Massive Flow Research Articles

ESS-IoT: The Smart Waste Management System for General Household Shen Yuong Wong, Huashuo Han, Kin Meng Cheng, Ah Choo Koo and Salman Yussof

With the urban population’s growth, unethical and unmanaged waste disposal may negatively impact the environment. In many cities, a massive flow of people in municipal buildings or offices has generated vast amounts of waste daily, which correlates to the enormous expenses of waste management. The critical issue for better waste management is waste collection and sorting. In this study, the Electronic Smart Sorting- Internet of Things (ESS-IoT) is proposed to assist people in better waste management. The ESS-IoT system uses Raspberry Pi 4b as the microcontroller with three modules, and it is designed with two main functions: waste collection and waste classification. The two main functions have been deployed separately in the literature, while this study has combined both functions to achieve a more comprehensive smart bin waste disposal solution. Waste collection is triggered by the overflow alarm mechanism that employs ultrasonic and tracker sensors. On the other hand, the waste classification is implemented using two classification algorithms: Random Forest (RF) prediction model and Convolutional Neural Network (CNN) prediction model. An experiment is conducted to evaluate the accuracy of the two classification algorithms in classifying various types of waste. The waste materials under investigation can be classified into four categories: kitchen waste, recyclables, hazardous waste, and other waste. The results show that CNN is the better classification algorithm between the two. Future work proposes the research extension by introducing an incentive mechanism to motivate the household communities using a cloud-based competition platform incorporated with the ESS-IoT system.

Study on the new technologies that will boost hydrogen as a global energy vector

The emission of greenhouse gases (GHG) into the atmosphere represents a real problem and a great challenge for the following decades; the effects of climate change are already palpable: warmer temperatures, ocean and sea level rise as well increased frequency of high precipitations events. Further warming will inevitably occur in the decades to come-the question is whether it can be limited to two degree rise-and will place higher pressure on ecosystems and human populations, particularly those living in tropical areas. Middle and upper classes of emerging countries increased their CO2e emission more than any other group within the past 15 years. The new geography of global emitters calls for climate action in all countries.1 Based on our new global energy paradigm; the present work aims to carry out a study in the field for renewable energies, on the great potential that would take advantage of the use of hydrological resources available in the potential zones of the developing economies, on the production and use of Hydrogen as a clean energy vector like a promising source and sustainable economy in the coming years. Overpopulation, uncontrolled massive migratory flows and the current Codiv-19 pandemic, all this coincides and is presented in a timely manner; given the current energy situation, which is practically becoming unsustainable, due to the intense and irrational use of fossil fuel. Which as a consequence of this the entire planet is suffering the effects of global warming; which failure to reverse the situation will cause major environmental catastrophes in the short term. Hydrogen, the most abundant element of the universe since it is not free in nature, is necessary to produce it from hydrogenated substances, mainly water and hydrocarbons. The easy availability and abundance of the material from which hydrogen can be obtained, as well as the diversity of means to obtain it; provide a great potential as an energy alternative. This, coupled with the fact that the use of hydrogen only leaves water as the only residue; makes it very favorable to the environment, looking for ways to produce it only with renewable energy sources, such as solar, wind, hydraulic, among others. These characteristics will boost energy economy based abundant hydrogen.2 In order to have a clear and general idea of the research project to be carried out, it will begin with a study in different segments, given the extensive information required, it will begin as follows: Firstable an analysis of greenhouse gas emission globally; what countries lead the most greenhouse emission to the atmosphere. Second the new trends and research that involved the hydrogen in advanced economies. What recent technologies will drive the massive consumption of hydrogen globally? To respond this question, It will be investigated what countries that currently lead the use of hydrogen and which technologies currently are already demanding a significant consumption of hydrogen, then will be analyzed data collected from studies about this new energetic paradigm, and if there is a correlation between population growth, percentage of energy demand, geographical area and the technological services sector. Variables obtained will be graphed and analyzed; and finally some preliminary results will be reported in the present work

The Outcomes of Patients with Haemoglobin Disorders in Cyprus: A Joined Report of the Thalassaemia International Federation and the Nicosia and Paphos Thalassaemia Centres (State Health Services Organisation)

Haemoglobinopathies, including thalassaemias and sickle-cell syndromes, are demanding, lifelong conditions that pose a significant burden to patients, families, and healthcare systems. Despite the therapeutic advances and the resulting improvements in prognosis accomplished in past decades, these patients still face important challenges, including suboptimal access to quality care in areas with developing economies, changing epidemiology due to massive migration flows, an evolving clinical spectrum due to ageing in well-treated patients, and limited access to novel high-cost therapies. We herein describe the organization of healthcare services for haemoglobinopathies in Cyprus—with particular focus on beta-thalassaemia, the most prevalent condition in this region—along with selected patient outcomes. This report aims at underscoring the fact that nationally funded and well-coordinated prevention and care programmes for chronic and complex conditions, such as haemoglobinopathies, with active involvement from patient organizations lead to effective disease control and excellent outcomes in survival, quality of life, social adaptation, and public health savings, and allow timely and effective responses to emerging crises, such as the COVID-19 pandemic. The Cyprus paradigm could therefore serve as a blueprint for the organization or adaptation of haemoglobinopathy programs in other countries since these disorders are still widely occurring.

Experimental investigation of convective heat transfer performance and hydrodynamics of pulsating flow through the rectangular grooved channel

This study presents hydrodynamics and heat transfer of steady and pulsating flow in a rectangular grooved channel for the Reynolds number and pulsation frequency ranges of 2x103 ≤ Re ≤ 6.5x103 and 0 ≤ F ≤ 5 (Hz) respectively. The Particle Image Velocimetry (PIV) method is employed for hydrodynamic investigation. Streamlines, velocity vectors, and vorticity contours are drawn to reveal massive flow motions and flow patterns. Flow pulsation significantly empowers the penetration of mainstream into the groove section; however, pulsation frequency has an important effect on this phenomenon. Moreover, Reynolds stress and root mean square of the fluctuations are presented to document turbulence statistics. In the heat transfer experiments, the positive effects of the improvement of the groove mainstream interaction and an increase in the mixing are observed. Heat transfer enhancement and pressure drop trade-off are considered by calculating the thermal performance factor. Pulsating flow remarkably augments the heat transfer from the grooved channel. However, the enhancement ability of the pulsating flow strongly depends on its frequency, F, and the value of the Reynolds number. Pulsating flow is a more effective method in low Reynolds numbers.

Flood patterns in a catchment with mixed bedrock geology and a hilly landscape: identification of flashy runoff contributions during storm events

Abstract. With flash flood events having been repeatedly observed in Central and Western Europe in recent years, there is a growing interest in how catchment physiographic properties and hydrological conditions are eventually controlling rapid and concentrated hydrological responses. Here we focus on a set of two nested catchments in Luxembourg (Europe) that have been exposed in 2016 and 2018 to flash flood events and study their seasonal runoff time transfer distributions. Both catchments are of similar size (∼ 30 km2) and have analogous hydrological distance distributions, but their geological bedrock and landscape features are notably different. The upper catchment (KOE) is dominated by a low land area (38 % of the catchment is located less than 30 m above the river network) consisting of variegated marly bedrock (middle Keuper Km3) and moderately steep Luxembourg sandstone outcrops (lower Liassic Li2). The lower catchment (HM) has its drainage network deeply cut into the Luxembourg sandstone, with half of it being covered by marly plateaus (Lower Liassic Li3, located between 80 and 100 m above the river network) featuring heavy clay soil. Based on data generated from a dedicated hydro-meteorological monitoring network, we calculated for 40 rainfall–runoff events observed between August 2019 and July 2021 the corresponding net rainfall transfer time distributions (TTDs) from the hillslopes to the catchment outlet. We then compared the TTD properties and related them to the catchment's hydrological state and rainfall properties. We observed a marked seasonality in TTDs for both catchments. The KOE catchment reacts fastest during the winter period (December–February), while its response time is most delayed and spread out during periods of catchment recharging (October–November) and drying (March–May). The HM catchment exhibits similar TTDs during the mid-October to mid-April period, but they diverge markedly during the remaining part of the year, with opposite variations. During the mid-April to mid-October period, the average response time increases progressively in the KOE catchment. This behavior is in stark contrast to the HM catchment, where response times are significantly shorter (peak discharge delay time decreases by −70 % ± 28 %) and more concentrated (runoff volume occurring in 1 h increases by +48 % ± 87 %) during the mid-April to mid-October, in comparison to the extended winter period. This opposite seasonality leads us to consider different control factors of the runoff transfer processes in relation with the topographic and geological layout of the catchment areas. In the KOE catchment, we found the TTD to be essentially driven by onset and cessation of hydrological connectivity on the flat marly terrain – the latter operating like a variable contributing area in terms of deep soil storage dynamics (except for one summer event). The HM section exhibits contrasted TTDs throughout the year, suggesting threshold-dependent hydrological processes. More specifically, particularly quick runoff transfers seem to dominate under dry conditions (mid-April to mid-October). Correlation analyses compared to the literature on runoff generation on the one hand and our descriptive knowledge of the catchments on the other hand suggest multiple causes for the triggering of these rapid flows. The fractured marly plateaus, but also the hydrophobic forest litter forming during dry conditions on steep slopes, stand as our main hypotheses in this respect. Moreover, the absence of a riparian zone, preventing any dampening of (observed) abrupt and massive flows during extreme precipitation events, also seems to be a key feature of the rapid runoff transfer. For improving our understanding and forecasting capabilities in Luxembourg (and more broadly in the nearby regions of Germany, Belgium, and France with similar physiographic and climate conditions), we recommend further studies focusing on catchments with fractured bedrock and limited riparian zones. Special attention may equally be given to the hypothesized responses of hydrophobic soil surfaces on steep hillslopes and marly soils to heavy precipitation events occurring after extended dry spells.

Lithostratigraphy, geology and geochemistry of the Tertiary volcanic rocks on Svartenhuk Halvø and adjoining areas, West Greenland

The Palaeogene volcanic succession in the northern part of the Nuussuaq Basin in West Greenland comprises three formations: the Vaigat and Svartenhuk Formations of Paleocene age (61–58 Ma) and the Naqerloq Formation of Eocene age (57–54 Ma). In this study, we formalise and describe the volcanic stratigraphy on Svartenhuk Halvø and the areas with lavas that flowed across the basin boundary onto the adjoining basement areas in the north and east. The Vaigat Formation comprises three members. The Kakilisaat and Nerutusoq Members are of minor volume and consist of, respectively, crustally contaminated basalts and chemically enriched basalts with relatively high contents of incompatible trace elements. They are overlain by the voluminous Nunavik Member of tholeiitic picrites (MgO ≥12 wt%) and subordinate magnesian basalts. The oldest volcanic deposits are commonly foreset-bedded hyaloclastites, and the overlying subaerial lavas are mainly thin, grey, crumbling flows. Eruption sites were mainly within the basin, with depocentres in the south and hyaloclastite and lava transport directions towards the north. Thicknesses vary from up to at least 2000 m in the south to ≥380 m in the northernmost exposures close to 72°N. The Svartenhuk Formation comprises four members. The lowest, Kuugaartorfik Member, is up to 100 m thick and consists partly of quartzofeldspathic and partly volcanogenic sediments; it is restricted to northern Svartenhuk Halvø and the Innerit peninsula. The overlying volcanic Tunuarsuk, Nuuit and Skalø Members are voluminous and widespread, with a combined thickness of up to 1800 m. They consist of tholeiitic basalts with similar chemical compositions but with correlatable stratigraphic variation patterns. The Tunuarsuk Member consists of interspersed flow groups of thin, grey flows and massive, brown flows; the Nuuit Member comprises mainly massive brown flows, and the Skalø Member is dominated by light grey flows. The Svartenhuk Formation oversteps the Vaigat Formation on the basement in the north and east. In these distal areas the Tunuarsuk and Nuuit Members constitute the major volumes, and preserved thicknesses are up to 1400 m. In northern and eastern Svartenhuk Halvø and also farther to the north and east, foreset-bedded hyaloclastites indicate transport directions towards the north and possibly east from eruption sites within the basin. The Naqerloq Formation comprises one member, the Arfertuarsuk Member, consisting of flows of brown basalt with relatively enriched chemistry and a single trachyte flow. The member is only found in western Svartenhuk Halvø and on Skalø, where it conformably overlies the older lavas with up to 350 m thickness preserved after erosion. Dykes of all three formations are present. The distribution of dykes of the Naqerloq Formation suggests that this originally extended much farther east. Picrites and basalts of the Vaigat and Svartenhuk Formations are geochemically related; the picritic lavas represent erupted primitive magmas, whereas the basaltic lavas represent fractionated melts formed in deep magma chambers. The melts formed from a geochemically depleted but heterogeneous mantle; in addition melts from enriched sources were occasionally incorporated. The enriched basalts of the Naqerloq Formation arose from another mantle source. Low contents of V, Cu and Ni in some crustally contaminated lavas indicate that accumulation of these elements may be present at depth.

The Origin and Decline of Russian Economic Geography

Economic geography in Russia was shaped by German geographers or under their strong influence, although Germany itself was not a world leader in world geography. The secondary nature of Russian geography was especially acutely felt in theoretical terms and in the orientation of this science to the needs and orders of the state. After perestroika and the collapse of the USSR, geography ceased to be a monolithic front, but, unfortunately, it is struck by scientific inbring and a massive flow of fictitious and demonstrative works. The war in Ukraine and the associated international isolation is becoming a decisive factor in the extinction of Russian economic geography

Russia has Spread its Wings. Phenomenology of our Era Global Systematic Contradiction Development

The article reveals specific features of the present day stage in the global systematic contradiction ‘creditors – debtors’ development. The origin of its critical stage was depicted in the context of form variety in the total hybrid, informational war that was projected well in advance, thoroughly worked-out and unleashed in a mass way against Russia by overseas and over-oceans Anglo-Saxon political elites. Technologies of the present day informational wars were studied and tools of cynical manipulation of public opinion of people in their own countries used to obtain a mass support of any decisions made by their governments were described. The massive information flow is meant to form a smoke-screen, which could hide real goals and intentions of architects of global domination. Deliberately formulated lies aim at discrediting a previously chosen object in eyes of the global public. This object is a nominated institutional enemy. This object forms a barrier due to its natural being and it is absolutely unacceptable for a new idea, i.e. global dominating exalted by British political elite to the strategic imperative of this implicit, pressing demand. Strategic imperative has a direct meaning, it is an official doctrine presented in a solemn, high-society atmosphere by the head of the Ministry of Foreign Affairs of Great Britain in the London City. The implicit demand, forming the essence of strategic imperative arose, grew and was promoted by all possible ways. This demand makes today the essence of Anglo-Saxon elites’ interests, the essence of any form of overthrowing the enemy in the process of developing the global systematic social-economic antagonism ‘creditors-debtors’. Today contradiction of interests of social groups forming poles of this antagonism passed over to the stage of global systematic antagonism of our era and has reached its climax. To attain the longed-for goal of strategic imperative for all of us London is going to stick to a new approach in international relations, which will be based on three spheres: military force, economic security and more advanced global alliances. Strategy of British political elite was defined and declared in public. An open, unprecedented by its aims and attracted resources challenge was thrown down to institutional enemies. Russia has accepted the challenge. Today Russia is facing numerous most serious problems that must be settled without any doubts.

11.1: Invited Paper: Production‐Worthy Massive Parallel Transfer Technology for the Assembly of Micro‐LED Based Displays Makarem A. Hussein

In this work, the basis for high production, deterministic massive transfer process flow and equipment technology utilizing an electromagnetic force transfer head, are introduced and discussed. A fundamental requirement for using electromagnetic force is to include a paramagnetic material in the metallurgy of the micro-LED contacts.

Application of artificial step-pools in natural hazard mitigation

The step-pool is a representative riverbed structure that is highly effective in increasing flow resistance and dissipating flow energy. Well-designed artificial step-pools can control channel incision, improve riverbed stability, and further mitigate natural hazards. In this study, step-pools following the characteristics of natural step-pools in terms of their geomorphology and energy dissipation are designed and applied to mitigate channel incision and debris flow, in a small watershed where riverbed structures are poorly developed and landslides and massive debris flow have occurred frequently as a result of channel incision. The jamming ratio of the step-pools is mostly less than 6.0, and the SP values, i.e., the development degree of riverbed are over 0.1, and these values are increased significantly compared with the original values, guaranteeing the stability of the constructed steps. Field investigation indicated that the artificial step-pools experienced little adjustment and generally remained stable during the flood season. The constructed steps caused a decreasing trend in deposition downstream, and achieved the expected effects in natural hazard mitigation effects by reducing and transferring the debris flows to hyper-concentrated flows and eventually to normal flood flows. Therefore, the stable step-pools effectively suppressed massive sediment movements, with 69.3% of the loose sediment eroded from the water erosion zone being trapped in the step-pool reach, which promoted uplift of the channel bed. Numerical simulation of debris flows reveals that the maximum kinetic energy of debris flow was reduced by about 27 % with the artificial step-pools compared to the pre-construction condition. The scientific findings and practical applications concerning the use of artificial step-pools could provide guidance for natural hazard mitigation in mountainous areas at the small watershed scale.

Optimization of Metro Trains Operation Plans Based on Passenger Flow Data Analysis

Metro intelligent system produces massive passenger flow and traffic data every day, among which route, station, and operation data are important for optimizing the train operation scheme. We collect passenger flow information of Shenzhen metro, analyze the passenger flow pattern and its distribution characteristics based on the data warehouse of the Hadoop platform, and optimize the train operation scheme in this paper. Using dynamic passenger flow data, an optimization model with train departure and dwell time as decision variables and passenger waiting time, passenger ride time, train full load ratio, and train operation balance as objectives is developed. An improved parallel genetic algorithm (GA) incorporating a simulated annealing algorithm (SAA) and an optimal individual retention strategy is used to find the optimal result. To verify the usefulness of the method, simulation experiments are conducted on the optimization model and method using the real passenger flow and train operation data of Shenzhen metro, and the simulation results are compared with the original plan.

Ghost lineages can invalidate or even reverse findings regarding gene flow.

Introgression, endosymbiosis, and gene transfer, i.e., horizontal gene flow (HGF), are primordial sources of innovation in all domains of life. Our knowledge on HGF relies on detection methods that exploit some of its signatures left on extant genomes. One of them is the effect of HGF on branch lengths of constructed phylogenies. This signature has been formalized in statistical tests for HGF detection and used for example to detect massive adaptive gene flows in malaria vectors or to order evolutionary events involved in eukaryogenesis. However, these studies rely on the assumption that ghost lineages (all unsampled extant and extinct taxa) have little influence. We demonstrate here with simulations and data reanalysis that when considering the more realistic condition that unsampled taxa are legion compared to sampled ones, the conclusion of these studies become unfounded or even reversed. This illustrates the necessity to recognize the existence of ghosts in evolutionary studies.

A&B: AI and Block-Based TCAM Entries Replacement Scheme for Routers

With the ever-increasing deployment of 5G and IoT, the number of end-hosts/terminals is increasing rapidly, so that routers have to cache more and more forwarding entries to guarantee communication reachability of these terminals, which makes Ternary Content Addressable Memory (TCAM)-based routers keep expanding resource requirements. However, the design and implementation of large-capacity TCAM-based routers are faced with such challenges: difficult circuit design, high production cost and energy consumption, thereby posing an urgent requirement on a lightweight TCAM that can still maintain those massive communication connections. In this paper, we aim to design a lightweight router with small storage requirement while still retaining the original communication connection performance, which is not straightforward due to the following two challenges: First, under the condition of massive sequential flow data, it’s difficult to accurately and timely select the entries to cache for a small capacity TCAM. Second, given the strict prefix matching principle, how to efficiently insert the selected entries into TCAM is also challenging. To address these problems, we propose A&B: an AI-based Routing entry prediction strategy (AIR) and a Block-based entry Insertion Tactic (BIT). AIR can precisely select entries by conducting accurate entry predictions, which converts dynamic flow-based prediction into stable and parallelizable entry-based prediction by decoupling spatio-temporal characteristics. BIT optimizes entry insertion by isolating TCAM into several blocks, thus eliminating the time-consuming entry movements. The experiment results based on real backbone traffic show that our lightweight A&B achieves comparable performance compared to the traditional schemes by using only 1/8 TCAM storage.

Application of immersed boundary based turbulence wall modeling to the Ahmed body aerodynamics

This paper applies a recently developed immersed boundary-turbulence wall modeling approach to turbulent flows over a generic car geometry, known as the Ahmed body, under massive flow separation within a lattice Boltzmann solver. Although the immersed boundary method combined with hierarchical Cartesian grid offers high flexibility in automatic grid generation around complex geometries, the near-wall solution is significantly deteriorated compared to the body-fitted simulation, especially when coupled to wall models for turbulent flows at high Reynolds number. Enhanced wall treatments have been proposed in the literature and validated for attached flow configurations. In this work, the Ahmed body with a slant surface of angle 35° is considered where the flow separates massively over the slant surface and the vertical base. The large eddy simulation is performed with a Reynolds stress constraint near-wall. The eddy viscosity is computed dynamically by taking into account the actually resolved Reynolds stresses. It approaches the mixing length eddy viscosity in attached boundary layers and returns to the subgrid eddy viscosity in detached boundary layers. An explicit equilibrium wall model has also been proposed to accelerate the calculation. Comparison with the no-slip boundary condition on the separated surfaces shows that the near-wall treatments with the equilibrium wall model operate reasonably well on both attached and detached boundary layers.

VaclavSmilHow the World Really Works: A Scientist's Guide to Our Past, Present and FuturePenguin, 2022, 325 p., $28.00.

VaclavSmilHow the World Really Works: A Scientist's Guide to Our Past, Present and FuturePenguin, 2022, 325 p., $28.00.

Using the WEI+ index to evaluate water scarcity at highly regulated river basins with conjunctive uses of surface and groundwater resources.

This paper discusses the role and limitations of using WEI+ as a water resource management tool for highly regulated river basins, with a conjunctive use of surface and groundwater resources. By considering flow regulation by reservoirs and aquifer systems, seasonality of water availability and demand, returns from water uses and environmental flow requirements, WEI+ constitutes an improvement to existing quantitative water scarcity indexes. However, the computation of WEI+ in complex river basins systems requires detailed data on water availability and water allocation to various uses, which are hard to obtain from monitoring records. The paper describes how the combined use of hydrological and water allocation models can help to overcome data gaps in water accounting and contribute to an improved analysis of water scarcity in heterogeneous and intricate river basins. It also examines the information provided by WEI+ and by other widely used water scarcity indexes, such as the Water Stress Index and the Criticality Ratio, as well as discusses the ability of WEI+ to measure the performance of hydraulic systems, usually evaluated by parameters such as reliability, vulnerability, and resilience. The Tagus River transboundary basin was selected as case study due to massive flow regulation by multi-purpose reservoirs and significant seasonality of water availability and demand. Results show the benefits of using WEI+ to define levels of water scarcity, over other indexes. Within the Tagus River systems, high values of WEI+ are reached during the summer months in regions with intensive agriculture, denoting severe water stress conditions in most sub-basins. The analysis also reveals the strong dependence of Portugal, the downstream country, on flows from Spain, the upstream country.

The dynamic stall dilemma for vertical-axis wind turbines

Vertical-axis wind turbines (VAWT) are excellent candidates to complement traditional wind turbines and increase the total wind energy capacity. Development of VAWT has been hampered by their low efficiency and structural unreliability, which are related to the occurrence of dynamic stall. Dynamic stall consists of the formation, growth, and shedding of large-scale vortices, followed by massive flow separation. The vortex shedding is detrimental to the turbine's efficiency and causes significant load fluctuations that jeopardise the turbine's structural integrity. We present a comprehensive experimental characterisation of dynamic stall on a VAWT blade including time-resolved load and velocity field measurements. Particular attention is dedicated to the dilemma faced by VAWT to either operate at lower tip-speed ratios to maximise their peak aerodynamic performance but experience dynamic stall, or to avoid dynamic stall at the cost of reducing their peak performance. Based on the results, we map turbine operating conditions to one of three regimes: deep stall, light stall, and no stall. The light stall regime offers VAWT the best compromise in the dynamic stall dilemma as it yields positive tangential forces during the upwind and downwind rotation and reduces load transients by 75% compared to the deep stall regime.

Curvature-Sensitive Transition Model Application to Flow Around a Smooth Circular Cylinder

Abstract Transition modeling in complex flow situations including adverse pressure gradient, streamline curvature, and massive flow separation represents one of the key challenges in computational fluid dynamics that greatly affects the flow characteristics in many thermal and fluid sciences applications. Here, we report a comparative study that helps investigate the capability of the curvature-sensitive kT−kL−ω−v2 transition model against the original kT−kL−ω algorithm in predicting the flow behavior surrounding a smooth circular cylinder subjected to Reynolds numbers in the range from 3.9×103 to 3.6×106. A C-program that fully accounts for the model's four transport equations is particularly developed and coupled with the transient solver of ansysfluent. The present simulation enables accurate prediction of the distributions of skin-friction and pressure coefficients along with careful specification of the corresponding drag coefficients and angles of separation and transition. The simulation reveals insignificant variations in the bulk flow behaviors using either model in both sub- and critical flow regimes while a remarkable improvement in the supercritical drag result is achieved using the curvature-sensitive model.

Characterization Of Shock Buffet On A Supercritical 2D Airfoil In Transonic Flow

The transonic flow over the supercritical OAT15A airfoil is investigated experimentally. Using time-resolved focusing schlieren sequences, we extracted the temporal evolution of the chordwise shock location for a wide range of combinations of Mach number and angle of attack. Based on this data, we identified the conditions of pre-buffet, buffet onset, fully-established buffet, and buffet-offset behavior. Key parameters characterizing most pronounced buffet behavior are presented and quantified in terms of the shock amplitude, its variation over multiple buffet cycles, and the associated frequency of the periodic shock oscillation. Fully-established buffet is identified at a Mach number of 0.72 and angle of attack of 5 deg. It is demonstrated that these operating conditions are characterized by a quasi-sinusoidal shock oscillation at a distinct frequency of 113 Hz, in good agreement with previous studies. This analysis reveals that the harmonic shock oscillation spanning a range of about 16.5% of the airfoil chord is accompanied by a coupled large-scale variation of the global flow topology. Both instantaneous and mean velocity components in the chordwise and vertical directions are discussed for representative phases of the buffet cycle. Instantaneous vector fields of both components provide insight into the flow organization throughout the buffet cycle and allow to identify the streamwise distance traveled by the shock wave within a full cycle. We can thus precisely capture the state of the shock wave and quantify the evolution of the shock-induced separation and the size of the turbulent wake. Severe variations of the flow topology are induced by the large-scale upstream and downstream shock displacement. The results show that incidents of massive flow separation are observed for shock positions being close to the upstream limit, and more general, that the wake influence is more pronounced when induced by an upstream traveling shock wave. Phase-averaged velocity profiles at significant locations along the airfoil suction side complement this analysis. Characteristic sets of velocity profiles are discussed in detail that allow to uniquely describe the development of the flow in each phase of the buffet cycle. Detailed contours and profiles of both velocity and Reynolds shear stress contributions across the wake region highlight the strong downstream influence the shock-induced turbulent wake. Phases of severe flow separation result in reverse flow persisting until the trailing edge which further substantiates the induced momentum deficit.

Narratives of Historical Memory and Their Touristic Function: The Case of Sergei Loznitsa’s Austerlitz

Abstract This article discusses a documentary film, Austerlitz (2016), by the Ukrainian film director Sergei Loznitsa. The film shows massive flows of tourists visiting Sachsenhausen and Dachau concentration camps, therefore, it is interpreted through the prism of dark tourism. The article argues that by functioning as a piece of virtual dark tourism, Austerlitz is constructed as a re-enactment of a collision with places of death. By refusing to moralize or condemn bored concentration camp visitors, Loznitsa enables the viewer to understand how radical experiences of mass destruction and death are being recorded in tourism practices in today’s society. The French semiotician and philosopher Roland Barthes argues that death is most clearly perceived when it opens up as an act that has already taken place in the past, but at the same time will also take place in the future – this has been and this will be. The article concludes that exactly this is the effect of the documentary film Austerlitz. By showing crowds of visitors walking in the empty spaces of concentration camps, Loznitsa opens up a tragedy of mass destruction and death that has already taken place, but at the same time will also happen.