Understanding the strengths and limitations of the modeling capacity of surface flooding in urbanized floodplains is of utmost importance as such events are becoming increasingly frequent and ...extreme. In this study, we assess two computational models against laboratory observations of surface urban flooding in a reduced‐scale physical model of idealized urban districts. Four urban layouts were considered, involving each three inlets and three outlets as well as a combination of three‐ and four‐branch crossroads together with open spaces. The first model (2D) solves the shallow‐water equations while the second one (3D) solves the Reynolds‐averaged Navier‐Stokes equations. Both models accurately predict the flow depths in the inlet branches. For the discharge partition between the outlets, deviations between the computations and laboratory observations remain close to the experimental uncertainties (maximum 2.5 percent‐points). The velocity fields computed in 3D generally match the measured surface velocity fields. In urban layouts involving mostly a network of streets, the depth‐averaged velocity fields computed by the 2D model agree remarkably well with those of the 3D model, with differences not exceeding 10%, despite the presence of helicoidal flow (revealed by the 3D computations). In configurations with large open areas, the 3D model captures generally well the trajectory and velocity distribution of main surface flow jet and recirculations; but the 2D model does not perform as well as it does in relatively channelized flow regions. Visual inspection of the jet trajectories computed by the 2D model in large open areas reveals that they substantially deviate from the observations.
Plain Language Summary
Advancing our modeling capacity of urban flooding is of utmost importance for improving the design of risk reduction measures. During extreme urban flooding, complex flow patterns develop in urban environments, involving three‐dimensional flow structures. Though, urban floods are commonly simulated with two‐dimensional computational models. So far, no detailed comparison between flow fields predicted by two‐ and three‐dimensional computational models were conducted and assessed against reference data such as experimental observations for representative configurations of urban flooding. In this study, we assess two computational models against laboratory observations of urban flooding in a reduced‐scale physical model of an idealized district.
Key Points
Predictions of 2D and 3D computational models were compared against laboratory experiments representing urban flooding in a steady‐state
Both models perform equally well to predict upstream flow depth, outlet discharge partition, and velocity field in street networks
In urban layouts with large open spaces, only the 3D model accurately predicts the velocity field
Highlights:
Graphic tools and virtual reconstruction applied to watermills contribute to their overall understanding as an anthropogenic landscape.
Virtual reconstruction of the milling mechanisms ...allows us to understand the mill operation beyond the mere construction preservation.
The Riamonte mills are an example of a group of canal mills linked to a single dam and with a social typology of inheriting turns to grind.
Abstract:
Each concello (municipality) in Galicia is home to a large number of pre-industrial rural heritage assets integrated into the landscape. Among them are the water mills, usually made up of small constructions that are difficult to reuse in their original function. They are not easily compatible with other uses either. Their current state of abandonment requires their cataloguing and correct valorization as pre-industrial archaeological heritage. These constructions must be conceived as interrelated constructive groupings, in their original physical and social context. A good example of this is the unpublished sample of the Riamonte milling complex. Its study, digitalization and virtual recreation by means of computer-assisted graphics have great potential for dissemination to the public and better integration into the nature trail near the riverbed. Graphically presenting archaeological heritage through virtual media helps to promote social understanding in order to raise awareness of the importance of its protection and irreplaceable nature, especially in case of those vestiges lacking sufficient security to survive. Due to the large amount of vegetation around the wall remains, a rigorous planimetric survey of the entire complex was carried out, followed by three-dimensional (3D) modelling of representative elements. In addition, applying a rigorous principle of transparency, a chromatic differentiation is made in the 2D and 3D virtual reconstructions between already existing and newly added elements. Regarding the 3D model, a historical-archaeological evidence scale is used, allowing a graphic identification of the authenticity degree required to provide reliability in the reconstruction of lost or altered parts. This facilitates virtual recreation interpretation among future researchers from different disciplines. The Riamonte mill complex is part of a typology typical of the region, in which the use of virtual models makes it possible to reach the scales of the territory, the building and the machinery, facilitating the correct understanding of this cultural heritage.
•Fragility curves for Italian RC precast industrial buildings were developed.•An analytical method using dynamic analyses in 2D and 3D environment was employed.•Beam–column connection failure was ...explicitly accounted for as collapse limit state.•Collapse fragility curves are dominated by connection failure mechanism.•Vertical input in dynamic analyses is critical for connection collapse evaluation.
Despite the moderate ground motions observed during the seismic events in Northern Italy, May 2012, reinforced concrete (RC) precast industrial buildings suffered excessive damage, which led to substantial direct and indirect losses. The aim of this paper is to present a seismic fragility model for Italian RC precast buildings, to be used in earthquake loss estimation and seismic risk assessment. An analytical methodology has been used that consists of (1) random sampling of one hundred structures for each building typology, (2) pushover analysis to establish a number of damage limit states, (3) execution of nonlinear dynamic analysis and comparison of the maximum demand with the limit state capacity to allocate the structure in a damage state, and (4) regression analysis on the cumulative percentage of buildings in each damage state for a set of intensity measure levels to derive the statistical parameters of the fragility functions. The building population employed in the analysis was generated considering both material and geometric variability that was obtained from the field surveys of 650 industrial facilities, as well as other information available in the literature. Several aspects of the fragility derivation process were further analysed, such as the correlation between different intensity measure types and damage, the consideration of different collapse mechanisms (e.g. beam–column connection failure) and the differences in the resulting fragility curves when adopting a 2D or a 3D modelling environment. A good agreement with preliminary empirical fragility functions based on field data was also observed.
•A novel 3D Eulerian porous medium model is developed for the gas–liquid flow in a RPB.•The sensitivity of the capillary pressure and mechanical dispersion models is analyzed.•The effect of liquid ...dispersion under different design and operational parameters are obtained.•The established model paves the way for simulating a 3D full scale RPB effectively and accurately.
Liquid dispersion is very important for the modelling of liquid flow in a rotating packed bed (RPB) when an Eulerian porous medium approach is employed. For investigating the effect of the liquid dispersion in a practical RPB, a 3D Eulerian porous medium model has been established coupled with the appropriate interfacial, drag and dispersion forces formulations. The sensitivity of the parameters employed in these formulations has been thoroughly analyzed. New forms of the porous resistance model and the effective interfacial area correlation have been developed for the non-uniform two-phase flows. The simulation results show that the effect of the capillary pressure and mechanical dispersion forces on the liquid flow distribution and holdup in the RPB is clear and important. In addition, the effects of the dispersion force on the liquid holdup under different design and operational parameters have been thoroughly analyzed and it is found that the effect of the dispersion forces on the liquid holdup is almost the same for different nozzle widths and the porosities of the packing investigated. The investigation demonstrates that utilizing the Eulerian method can substantially reduce the simulation time and efforts when compared to the pore resolved method, such as the Volume of Fluid method without loss in accuracy. This provides a feasible approach to simulate RPBs in full 3D and for RPB technology scaling up and optimizations.
The techniques of measuring and 3D modelling based on images, as is typical in photogrammetry, grew in interest again in recent years, since a new generation of software tools has spread. These ones ...implement in different measure the algorithms developed by computer vision, increasing the automation of the standard photogrammetric process. This made the use of image-based approaches for 3D models reconstruction enormously increase, which is an essential part of the Cultural Heritage documentation and analysis processes. Starting from these assumptions, the aim of the paper is to evaluate what and where it is possible nowadays to find the main differences between photogrammetry and computer vision approaches and how these have to be considered in the choice of the processing technique. The analysis has been performed starting from a theoretical point of view in order to trace the main characteristics of the two methods. Moreover, in order to complete the investigation, an experimental part is reported on two particular cases study, considered as representative of two types of usually surveyed objects. The results allow to enlighten some differences between the two image processing approaches, in terms of accuracy and achieved products.
•This work has demonstrated 3-dimensional geometrical modeling based on continuous energy for uranium nitride fuel with lead–bismuth cooled CANDLE reactor using MCNP6 code to analyst neutronic ...aspects.•The enriched plutonium compositions were set as initial fuel composition from LWR spent fuel at the upper zone without burnable poison to control the reactivity.•In Axial direction, the core was divided into 10 regions for tracking the burning wave and assessing neutronic performance.•Equilibrium state occurs after 30 years of operation and shows that the power fraction, nuclide densities and neutron flux distribution remain constant, and moving in axial direction.•Burning wave velocity can be calculated from the shifting of power peak position for several thermal power core designs, the burning wave velocity for 800 MWth, 600 MWth and 400 MWth thermal power are ∼ 2.5 cm/year, ∼1.56 cm/year and ∼ 1 cm/year respectively.•Fission products that occurred in equilibrium state can be predicted as an ideal CANDLE fuel composition and can be used as references for the next study.
The neutronic analysis of full-core 3-dimensional geometrical modeling for a CANDLE reactor was conducted in this study, utilizing uranium nitride fuel and the MCNP6 code based on continuous energy. The fuel core composition was sourced from advanced pressurized water reactor (APWR) spent fuel with a 5-year cooling time and 49 GWd/t of burnup. The burnable poison adjustment was omitted in this design, as theoretically, the CANDLE reactor can maintain criticality without control rods. To streamline the modeling process, the radial direction of the fuel core composition was homogeneously designed. Additionally, for tracking the burning wave and assessing neutronic performance, the axial direction was segmented into 10 regions, each with a 25-cm height. The total burnup calculation spanned 80 years, with the assumption of 10,000 neutron number histories per cycle, aimed at identifying the time required to reach equilibrium. This study also investigated the impact of thermal power variation on neutronic results within the same core geometry. It was observed that power distribution and nuclide number densities shifted with a constant shape in the axial direction. As a breeder reactor, the conversion ratio of the CANDLE reactor for various thermal powers exceeded unity, with higher thermal power facilitating faster equilibrium state attainment. Burning wave velocity was calculated by analyzing the shifting of power peak positions for different thermal power core designs, revealing velocities of approximately ∼ 2.5 cm/year, ∼1.56 cm/year, and ∼ 1 cm/year for thermal powers of 800 MWth, 600 MWth, and 400 MWth, respectively.
This paper studies the behavior of a transverse through defect in an ingot during complex vortex flow of metal deformed by the radial shift rolling (RSR) method. The aim of the work was to ...investigate the applicability of the RSR method for the deformation treatment of oxide-dispersed strengthened steel (ODS-steel) ingots into a final semi-finished product. Vortex flow of metal promotes dispersion of alloying solid oxides and refinement of steel structure. However, the question of development or closure of possible casting defects of ODS-steel ingot remains open. For this purpose, an ODS-steel ingot with a through-hole modelling the defect was rolled according to the assumed process scheme. Also, to visualize the evolution of the defect in more detail during the rolling process, a simulation of thesame defect development in an aluminum bar has been performed in 2 mm steps. The results of both rolls showed good correlation. Based on many cross-sections of the experimental bars, detailed 3D models of the defect evolution were built. An average reduction of 50 % in defect volume was found. Welding of the outer areas occurs immediately, but the central areas remain unclosed, stretching proportionally with the drawing of the rod during rolling. For this reason, RSR cannot be used with large cavity defects in the axial zone, but this method is guaranteed to weld surface defects even at low reductions.
•3D variable-density model to evaluate pumping impacts on a fresh groundwater lens.•Model calibration used hydraulics, groundwater salinity and geophysical data.•AEM was key to constraining modelled ...fresh groundwater lens geometry.
Saltwater intrusion is the greatest risk to coastal community water supplies where they are dependent on fresh groundwater as the main source of supply. For small, fractured bedrock island aquifers, the fresh groundwater lens dynamics and transition zone geometry are complex. This study investigated the impacts of projected increases in groundwater pumping on a fresh groundwater lens to evaluate changes to the lens geometry and localized up-coning from the deeper, more saline aquifers beneath a small bedrock island in the tropics. A combination of traditional hydrogeological datasets and an airborne electromagnetic survey were used to develop a three-dimensional density-dependent groundwater flow and solute transport model using the SEAWAT code. This investigation represents one of very few studies that have taken such an approach. The model was calibrated using observed groundwater hydraulic heads and chloride concentration data, and calculated chloride values based on bulk conductivity measurements determined from inverted geophysical data. A staged calibration approach was adopted, firstly assessing the time-average lens extent and geometry, and secondly considering the seasonal groundwater level response. In the calibration, the geophysical data helped constrain the lens geometry in the absence of hydraulic head and chloride data. The calibrated model was used to test scenarios where groundwater pumping rates were increased above the current demand of 452 m3 d−1, showing that the lens is likely to be stable, i.e., its available storage is not expected to contract excessively, for extraction rates of up to 3,000 m3 d−1. The combined use of geophysical data and a numerical modeling approach was advantageous in investigating the lens characteristics. It also demonstrated how these techniques can be used together to evaluate coastal water resources and to manage water supply risks for coastal communities. The study demonstrated that the freshwater lens can likely support the freshwater demands of the remote community, and is a preferred option compared with high-cost and more complicated options such as seawater desalination and managed aquifer recharge.
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