Experimental and Numerical Analysis of the Hydrodynamics around a Vertical Cylinder in Waves

The present study provides an extensive analysis on the hydrodynamics induced by a vertical slender pile under wave action. The authors carried out the study both experimentally and numerically, thus enabling a deep understanding of the flow physics. The experiments took place at a wave flume of the Universita Politecnica delle Marche. Two different experimental campaigns were performed: In the former one, a mobile bed model was realized with the aims to study both the scour process and the hydrodynamics around the cylinder; in the latter one, the seabed was rigid in order to make undisturbed optical measurements, providing a deeper analysis of the hydrodynamics. The numerical investigation was made by performing a direct numerical simulation. A second order numerical discretization, both in time and in space, was used to solve the Navier-Stokes equations while a volume of fluid (VOF) approach was adopted for tracking the free surface. The comparison between experimental and numerical results is provided in terms of velocity, pressure distributions around the cylinder, and total force on it. The analysis of the pressure gradient was used to evaluate the generation and evolution of vortices around the cylinder. Finally, the relation between scour and bed shear stresses due to the structure of the vortex pattern around the pile was assessed. It is worth noting that the physical understanding of this last analysis was enabled by the combined use of experimental data on scour and numerical data on the flow pattern

On the lookout for influenza viruses in Italy during the 2021-2022 season: along came A(H3N2) viruses with a new phylogenetic makeup of their hemagglutinin

Aims: To assess influenza viruses (IVs) circulation and to evaluate A(H3N2) molecular evolution during the 2021-2022 season in Italy. Materials and methods: 12,393 respiratory specimens (nasopharyngeal swabs or broncho-alveolar lavages) collected from in/outpatients with influenza illness in the period spanning from January 1, 2022 (week 2022-01) to May 31, 2022 (week 2022-22) were analysed to identify IV genome and molecularly characterized by 12 laboratories throughout Italy. A(H3N2) evolution was studied by conducting an in-depth phylogenetic analysis of the hemagglutinin (HA) gene sequences. The predicted vaccine efficacy (pVE) of vaccine strain against circulating A(H3N2) viruses was estimated using the sequence-based Pepitope model. Results: The overall IV-positive rate was 7.2% (894/12,393), all were IV type A. Almost all IV-A (846/894; 94.6%) were H3N2 that circulated in Italy with a clear epidemic trend, with 10% positivity rate threshold crossed for six consecutive weeks from week 2022-11 to week 2022-16. According to the phylogenetic analysis of a subset of A(H3N2) strains (n=161), the study HA sequences were distributed into five different genetic clusters, all of them belonging to the clade 3C.2a, sub-clade 3C.2a1 and the genetic subgroup 3C.2a1b.2a.2. The selective pressure analysis of A(H3N2) sequences showed evidence of diversifying selection particularly in the amino acid position 156. The comparison between the predicted amino acid sequence of the 2021-2022 vaccine strain (A/Cambodia/e0826360/2020) and the study strains revealed 65 mutations in 59 HA amino acid positions, including the substitution H156S and Y159N in antigenic site B, within major antigenic sites adjacent to the receptor-binding site, suggesting the presence of drifted strains. According to the sequence-based Pepitope model, antigenic site B was the dominant antigenic site and the p(VE) against circulating A(H3N2) viruses was estimated to be -28.9%. Discussion and conclusion: After a long period of very low IV activity since public health control measures have been introduced to face COVID-19 pandemic, along came A(H3N2) with a new phylogenetic makeup. Although the delayed 2021-2022 influenza season in Italy was characterized by a significant reduction of the width of the epidemic curve and in the intensity of the influenza activity compared to historical data, a marked genetic diversity of circulating A(H3N2) strains was observed. The identification of the H156S and Y159N substitutions within the main antigenic sites of the most of sequences also suggested the circulation of drifted variants with respect to the 2021-2022 vaccine strain. Molecular surveillance plays a critical role in the influenza surveillance architecture and it has to be strengthened also at local level to timely assess vaccine effectiveness and detect novel strains with potential impact on public health

Experimental and Numerical Analysis of the Hydrodynamics around a Vertical Cylinder in Waves

The present study provides an extensive analysis on the hydrodynamics induced by a vertical slender pile under wave action. The authors carried out the study both experimentally and numerically, thus enabling a deep understanding of the flow physics. The experiments took place at a wave flume of the Università Politecnica delle Marche. Two different experimental campaigns were performed: In the former one, a mobile bed model was realized with the aims to study both the scour process and the hydrodynamics around the cylinder; in the latter one, the seabed was rigid in order to make undisturbed optical measurements, providing a deeper analysis of the hydrodynamics. The numerical investigation was made by performing a direct numerical simulation. A second order numerical discretization, both in time and in space, was used to solve the Navier–Stokes equations while a volume of fluid (VOF) approach was adopted for tracking the free surface. The comparison between experimental and numerical results is provided in terms of velocity, pressure distributions around the cylinder, and total force on it. The analysis of the pressure gradient was used to evaluate the generation and evolution of vortices around the cylinder. Finally, the relation between scour and bed shear stresses due to the structure of the vortex pattern around the pile was assessed. It is worth noting that the physical understanding of this last analysis was enabled by the combined use of experimental data on scour and numerical data on the flow pattern

Water efficiency and economic assessment of domestic rainwater harvesting systems in buildings with one-to three-floor elevations

Abstract The focus of the paper is the evaluation of the performance of domestic rainwater harvesting (DRWH) systems in multi-family buildings with one- to three-floor elevations by means of a cost–benefit analysis. The rainwater is here used for both indoor and outdoor non-potable water consumption. The study was carried out with reference to different residential building typologies (flat and condominium) in a specific local climate condition (Ancona). The buildings are characterized by different rooftop areas (100–400 m2), building floor elevations (one to three floors) and inhabitant numbers (3–54 persons). Moreover, in order to highlight the role of the tank capacity on the performance of DRWH, its capacity was changed in the range 50–200%. The combinations of all these parameters led to 276 test cases. The technical performance is evaluated by means of the water saving and retention efficiencies. The economical assessment is provided by comparing the costs and the savings due to the replacement of the water supplied with the rainwater. It is found that the payback periods changed in the range 10–35 years for the site-specific variables such as local rainfall and water service tariff. Cost–benefit analysis can help the design of DRWH systems, with particular attention to the sizing of the tank

Analisi sperimentale di una spiaggia in presenza di un sistema di drenaggio

Il sistema di drenaggio delle spiagge (Beach Drainage System, BDS) è un’opera a basso impatto ambientale di ausilio alle tradizionali tecniche di difesa costiera. Esso favorisce l’assorbimento dei flussi di infiltrazione attraverso l’abbassamento artificiale del livello di saturazione all’interno spiaggia. Il dreno, installato al di sotto della linea di saturazione, interagisce con l’idrodinamica della zona di swash e modifica i processi morfodinamici promuovendo la stabilizzazione dei sedimenti che, in condizioni naturali, verrebbero trasportati verso largo nella fase di back-wash dell’onda. Un programma di prove sperimentali in larga scala è stato condotto presso il laboratorio Grosser WellenKanal (GWK) di Hannover, Germania, su un modello bidimensionale del sistema di drenaggio. L’obiettivo di tale ricerca è stato quello di comprendere l’influenza del drenaggio sui processi idrodinamici e morfodinamici nella zona di riva. Nel presente lavoro l’attenzione è focalizzata sugli aspetti idrodinamici. In particolare sono analizzate le variazioni della linea di staurazione in condizioni naturali (non drenate) e drenate, gli effetti del drenaggio sul set-up e sui flussi di ritorno

FLOW DYNAMICS OF WAVES PROPAGATING OVER DIFFERENT PERMEABLE BEDS

The analysis of the hydrodynamics over porous media is of interest for many coastal engineering applications as the wave propagation over permeable structures or gravel beaches. The study of a boundary layer evolving over permeable beds is important to a better understanding of the interactions between the flow over and inside the porous medium. An experimental study has been performed to analyze the dynamics produced when waves propagate over two kinds of permeable beds: spheres (regular permeability) and natural stones. For comparative purposes the same analysis has been extended to two rough beds made, respectively, by a single layer of spheres and natural stones. We here focus on the correlation between the wave energy reduction induced by a porous bed and the flow resistance. An experimental law for the prediction of the friction factor is found by using the log-fit method in analogy to that reported in Dixen et al. (2008) for rough beds. Moreover, inspection of the turbulent velocity components allows one to evaluate the bottom shear stress. The latter analysis has been performed for different permeable beds (regular and irregular beds). A good agreement between the bottom shear stress behavior and the wave height attenuation over rough and permeable beds (Corvaro et al. 2010 and Corvaro et al. 2014a) has been observed.</jats:p

GREEN ROOM An architectural and urban device for energy efficiency and environmental comfort.

The article presents a design experiment conducted within the research PNRR VITALITYbased on the issues of sustainability and the quality of living spaces. Considering the inno-vation opportunities expressed by the energy transition, also achieved through nature-based regenerative solutions, aimed at reducing consumption and CO2 emissions, themethodology leads to the conceptualisation of the multiscalar spatial device Green Room:a volumetric decrement action associated with vegetative infiltration applied to significantparts of buildings and open spaces in three sample areas of the Adriatic-Mediterranean re-gion. Starting from morphological, typological, and climatic data and managing computa-tional simulation processes, the experiment aims to update design tools at the architecturaland urban scale, establishing a relationship between indoor and outdoor spaces to achievebenefits for the environment and people’s well-being