A Feature Tracking velocimetry technique applied to inclined negatively buoyant jets

We have applied a Feature Tracking Velocimetry (FTV) technique to measure displacements of particles on inclined negatively buoyant jets (INBJs), issuing from a circular sharp-edged orifice, in order to investigate, among the others, the symmetry properties of the velocity field on this phenomenon. Feature Tracking Velocimetry is less sensitive to the appearance and disappearance of particles and to high velocity gradients than classical Particle Image Velocimetry (PIV). The basic idea of Feature Tracking Velocimetry is to compare windows only where the motion detection may be successful, that is where there are high luminosity gradients. The Feature Tracking Velocimetry algorithm presented here is suitable in presence of different seeding densities, where other techniques produce significant errors, due to the non-homogeneous seeding at the boundary of a flow. The Feature Tracking Velocimetry algorithm has been tested on laboratory experiments regarding simple jets (SJs) and inclined negatively buoyant jets released from a sharp-edged orifice. We present here velocity statistics, from the first to the fourth order, to study, among the others, the differences between simple jets and inclined negatively buoyant jets, and to investigate how the increase in buoyancy affects the inclined negatively buoyant jet behavior. We remark that, to the best of authors’ knowledge, this is the first attempt to investigate velocity statistics of an order higher than the second on Inclined Negatively Buoyant Jets. Among the others quantities, the mean streamwise velocity decay and the integral Turbulent Kinetic Energy have been measured and analyzed, both along the jet axis and in the upper and lower region of the simple jets and inclined negatively buoyant jets, as well as the streamwise and spanwise velocity skewness and kurtosis evolution along the axis. Results show the role of buoyancy in modifying the inclined negatively buoyant jet features; moreover, it is highlighted that the asymmetry of inclined negatively buoyant jets cannot be considered only a far field feature of this phenomenon, as it arises very close to the release point

Water waves overtopping over barriers

A numerical and experimental analysis of the wave overtopping over emerged and submerged structures, is presented. An original model is used in order to simulate three-dimensional free surface flows. The model is based on the numerical solution of the motion equations expressed in an integral form in time-dependent curvilinear coordinates. A non-intrusive and continuous-in-space image analysis technique, which is able to properly identify the free surface even in very shallow waters or breaking waves, is adopted for the experimental tests. Numerical and experimental results are compared, for several wave and water depth conditions

A non-intrusive and continuous-in-space technique to investigate the wave transformation and breaking over a breakwater

To design longshore breakwaters, the evaluation of the wave motion transformations over the structures and of the energy they are able to absorb, dissipate and reflect is necessary. To characterize features and transformations of monochromatic wave trains above a breakwater, both submerged and emerged, we have designed and developed a non-intrusive and continuous-in-space technique, based on Image Analysis, and carried out an experimental campaign, in a laboratory flume equipped with a wave-maker, in order to test it. The investigation area was lighted with a light sheet and images were recorded by a video-camera. The working fluid was seeded with non buoyant particles to make it bright and clearly distinct from dark background and breakwater. The technique, that is based on a robust algorithm to identify the free surface, has showed to properly work also in prohibitive situations for traditional resistive probes (e.g., very shallow waters and/or breaking waves) and to be able to measure the free surface all over the investigation field in a non-intrusive way. Two kind of analysis were mainly performed, a statistical and a spectral one. The peculiarities of the measurement technique allowed to describe the whole wave transformation and to supply useful information for design purposes

Politik Kebudayaan Zuriat Kiyai Marogan Dalam Mempertahankan Nilai-Nilai Budaya Di Pulau Kemaro

Kajian ini membahas tentang kebijakan budaya keturunan Kiyai Marogan dalam menjaga nilai-nilai budaya Pulau Kemaro sebagai bentuk pencegahan kepada pemerintah kota palembang yang ingin membangun kawasan tersebut. Tulisan ini juga menguraikan terkait politik pembangunan oleh pemerintah kota palembang yang akan dilakukan di pulau kemaro. Penelitian ini bertujuan untuk 1. Untuk mengetahui bentuk politik keturunan Kiyai Marogan yang mempertahankan nilai-nilai budaya yang ada di Pulau Kemaro. 2. Mengkaji upaya Zuriat Kiyai Marogan dalam memelihara dan melestarikan budaya lokal Pulau Kemaro. Hasil .penelitian. ini menunjukkan bahwa keterlibatan zuriat kiyai marogan Dalam menjaga nilai budaya atau melestarikan kembali nilia-nilai kebudayaan di pulau kemaro supaya tidak terjadinya marjinalisasi pembangunan yang dilakukan oleh pemerintah kota palembang yang hanya memutuskan kebijakan sepihak tanpa adanya koordinasi dengan masyarakat setempat dan pemilik tanah, maka orientasi sikap politik dari zuriyat Ki Marogan menunjukkan upaya-upaya dalam mempertahankan kebudayaan dengan Suatu cara yang menekankan hubungan lintas budaya dengan maksud bahwa keberadaan satu budaya harus memperhitungkan keberadaan budaya lain. Hal ini memunculkan ide-ide seperti kesetaraan, toleransi dan saling menghormati. Hasil penelitian ini diharapkan dapat menjadi sumber informasi bagi mahasiswa khususnya program studi Politik Islam UIN Raden Fatah Palembang dan seluruh mahasiswa di Provinsi Sumatera Selatan

Figure apocalittiche dell'altrove buzzatiano

Si intende indagare il tema dell’altrove nella narrativa di Buzzati evidenziando il legame tra i testi dell’autore milanese e quelli appartenenti all’“apocalittica”, importante parte della letteratura biblica. In particolare si rintracceranno echi del linguaggio apocalittico nelle opere di Buzzati e si illustrerà lo sviluppo delle tematiche apocalittiche nella sua produzione narrativa

L’incanto agiografico nella produzione in volgare. Il caso delle Considerazioni sulle stimmate

This essay aims to highlight the peculiarity of the hagiographic texts, since they join their didactic  requirements with the pleasure of entertainment and narration. Moreover, these texts reveal an extraordinary  ability of transformation, so that the figure of the Saint appears to the reader as a present and existing figure.  In particular, emphasis is placed on the important transformation of textual hagiography in the transition  from Latin to the vernacular languages. In the Italian area, a special place is occupied by the unquestionable  leading figure of Saint Francis of Assisi and of those who dealt with the task of writing his biography. In the  second part of this contribution, there is a focus on the Considerazioni sulle stimmate (appendix to Fioretti  di San Francesco d’Assisi), whose writing has to be included within a precise path that was accomplished by  the Franciscan hagiography after the death of the founder. The descriptive power of the text and its  theological content are not diminished by the use of vernacular Italian: on the contrary, the “fascination” – this element typical of hagiographic discourse – is in many ways strengthened.Con tale contributo si intende sottolineare la peculiarità dei testi agiografici di unire le esigenze didattiche al  piacere della narrazione e dell’intrattenimento. Tali testi rivelano inoltre una straordinaria capacità di  trasformarsi, facendo sì che la figura del santo risulti sempre attuale per il pubblico destinatario. In  particolare si mettono in evidenza le importanti trasformazioni della testualità agiografica nel passaggio dal  latino alle lingue volgari: in area italiana, si registra in questa fase un indiscutibile protagonismo della figura  di Francesco d’Assisi e di coloro che si sono cimentati nella scrittura della sua biografia. Si pone dunque  attenzione, nella seconda parte del contributo, alle Considerazioni sulle stimmate (appendice dei Fioretti di  San Francesco d’Assisi), la cui stesura si inserisce all’interno di un preciso cammino compiuto  dall’agiografia francescana fin dalla morte del fondatore. La potenza espressiva del testo e il suo contenuto  teologico non vengono sminuite dall’utilizzo del volgare italiano, ma la componente di “incanto” propria del  discorso agiografico risulta al contrario rafforzata

May a standard VOF numerical simulation adequately complete spillway laboratory measurements in an operational context? The case of Sa Stria Dam

The present work aims to assess whether a standard numerical simulation (RANS-VOF model with k e closure) can adequately model experimental measurements obtained in a dam physical model. The investigation is carried out on the Sa Stria Dam, a roller compacted concrete gravity dam currently under construction in Southern Sardinia (Italy). The original project, for which a physical model was simulated, included a downstream secondary dam. However, due to both economic and technical reasons, the secondary dam may not be built. Hence, it is important to assess the flood discharge routing and energy dissipation in the modified plan. Numerical validation is performed adopting the same laboratory configuration, in presence of the downstream dam, and results show a good agreement with mean experimental variables (i.e., pressure, water level). An alternative configuration without the downstream dam is here numerically tested to understand the conditions of flood discharge and assess whether its results can give relevant information for the design of mitigation measures. The topic is of interest also from a more general perspective. Indeed, the feasibility to integrate numerical models with existing laboratory measurements can be very useful not only for new constructions but also for existing dams, which may need either maintenance or upgrading works, such as in case of flood discharge increment

Do Daily Activities Impact Gas Tamponade - Retina Contact after Pars Plana Vitrectomy? A Computational Fluid Dynamics Study

Purpose:To calculate the retinal surface alternatively in contact with gas and aqueous because of fluid sloshing during daily activities such as ocular saccade, turning the head, standing up, and being a passenger of a braking car.Methods:Fluid dynamics of aqueous and gas tamponade was reproduced using computational methods using the OpenFOAM open-source library. The double-fluid dynamics was simulated by the volume of fluid method and setting the contact angle at the aqueous-gas-retina interface.Results:Sloshing increased the retinal surface in contact with aqueous by 13% to 16% regardless of fill rate and standing up determined the largest area of wet retina, followed by car braking, head rotation, and ocular saccade (P < 0.001). All activities except the ocular saccade determined a significant increase in the surface of retina in contact with the aqueous (P < 0.005). Car braking induced the highest shear stress (6.06 Pa); standing up determined the highest specific impulse and saccade the lowest.Conclusion:Daily activities instantaneously reduce the amount of retina consistently in contact with gas tamponade and increase shear stress giving aqueous a potential access to the subretinal space regardless of patients' compliance

A meteo-hydrological forecasting chain: performance of the downscaling and rainfall-runoff steps in a small catchment

Forecasting ground effects of severe meteorological events with an adequate lead time is fundamental for civil protection scopes and is therefore an important challenge for the scientific community. The paper focuses on the performance of some steps of a meteo-hydrological forecasting chain that can be applied in small watersheds to assess hydrological risk deriving by an intense storm predicted at the large meteorological scale. The proposed procedure integrates large-scale rainfall fields, as those produced by numerical weather prediction (NWP) models, with statistical rainfall downscaling and hydrological modelling. More in details, assuming a large scale rain rate as the input of the process, the forecasting chain produces an ensemble of hydrographs that are post-processed in order to give a probabilistic representation of mean streamflow maxima for different time windows. The outcome of this procedure can be thus applied to assess the risk that some critical streamflow thresholds may be exceeded. The procedure has been tested on more than one thousand recorded events in the Araxisi catchment in Sardinia, Italy. Results and performances are presented and discussed