Adriatic Sea. These surveys represent part of a wide field data collection program, whose aim is to study and model the hydrodynamics and water quality of the Port of Bari and its surrounding areas.The principal purpose of the present work is to analyze the current circulation in the port. Useful information referring to sedimentation processes and possible pollutants dispersion can be derived from the collected current data. Moreover, the same measurements can be used as input data for the calibration of numerical models able to simulate the current patterns in the target area. Data collected are of crucial importance for the port management and monitoring of water aquatorium. Key words: Current measurements, Port of Bari, Hydrodynamic, Current circulation, Numerical models, Monitoring.

Velocity data, undertaken during a survey carried out in March 2010, offshore the coast of Bari (located on the Adriatic Sea in Southern Italy), are analysed and discussed in the present paper. Measurements were acquired by means of a Vessel Mounted Acoustic Doppler Velocity Profiler (VM-ADCP). Furthermore, some data about current temperature and salinity were also collected at the same time and locations. The current flow was south-eastward directed during the investigations and it had a quite homogeneous direction along the vertical, while velocity intensities diminished whit deepening waters. Some numerical simulations were run to reproduce the coastal hydrodynamics. They were forced by the real wind and tide and confirmed the investigated current pattern. Also the vertical profiles of measured current velocities were studied and compared with some experimental laws, such as the logarithmic law, usually used to reproduce uniform flows in simple channel configurations. A successful validation of the experimental laws was achieved.

An analytical study for the prediction of shallow flow motions in a very large partially vegetated channel with a free surface is presented. As observed by some previous studies, at the interface between the vegetated and non-vegetated domains, the shear layer was found to possess two distinct length scales. An inner-layer thickness establishes by the array resistance and a wider outer region, which resembles a boundary layer, has a width set by the water depth and bottom friction. In this study, we shall try to reveal some other attitudinal flow patterns at the interface between the two domains. Details regarding the evolution of the shear layers, the turbulence structures and momentum exchange are presented. To validate the proposed analytical model, a large series of experiments was carried out in a very large rectangular channel with presence of partially array of vertical, rigid, circular steel cylinders. The three-dimensional flow velocity components were measured using a 3D Acoustic Doppler Velocimeter ADV.

This paper describes a theoretical approach of longitudinal turbulent flow in an infinite square array of emergent rigid vegetation distributed uniformly along a channel bottom. Laboratory experiments were carried out to investigate the flow velocity characteristics in order to confirm this theoretical approach. The vegetation was simulated by an array of straight, rigid, circular and rough iron cylinders mounted on the bed of a recirculating hydraulic flume. Measurements of the threedimensional flow velocity components were taken using a 3D Acoustic Doppler Velocimeter ADV. The formulation proposed is consistent with the experimental data for a specific range of the Reynolds number. In addition, a new formula to estimate the bulk drag coefficient CD of the vegetation is suggested and validated.

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.

Despite the many studies on flow in partly obstructed open channels, this issue remains of fundamental importance in order to better understand the interaction between flow behavior and the canopy structure. In the first part of this study we suggest a new theoretical approach able to model the flow pattern within the shear layer in the unobstructed domain, adjacent to the canopy area. Differently from previous studies, the new analytical solution of flow momentum equations takes into account the transversal velocity component of the flow, which is modelled as a linear function of the streamwise velocity. The proposed theoretical model is validated by different experiments carried out on a physical model of a very large rectangular channel by the research group of the Department of Civil, Environmental, Building Engineering and Chemistry of the Technical University of Bari. An array of vertical, rigid, and circular steel cylinders was partially mounted on the bottom in the central part of the flume, 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. A comparison of the measured and predicted data of the present study with those obtained in other previous studies, carried out with different canopy density, show a non-dependence of this analytical solution on the array density and the Reynolds number. In the second part of the paper, detailed observations of turbulent intensities and spanwise Reynolds stresses in the unobstructed flow are analyzed and discussed. Differently from some earlier studies, it was observed that the peak of the turbulence intensity and that of the spanwise Reynolds stress are significantly shifted toward the center of the shear layer.

The coastal areas neighbouring wastewater outfalls are particularly sensitive and vulnerable, therefore they should be continuously monitored. The present paper examines the results of a monitoring survey carried out in July 2001 offshore the Bari town, in the Southern Adriatic Sea (South Italy), close to the outfall of its wastewater treatment plant, named Bari East. Measurements of horizontal and vertical velocity components were carried out with a Vessel Mounted Acoustic Doppler Profiler. Also salinity and temperature were assessed at the same time and locations by means of a CTD probe. The investigation confirms the pivotal role played by currents magnitude and direction, wind, tide and stratification in the process of diffusion and dispersion of passive tracers (such as temperature and salinity). As a second step, the MIKE 3FM, a 3D numerical model by the Danish Hydraulic Institute (DHI) is tested to reproduce the hydrodynamic current pattern and the diffusion of the plume in the target area. The model was implemented with initial and boundary conditions relative to the survey day and the assessed measurements were used to calibrate it, by tuning some parameters, such as the wind drag coefficient, the bottom roughness and a turbulence closure model coefficient. A satisfactory agreement was found between field measurements and model results, showing that in the target area the modelled hydrodynamics was prevalently influenced by the wind drag coefficient and less affected by bottom roughness and turbulence. The present approach confirms that, once calibrated and validated, a numerical model could be a powerful instrument to support both planning and management of coastal activities. In fact, it could allow to predict the possible dispersion of a polluting tracer when a scenario is established, thus providing some useful maps of spreading.

It can be seen in literature that the fundamental factors governing oblique shock wave development, typically in very large channels with straight sidewalls, have not yet been completely understood and remain at the level of indicating its presence and formation. In this study, some aspects of boundary layer development and its detachment from the channel lateral sidewall are investigated. At the detachment point of the lateral shock waves, it was noted that the displacement thickness experiences a significant increase; this is accompanied by a significantly reduced gradient normal to the channel side-walls of the flow velocity as well as the occurrence of a strong, sudden adverse pressure gradient. Furthermore, it is argued that the supersonic flow separation analogy with a supercritical free surface flow can be applied to this case study and that the behavior of the supercritical flow during separation can be interpreted by the free interaction theory.

The dynamics of regular breaking waves has been both widely and successfully investigated. In any case, many natural coastal processes are commonly due to irregular breaking waves, the behaviour of which requires thorough study. The present research aims to investigate the distributions of the wave and turbulent Reynolds shear stresses in a laboratory irregular wave, characterized by a narrow banded spectrum, which develops on a sloping sand bottom, in intermediate waters. Experiments focused on the wave shoaling region, in order to analyze the effects of breaking induced turbulence outside the surf zone, taking into account that turbulence is not limited to the breaking region but it spreads also outside the surf zone. The phase-averaging technique was used to separate the turbulent components from the steady ones. All the analysed values derive directly from real measurements and are not interpolated. Moreover, a 3D Acoustic Doppler Velocimeter was adopted to measure the wave velocity, consequently the longshore component of the velocity is also available to estimate the shear stresses. These experimental data were also used to test some literary numerical models and relevant results have been obtained, which confirm the outputs of the abovementioned models in the cases of non dissipative waves propagating above a flat bottom and dissipative waves propagating over a sloping bottom.