Journal articles: 'Simulate extended air showers'

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Sciutto, S. J. "Air showers, hadronic models, and muon production." EPJ Web of Conferences 210 (2019): 02007. http://dx.doi.org/10.1051/epjconf/201921002007.

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We report on a study about some characteristics of muon production during the development of extended air showers initiated by ultra-high-energy cosmic rays. Using simulations with the recent new version of the AIRES air shower simulation system, we analyze and discuss on the observed discrepancies between experimental measurements and simulated data.

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Stowell, P., S. Fargher, L. F. Thompson, A. M. Brown, and P. M. Chadwick. "Gadolinium loaded Cherenkov detectors for neutron monitoring in high energy air showers." Journal of Instrumentation 17, no. 02 (February 1, 2022): T02005. http://dx.doi.org/10.1088/1748-0221/17/02/t02005.

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Abstract Monitoring of high energy cosmic ray neutrons is of particular interest for cosmic ray water Cherenkov detectors as intense bundles of delayed neutrons have been found to arrive after the initial passage of a high energy air shower. In this paper we explore the possibility of building large-area high-energy neutron monitors using gadolinium-loaded Water Cherenkov Detectors (WCDs). GEANT4 simulations of photon production in WCDs are used to estimate the maximum detection efficiency for a hypothetical system. Requiring a series of neutron induced gamma ray flashes distributed over an extended period of time (up to 20 μs) was shown to be an effective way to discriminate high energy neutron interactions from other backgrounds. Results suggest that neutron detection efficiencies of 4–15% may be possible using a gadolinium-loaded detection system above 200 MeV. The magnitude of gadolinium loading was also shown to significantly modify the timing response of the simulated detector.

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Kendi Kohara, A., Erasmo Ferreira, and Takeshi Kodama. "pp interactions in extended air showers." EPJ Web of Conferences 99 (2015): 10002. http://dx.doi.org/10.1051/epjconf/20159910002.

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JAIN, AMBAR, PANKAJ JAIN, DOUGLAS W. MCKAY, and JOHN P. RALSTON. "GRAVITON ENHANCED UHE NEUTRINO CROSS-SECTIONS AND GIANT AIR SHOWERS." International Journal of Modern Physics A 17, no. 04 (February 10, 2002): 533–54. http://dx.doi.org/10.1142/s0217751x02005979.

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The origin of the highest energy cosmic ray showers is a long standing puzzle. In models where the neutrino–proton cross-section rises to typical hadronic values at energies above 1020 eV, the neutrino becomes a candidate for the primary that initiates these showers. Large extra dimension, low scale gravity models suggest just such a strong neutrino interaction possibility. This raises a further question: are the characteristics of observed showers consistent with a neutrino origin? We simulate neutrino induced showers and compare them to proton-induced showers and to data. The comparison includes the study of starting depth, profile with depth, lateral particle distribution at ground and muon lateral distribution at ground level. Our comparison applies to any model of a strongly interacting, neutral particle with an energy transfer per collision of order 10% similar to the neutrino model studied here. We find that for cross-sections above 20 mb there are regions of parameter space where the two types of showers are nearly indistinguishable. We conclude that the neutrino candidate hypothesis cannot presently be ruled out on the basis of shower characteristics.

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Conti, E., and G. Sartori. "Considerations on the radio emission from extended air showers." Journal of Cosmology and Astroparticle Physics 2016, no. 05 (May 19, 2016): 043. http://dx.doi.org/10.1088/1475-7516/2016/05/043.

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Liu, Wei, and Xuelei Chen. "Numerical simulation of radio signal from extended air showers." Research in Astronomy and Astrophysics 15, no. 5 (April 29, 2015): 623–45. http://dx.doi.org/10.1088/1674-4527/15/5/002.

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Bott-Bodenhausen, M., I. Holl, A. Kabelschacht, A. Karle, E. Lorenz, R. Maier, M. Merck, et al. "A new air Cherenkov counter concept for the observation of extended air showers." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 315, no. 1-3 (May 1992): 236–51. http://dx.doi.org/10.1016/0168-9002(92)90709-d.

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Arsene, Nicusor, Markus Roth, and Octavian Sima. "Restoration of azimuthal symmetry of muon densities in extended air showers." Astroparticle Physics 121 (September 2020): 102452. http://dx.doi.org/10.1016/j.astropartphys.2020.102452.

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Montanus, J. M. C. "An extended Heitler–Matthews model for the full hadronic cascade in cosmic air showers." Astroparticle Physics 59 (July 2014): 4–11. http://dx.doi.org/10.1016/j.astropartphys.2014.03.010.

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Garg, Diksha, Sameer Patel, Mary Hall Reno, Alexander Reustle, Yosui Akaike, Luis A. Anchordoqui, Douglas R. Bergman, et al. "Neutrino propagation in the Earth and emerging charged leptons with nuPyProp." Journal of Cosmology and Astroparticle Physics 2023, no. 01 (January 1, 2023): 041. http://dx.doi.org/10.1088/1475-7516/2023/01/041.

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Abstract Ultra-high-energy neutrinos serve as messengers of some of the highest energy astrophysical environments. Given that neutrinos are neutral and only interact via weak interactions, neutrinos can emerge from sources, traverse astronomical distances, and point back to their origins. Their weak interactions require large target volumes for neutrino detection. Using the Earth as a neutrino converter, terrestrial, sub-orbital, and satellite-based instruments are able to detect signals of neutrino-induced extensive air showers. In this paper, we describe the software code nuPyProp that simulates tau neutrino and muon neutrino interactions in the Earth and predicts the spectrum of the τ-leptons and muons that emerge. The nuPyProp outputs are lookup tables of charged lepton exit probabilities and energies that can be used directly or as inputs to the nuSpaceSim code designed to simulate optical and radio signals from extensive air showers induced by the emerging charged leptons. We describe the inputs to the code, demonstrate its flexibility and show selected results for τ-lepton and muon exit probabilities and energy distributions. The nuPyProp code is open source, available on github.

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BERCUCI, A., T. ANTONI, W. D. APEL, F. BADEA, K. BEKK, M. BERTAINA, H. BLÜMER, et al. "THE DETECTION OF THE HIGH-ENERGY EAS MUON COMPONENT WITH THE LST DETECTOR OF KASCADE-GRANDE." International Journal of Modern Physics A 20, no. 29 (November 20, 2005): 6781–83. http://dx.doi.org/10.1142/s0217751x05030065.

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A Limited Streamer Tube (LST) detector system has been installed at the KASCADE-Grande experiment to study the Extensive Air Showers (EAS) muon component above a threshold of 2.4 GeV. The extended area of 255 m2 of the LST and the fine granularity of detection enables a detailed study of the muon spatial distribution in the very central zone of the air shower. A dedicated, fractal based analysis has been developed to take advantage of the observables of this detector setup. The sensitivity on cosmic rays mass and energy discrimination has been verified, based on 1.5 years of data collection by the KASCADE experiment.

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Stefanik, Stanislav, and Dalibor Nosek. "Atmospheric monitoring using the Cherenkov Transparency Coefficient for the Cherenkov Telescope Array." EPJ Web of Conferences 197 (2019): 02010. http://dx.doi.org/10.1051/epjconf/201919702010.

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The future ground-based gamma-ray observatory, the Cherenkov Telescope Array (CTA) will require reliable monitoring of the atmosphere which is an inherent part of the detector. We discuss here the implementation of the extended method of the Cherenkov Transparency Coeffcient for the atmospheric calibration for the CTA. The method estimates the atmospheric transmission of Cherenkov light, relying on the measurement of the rates of cosmic ray-induced air showers that trigger different pairs of telescopes. We examine the performance of our approach utilizing Monte Carlo simulations assuming various atmospheric conditions and CTA observation configurations.

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Mathur, Rohit, Jia Xing, Robert Gilliam, Golam Sarwar, Christian Hogrefe, Jonathan Pleim, George Pouliot, et al. "Extending the Community Multiscale Air Quality (CMAQ) modeling system to hemispheric scales: overview of process considerations and initial applications." Atmospheric Chemistry and Physics 17, no. 20 (October 19, 2017): 12449–74. http://dx.doi.org/10.5194/acp-17-12449-2017.

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Abstract. The Community Multiscale Air Quality (CMAQ) modeling system is extended to simulate ozone, particulate matter, and related precursor distributions throughout the Northern Hemisphere. Modeled processes were examined and enhanced to suitably represent the extended space and timescales for such applications. Hemispheric-scale simulations with CMAQ and the Weather Research and Forecasting (WRF) model are performed for multiple years. Model capabilities for a range of applications including episodic long-range pollutant transport, long-term trends in air pollution across the Northern Hemisphere, and air pollution–climate interactions are evaluated through detailed comparison with available surface, aloft, and remotely sensed observations. The expansion of CMAQ to simulate the hemispheric scales provides a framework to examine interactions between atmospheric processes occurring on various spatial and temporal scales with physical, chemical, and dynamical consistency.

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Conti, Enrico, and Giorgio Sartori. "On the coherent emission of radio frequency radiation from high energy particle showers." International Journal of Modern Physics D 26, no. 08 (February 16, 2017): 1750083. http://dx.doi.org/10.1142/s0218271817500833.

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Extended Air Showers produced by cosmic rays impinging on the earth atmosphere irradiate radio frequency radiation through different mechanisms. Upon certain conditions, the emission has a coherent nature, with the consequence that the emitted power is not proportional to the energy of the primary cosmic rays, but to the energy squared. The effect was predicted in 1962 by Askaryan and it is nowadays experimentally well established and exploited for the detection of ultra high energy cosmic rays. In this paper, we discuss in detail the conditions for coherence, which in literature have been too often taken for granted, and calculate them analytically, finding a formulation which comprehends both the coherent and the incoherent emissions. We apply the result to the Cherenkov effect, obtaining the same conclusions derived by Askaryan, and to the geosynchrotron radiation.

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Bhatt, Apoorva, Paweł Malecki, and Dariusz Góra. "Shore Shadow Effect in Baikal." Universe 8, no. 7 (June 24, 2022): 347. http://dx.doi.org/10.3390/universe8070347.

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The measurement of the individual charged particles especially muons in an extended air shower (EAS) resulting from primary cosmic rays provides important distinguishing parameters to identify the chemical composition of the cosmic primary particles. For Neutrino Telescope experiments like Baikal-GVD, the estimation of underwater muon flux is of importance to study atmospheric muons. In this paper, a GEANT4-based simulation is presented to estimate the atmospheric muon flux underwater taking Baikal-GVD as an example. The location of the Baikal-GVD experiment at Lake Baikal provides a unique opportunity to study the passage of muons through its northern shore and the water. The muons arriving from the north direction will lose more energy as compared to those arriving from the south. An approximation for the northern shore is also simulated in the GEANT4 geometry and the results of the simulation are compared with the measurements from the NT-96 detector. The results of the simulations are consistent with the shore shadow observed in the measurements in the NT-96. This approach can also be used to propagate the muons from generators like CORSIKA through long distances in matter like water, ice, earth, etc. for simulations in such experiments.

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Desombre, Jonathan, Denis Morichon, and Mathieu Mory. "SIMULTANEOUS SURFACE AND SUBSURFACE AIR AND WATER FLOWS MODELLING IN THE SWASH ZONE." Coastal Engineering Proceedings 1, no. 33 (October 9, 2012): 56. http://dx.doi.org/10.9753/icce.v33.currents.56.

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This study presents the results of the numerical simulation of a bore-driven swash flow over a permeable coarse- grained beach, carried out using the THETIS code. This code, based on a VOF-RANS approach, was previously used to simulate the swash flow over an impermeable beach (Desombre et al. 2013). For the present study, the code is extended to account for infiltration and exfiltration into a permeable immobile beach using the Volume-Averaged momentum equation that solves simultaneously the surface and subsurface flows. The results are compared with a laboratory data set from an experiment performed in the swash facility of the University of Aberdeen (Steenhauer et al. 2011). Comparisons between measurements and model results show the ability of the model to simulate the main features of subsurface flow during an entire swash cycle.

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Fehérkuti, Anna, Gábor I. Veres, Ralf Ulrich, and Tanguy Pierog. "Feasibility Studies of Charge Exchange Measurements in pp Collisions at the LHC." Entropy 24, no. 9 (August 25, 2022): 1188. http://dx.doi.org/10.3390/e24091188.

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(1) Pions produced in the development of extended atmospheric cosmic ray air showers subsequently decay to muons. The measured yield of those muons is generally underestimated by current phenomenological models and event generators optimized for cosmic ray physics. The importance of those disagreements motivates the feasibility studies for testing these models at the Large Hadron Collider (LHC) energies, at the highest center-of-mass energies achievable in a laboratory. The interaction of a nucleus and a virtual pion created in a charge exchange reaction at the LHC is a similar process to those contributing to the development of air showers in case of cosmic rays. The crucial problem of such an analysis is the selection of charge exchange events with the highest possible efficiency and high purity from proton–proton collisions at the LHC. (2) For this we consider distributions of various measurable quantities given by event generators commonly used in cosmic ray physics. (3) We examine the expected distributions of energy deposited in different calorimeters of an LHC experiment. We consider the geometrical acceptance and energy resolution of the detectors at the Compact Muon Solenoid (CMS) experiment, as an example. We determine a working point cut from the various options for event selection, and compare signal and background predictions using different models for a representative simple observable, such as average transverse momentum or charge particle yield. (4) A set of event selection cuts along these considerations is proposed, with the aim of achieving optimal efficiency and purity.

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Bussières, Normand, and Raoul J. Granger. "Estimation of Water Temperature of Large Lakes in Cold Climate Regions during the Period of Strong Coupling between Water and Air Temperature Fluctuations." Journal of Atmospheric and Oceanic Technology 24, no. 2 (February 1, 2007): 285–96. http://dx.doi.org/10.1175/jtech1973.1.

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Abstract Near-surface bulk water temperature measured in large northern lakes during the warm season with buoys can be characterized by three components: a slowly varying seasonal-/climate-related trend, fluctuations at the time scale of weather perturbations, and rapid daily fluctuations. When thermal infrared data are used to estimate surface water temperature, an additional term relating the differences between the skin and bulk temperatures is implied. Buoy data in this work serve to demonstrate the existence of a period of strong signal coupling between fluctuations of water temperature and air temperature. The period of strong signal coupling does not extend beyond the date of maximum temperature in the water temperature trend. During this period, a simple linear transformation of air temperature fluctuations can be used to simulate the buoy water temperature fluctuations. Attempts to simulate water temperature fluctuations from air temperature alone are not possible beyond this period. Water temperature simulation error depends on the distance of the air temperature measurement from the buoy, ranging from ±1.1°C at 0 km to ±1.4°C at 40 km. The method developed with buoy data is applied to the combination of satellite thermal infrared and operationally measured air temperature data to simulate water temperatures. Through the use of satellite data, the water temperature simulations are extended beyond the period of strong coupling.

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Lauer, Robert J. "First results from HAWC: monitoring the TeV gamma-ray sky." Proceedings of the International Astronomical Union 10, S313 (September 2014): 70–75. http://dx.doi.org/10.1017/s1743921315001891.

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AbstractThe High Altitude Water Cherenkov (HAWC) Observatory is a wide-field gamma-ray detector sensitive to primary energies between 100 GeV and 100 TeV. The array is being built at an altitude of 4100 m a.s.l. on the Sierra Negra volcano near Puebla, Mexico. Data taking has already started while construction continues, with the completion projected for early 2015. The design is optimized to detect extended air showers induced by gamma rays that pass through the array and to reconstruct the directions and energies of the primary photons. With a duty cycle close to 100% and a daily coverage of ~8 sr of the sky, HAWC will perform a survey of TeV emissions from many different sources. The northern active galactic nuclei will be monitored for up to 6 hours each day, providing unprecedented light curve coverage at energies comparable to those of imaging air Cherenkov telescopes. HAWC has been in scientific operation with more than 100 detector modules since August 2013. Here we present a preliminary look at the first results and discuss the efforts to integrate HAWC in multi-wavelength studies of extragalactic jets.

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Chung, Myung Kyoon, Hyung Jin Sung, and Kye Bock Lee. "Computational Study of Turbulent Gas-Particle Flow in a Venturi." Journal of Fluids Engineering 108, no. 2 (June 1, 1986): 248–53. http://dx.doi.org/10.1115/1.3242571.

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A “two-fluid” model has been applied to predict turbulent dilute gas-particle flow through a Venturi tube. Bulk motion of particles is considered as a secondary fluid flow which exchanges mass and momentum with the primary conveying air stream. Closure of the time-averaged equations is achieved by modelling turbulent second-order correlations with an extended mixing-length theory. Proposed closure model is found to aptly simulate the dependency of the static pressure drop on the particle size, flow rate and the loading ratio.

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Kim, Young Jin, Dimitri Mavris, and Richard Fujimoto. "Time- and space-parallel simulation of air traffic networks." SIMULATION 95, no. 12 (March 18, 2019): 1213–28. http://dx.doi.org/10.1177/0037549719831358.

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Computer simulations are widely used to design and evaluate air traffic systems. A fast time simulation capability is essential to effectively explore the consequences of decisions in airspace design, air traffic management, and operations. A parallel simulation approach is proposed to accelerate fast time simulation of air traffic networks that exploits both temporal and spatial parallelisms. A time-parallel algorithm is first described that simulates different time intervals concurrently and uses a fix up computation that exploits the scheduled nature of commercial air traffic to address the problem of dependencies between time segments. The time-parallel algorithm is then extended with a space-parallel simulation approach using Time Warp to simulate each time segment in parallel thereby increasing the amount of parallelism that can be exploited. The time and space-parallel algorithms are evaluated using a simulation of the U.S. National Airspace System (NAS). Experimental data is presented demonstrating that this approach can achieve greater acceleration than what can be achieved by exploiting time-parallel or space-parallel simulation techniques alone.

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Taylor, S. A., K. Chen, and R. Mahajan. "Moisture Migration and Cracking in Plastic Quad Flat Packages (PQFPs)." Journal of Electronic Packaging 119, no. 2 (June 1, 1997): 85–88. http://dx.doi.org/10.1115/1.2792224.

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Moisture migration in PQFPs (plastic quad flat packages) was investigated analytically and experimentally. Coupons made of the molding compound material were exposed to humid air for an extended time to determine its equilibrium moisture composition as a function of environmental moisture level. An IR (infrared) heating test was designed to simulate the high-temperature heat reflow process when PQFPs are soldered on computer boards. The C-SAM (C-mode Scanning Acoustic Microscopy) technique was employed to measure the delaminated areas. All packages failed after IR heating when the moisture content in PQFPs was higher than 60 percent of the equilibrium composition.

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Tauzia, X., J. F. Hetet, P. Chesse, G. Crosshans, and L. Mouillard. "Computer aided study of the transient performances of a highly rated sequentially turbocharged marine diesel engine." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 212, no. 3 (May 1, 1998): 185–96. http://dx.doi.org/10.1243/0957650981536853.

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The sequential turbocharging technique described in this paper leads to an improvement in the operations of highly rated diesel engines, in particular at part loads (better air admission). However, transient phases such as a switch from one turbocharger to two turbochargers can be difficult, mainly because of the inertia of the turbochargers. In order to simulate the dynamics of turbocharged diesel engines, the SELENDIA software has been extended. When applied to two different engines (12 and 16 cylinders), the program shows good agreement with the experimental data. Moreover, the compressor surge has been investigated during faulty switch processes. The software has then been used for predictive studies to evaluate the possibility of adapting sequential turbocharging to a 20-cylinder engine and to calibrate the optimum switching conditions (air and gas valve opening timing).

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Homola, Piotr, Dmitriy Beznosko, Gopal Bhatta, Łukasz Bibrzycki, Michalina Borczyńska, Łukasz Bratek, Nikolay Budnev, et al. "Cosmic-Ray Extremely Distributed Observatory." Symmetry 12, no. 11 (November 5, 2020): 1835. http://dx.doi.org/10.3390/sym12111835.

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The Cosmic-Ray Extremely Distributed Observatory (CREDO) is a newly formed, global collaboration dedicated to observing and studying cosmic rays (CR) and cosmic-ray ensembles (CRE): groups of at least two CR with a common primary interaction vertex or the same parent particle. The CREDO program embraces testing known CR and CRE scenarios, and preparing to observe unexpected physics, it is also suitable for multi-messenger and multi-mission applications. Perfectly matched to CREDO capabilities, CRE could be formed both within classical models (e.g., as products of photon–photon interactions), and exotic scenarios (e.g., as results of decay of Super-Heavy Dark Matter particles). Their fronts might be significantly extended in space and time, and they might include cosmic rays of energies spanning the whole cosmic-ray energy spectrum, with a footprint composed of at least two extensive air showers with correlated arrival directions and arrival times. As the CRE are predominantly expected to be spread over large areas and, due to the expected wide energy range of the contributing particles, such a CRE detection might only be feasible when using all available cosmic-ray infrastructure collectively, i.e., as a globally extended network of detectors. Thus, with this review article, the CREDO Collaboration invites the astroparticle physics community to actively join or to contribute to the research dedicated to CRE and, in particular, to pool together cosmic-ray data to support specific CRE detection strategies.

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Góra, Dariusz. "Cosmic-Ray Extremely Distributed Observatory: Status and Perspectives." Universe 4, no. 11 (October 24, 2018): 111. http://dx.doi.org/10.3390/universe4110111.

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The Cosmic-Ray Extremely Distributed Observatory (CREDO) is a project dedicated to global studies of extremely extended cosmic-ray phenomena, the cosmic-ray ensembles (CRE), beyond the capabilities of existing detectors and observatories. Up to date, cosmic-ray research has been focused on detecting single air showers, while the search for ensembles of cosmic-rays, which may overspread a significant fraction of the Earth, is a scientific terra incognita. Instead of developing and commissioning a completely new global detector infrastructure, CREDO proposes approaching the global cosmic-ray analysis objectives with all types of available detectors, from professional to pocket size, merged into a worldwide network. With such a network it is possible to search for evidences of correlated cosmic-ray ensembles. One of the observables that can be investigated in CREDO is a number of spatially isolated events collected in a small time window which could shed light on fundamental physics issues. The CREDO mission and strategy requires active engagement of a large number of participants, also non-experts, who will contribute to the project by using common electronic devices (e.g., smartphones). In this note, the status and perspectives of the project are presented.

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Carrère, Matthieu, Luisa Arrabito, Johan Bregeon, David Parello, Philippe Langlois, and Georges Vasileiadis. "A C++ Cherenkov photons simulation in CORSIKA 8." EPJ Web of Conferences 251 (2021): 03011. http://dx.doi.org/10.1051/epjconf/202125103011.

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CORSIKA is a standard software for simulations of air showers induced by cosmic rays. It has been developed mainly in Fortran 77 continuously over the last thirty years. It has become very difficult to add new physics features to CORSIKA 7. CORSIKA 8 aims to be the future of the CORSIKA project. It is a framework in C++17 which uses modern concepts in object oriented programming for an efficient modularity and flexibility. The CORSIKA 8 project aims to attain high performance by exploiting techniques such as vectorization, gpu/cpu parallelization, extended use of static polymorphism and the most precise physical models available. In this paper, we focus on the Cherenkov photon propagation module of CORSIKA, which is of particular interest for gamma-ray experiments, like the Cherenkov Telescope Array. First, we present the optimizations that we have applied to the Cherenkov module thanks to the results of detailed profiling using performance counters. Then, we report our preliminary work to develop the Cherenkov Module in the CORSIKA 8 framework. Finally, we will demonstrate the first performance comparison with the current CORSIKA software as well as physics validation.

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Theobald, Mark R., David Simpson, and Massimo Vieno. "Improving the spatial resolution of air-quality modelling at a European scale – development and evaluation of the Air Quality Re-gridder Model (AQR v1.1)." Geoscientific Model Development 9, no. 12 (December 16, 2016): 4475–89. http://dx.doi.org/10.5194/gmd-9-4475-2016.

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Abstract. Currently, atmospheric chemistry and transport models (ACTMs) used to assess impacts of air quality, applied at a European scale, lack the spatial resolution necessary to simulate fine-scale spatial variability. This spatial variability is especially important for assessing the impacts to human health or ecosystems of short-lived pollutants, such as nitrogen dioxide (NO2) or ammonia (NH3). In order to simulate this spatial variability, the Air Quality Re-gridder (AQR) model has been developed to estimate the spatial distributions (at a spatial resolution of 1 × 1 km2) of annual mean atmospheric concentrations within the grid squares of an ACTM (in this case with a spatial resolution of 50 × 50 km2). This is done as a post-processing step by combining the coarse-resolution ACTM concentrations with high-spatial-resolution emission data and simple parameterisations of atmospheric dispersion. The AQR model was tested for two European sub-domains (the Netherlands and central Scotland) and evaluated using NO2 and NH3 concentration data from monitoring networks within each domain. A statistical comparison of the performance of the two models shows that AQR gives a substantial improvement on the predictions of the ACTM, reducing both mean model error (from 61 to 41 % for NO2 and from 42 to 27 % for NH3) and increasing the spatial correlation (r) with the measured concentrations (from 0.0 to 0.39 for NO2 and from 0.74 to 0.84 for NH3). This improvement was greatest for monitoring locations close to pollutant sources. Although the model ideally requires high-spatial-resolution emission data, which are not available for the whole of Europe, the use of a Europe-wide emission dataset with a lower spatial resolution also gave an improvement on the ACTM predictions for the two test domains. The AQR model provides an easy-to-use and robust method to estimate sub-grid variability that can potentially be extended to different timescales and pollutants.

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Rode, C., D. Zukowska, and J. Kolarik. "IEA EBC Annex 68 – Consequences on ventilation and hygrothermal operation of buildings." Journal of Physics: Conference Series 2069, no. 1 (November 1, 2021): 012184. http://dx.doi.org/10.1088/1742-6596/2069/1/012184.

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Abstract The objective of the IEA EBC Annex 68 Project, “Indoor Air Quality Design and Control in Low Energy Residential Buildings”, has been to develop the fundamental basis for optimal design and control strategies for good Indoor Air Quality (IAQ) in highly energy efficient residential buildings. Focus has been on emission of chemical pollutants from building products and use of ventilation to alleviate IAQ effects. The question has been whether new paradigms for demand control should be developed based on knowledge from this project. The paper gives an overview of the project’s activities with regards to: - Gathering of laboratory and field data on pollution sources in buildings. - Formulation of a so-called “similarity approach” to predict emissions of volatile organic compounds based on knowledge from moisture transfer properties. - Gathering of a set of contemporary models to simulate the combined heat, air, moisture and pollution conditions of buildings and their assemblies. Based on this background, the project has identified and described an extended set of amenable ways to optimize the provision of ventilation and air-conditioning and to assess possibilities to bring this knowledge into practice. The paper gives an overview of the suggested solutions and their conditions.

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Cacabelos-Reyes, Antón, José Luis López-González, Arturo González-Gil, Lara Febrero-Garrido, Pablo Eguía-Oller, and Enrique Granada-Álvarez. "Assessing the Energy Demand Reduction in a Surgical Suite by Optimizing the HVAC Operation During Off-Use Periods." Applied Sciences 10, no. 7 (March 25, 2020): 2233. http://dx.doi.org/10.3390/app10072233.

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Hospital surgical suites are high consumers of energy due to the strict indoor air quality (IAQ) conditions. However, by varying the ventilation strategies, the potential for energy savings is great, particularly during periods without activity. In addition, there is no international consensus on the ventilation and hygrothermal requirements for surgical areas. In this work, a dynamic energy model of a surgical suite of a Spanish hospital is developed. This energy model is calibrated and validated with experimental data collected during real operation. The model is used to simulate the yearly energy performance of the surgical suite under different ventilation scenarios. The common issue in the studied ventilation strategies is that the hygrothermal conditions ranges are extended during off-use hours. The maximum savings obtained are around 70% of the energy demand without compromising the safety and health of patients and medical staff, as the study complies with current heating, ventilation and air conditioning (HVAC) regulations.

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Domfeh, Martin Kyereh, Samuel Gyamfi, Mark Amo-Boateng, Robert Andoh, Eric Antwi Ofosu, and Gavin Tabor. "Numerical Simulation of an Air-Core Vortex and Its Suppression at an Intake Using OpenFOAM." Fluids 5, no. 4 (November 26, 2020): 221. http://dx.doi.org/10.3390/fluids5040221.

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A common challenge faced by engineers in the hydraulic industry is the formation of free surface vortices at pump and power intakes. This undesirable phenomenon which sometimes entrains air could result in several operational problems: noise, vibration, cavitation, surging, structural damage to turbines and pumps, energy losses, efficiency losses, etc. This paper investigates the numerical simulation of an experimentally observed air-core vortex at an intake using the LTSInterFoam solver in OpenFOAM. The solver uses local time-stepping integration. In simulating the air-core vortex, the standard k − ε, realizable k − ε, renormalization group (RNG) k − ε and the shear stress transport (SST) k − ω models were used. The free surface was modelled using the volume of fluid (VOF) model. The simulation was validated using a set of analytical models and experimental data. The SST k − ω model provided the best results compared to the other turbulence models. The study was extended to simulate the effect of installing an anti-vortex device on the formation of a free surface vortex. The LTSInterFoam solver proved to be a reliable solver for the steady state simulation of a free surface vortex in OpenFOAM.

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Host, George E., Harlan W. Stech, Kathryn E. Lenz, Kyle Roskoski, and Richard Mather. "Forest patch modeling: using high performance computing to simulate aboveground interactions among individual trees." Functional Plant Biology 35, no. 10 (2008): 976. http://dx.doi.org/10.1071/fp08075.

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Functional–structural plant models (FSPMs) typically integrate suites of detailed physiological and phenological processes to simulate the growth of individual plants. Recent advances in high-performance computing have allowed FSPMs to be extended to patches of interacting trees. Here, we describe a parallel modelling strategy to run simultaneous individual tree models across an 8 × 8 patch of trees. The 64 ‘core’ trees are surrounded by multiple rings of neighbour trees to remove edge effects. A sensitivity analysis of the patch model demonstrates that computational factors such as the number of independently simulated trees (9 v. 36) or number of neighbour rings (3 v. 6) did not significantly influence model estimates of tree volume growth. Updated submodels for phenology and redistribution of overwinter carbohydrate storage allow the simulation to be more responsive to above ground competition among trees in a patch over multiple growing seasons. An 8-year patch-scale simulation of aspen clones 216 and 259 was conducted using high-resolution environmental data from the Aspen FACE Experiment, a long-term free-air carbon dioxide enrichment (FACE) study. Tree heights and volumes were comparable to 8-year growth measurements made at the Aspen FACE site.

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Liu, Cheng, Ruoqing Gao, and Changhong Hu. "A consistent mass–momentum flux computation method for the simulation of plunging jet." Physics of Fluids 34, no. 3 (March 2022): 032114. http://dx.doi.org/10.1063/5.0084894.

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In the present study, a robust and conservative numerical scheme is proposed to simulate the violent two-phase flows with high-density ratios. In this method, the mass conservation equation and the momentum equation are solved in a consistent manner. The tangent of hyperbola for interface capturing scheme is extended for the computation of the mass flux by which the sharpness and conservation property of density field is preserved. Compared with other recently proposed methods, no geometrical computation is involved in deriving the mass flux and the spurious velocity in the interfacial region can be completely avoided. To improve the computational efficiency, the present method is implemented on a parallel block-structured adaptive mesh refinement method with a staggered layout of variables. High-fidelity numerical simulation of plunging jet through the liquid surface is performed. A bubble detection algorithm is developed to track bubbles generated in air entrainment process. The evolution of the bubble cloud, air concentration, bubble-size, and bubble-velocity distributions are predicted and compared quantitatively with the experiment. Numerical results show the air entrainment and penetration depth are highly correlated with the upstream disturbance. The growing interfacial roughness of the jet yields more entrained air in the final stage of jet impingement. It is found that when the initial perturbation is introduced, the overall size of the equivalent bubble radius will expand, and the penetration depth of the bubble cloud will decrease, while a larger volume of air is entrained.

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Sorrentino, Marco, and Alena Trifirò. "Model-Based Diagnosis of Telecommunication Cooling Systems Malfunctioning." E3S Web of Conferences 238 (2021): 10003. http://dx.doi.org/10.1051/e3sconf/202123810003.

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A model is developed that allows simulating the most-likely failures possibly occurring in freecooling (FC) systems of telecommunication (TLC) switching rooms. Main aim is to provide an effective and online implementable diagnosis method, which in turn will allow fulfilling the threefold function of safeguarding electronic equipment, ensuring desired air quality in case of human presence and reducing malfunction-related waste of energy. Specifically in this work, obstruction (reduction of the volumetric flow of air introduced into the room) and loss of efficiency (degradation of the fan) are deepened. Two black-box sub-models were developed to simulate the above described faulty functioning of the free-coolers. Subsequently, the fault signature matrix was developed, through which the “symptoms”, calculated as residuals between the “faulty” and “non faulty” conditions of the monitored variables, are associated to the corresponding faults. The peculiarity of the telecommunication sector, where nowadays data acquisition and monitoring platforms are significantly spreading to monitor most significant energy consumptions, including cooling loads, was proved essential in guaranteeing effective isolation of different faults. The simulation results highlight the reliability of the developed diagnostic tool, expected to be versatile and easy to implement enough for being extended to air-handling unit diagnosis, as well as other industrial sectors.

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Wang, Xiaoshuai, Mengbing Cao, Feiyue Hu, Qianying Yi, Thomas Amon, David Janke, Tian Xie, Guoqiang Zhang, and Kaiying Wang. "Effect of Fans’ Placement on the Indoor Thermal Environment of Typical Tunnel-Ventilated Multi-Floor Pig Buildings Using Numerical Simulation." Agriculture 12, no. 6 (June 20, 2022): 891. http://dx.doi.org/10.3390/agriculture12060891.

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An increasing number of large pig farms are being built in multi-floor pig buildings (MFPBs) in China. Currently, the ventilation system of MFPB varies greatly and lacks common standards. This work aims to compare the ventilation performance of three popular MFPB types with different placement of fans using the Computational Fluid Dynamics (CFD) technique. After being validated with field-measured data, the CFD models were extended to simulate the air velocity, air temperature, humidity, and effective temperature of the three MFPBs. The simulation results showed that the ventilation rate of the building with outflowing openings in the endwall and fans installed on the top of the shaft was approximately 25% less than the two buildings with fans installed on each floor. The ventilation rate of each floor increased from the first to the top floor for both buildings with a shaft, while no significant difference was observed in the building without a shaft. Increasing the shaft’s width could mitigate the variation in the ventilation rate of each floor. The effective temperature distribution at the animal level was consistent with the air velocity distribution. Therefore, in terms of the indoor environmental condition, the fans were recommended to be installed separately on each floor.

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Magaritz-Ronen, L., M. Pinsky, and A. Khain. "Drizzle formation in stratocumulus clouds: effects of turbulent mixing." Atmospheric Chemistry and Physics Discussions 15, no. 17 (September 7, 2015): 24131–77. http://dx.doi.org/10.5194/acpd-15-24131-2015.

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Abstract. The mechanism of drizzle formation in shallow stratocumulus clouds and the effect of turbulent mixing on this process are investigated. A Lagrangian-Eularian model of the cloud-topped boundary layer is used to simulate the cloud measured during flight RF07 of the DYCOMS-II field experiment. The model contains ~ 2000 air parcels that are advected in a turbulence-like velocity field. In the model all microphysical processes are described for each Lagrangian air volume, and turbulent mixing between the parcels is also taken into account. It was found that the first large drops form in air volumes that are closest to adiabatic and characterized by high humidity, extended residence near cloud top, and maximum values of liquid water content, allowing the formation of drops as a result of efficient collisions. The first large drops form near cloud top and initiate drizzle formation in the cloud. Drizzle is developed only when turbulent mixing of parcels is included in the model. Without mixing, the cloud structure is extremely inhomogeneous and the few large drops that do form in the cloud evaporate during their sedimentation. It was found that turbulent mixing can delay the process of drizzle initiation but is essential for the further development of drizzle in the cloud.

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Magaritz-Ronen, L., M. Pinsky, and A. Khain. "Drizzle formation in stratocumulus clouds: effects of turbulent mixing." Atmospheric Chemistry and Physics 16, no. 3 (February 17, 2016): 1849–62. http://dx.doi.org/10.5194/acp-16-1849-2016.

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Abstract. The mechanism of drizzle formation in shallow stratocumulus clouds and the effect of turbulent mixing on this process are investigated. A Lagrangian–Eularian model of the cloud-topped boundary layer is used to simulate the cloud measured during flight RF07 of the DYCOMS-II field experiment. The model contains ~ 2000 air parcels that are advected in a turbulence-like velocity field. In the model all microphysical processes are described for each Lagrangian air volume, and turbulent mixing between the parcels is also taken into account. It was found that the first large drops form in air volumes that are closest to adiabatic and characterized by high humidity, extended residence near cloud top, and maximum values of liquid water content, allowing the formation of drops as a result of efficient collisions. The first large drops form near cloud top and initiate drizzle formation in the cloud. Drizzle is developed only when turbulent mixing of parcels is included in the model. Without mixing, the cloud structure is extremely inhomogeneous and the few large drops that do form in the cloud evaporate during their sedimentation. It was found that turbulent mixing can delay the process of drizzle initiation but is essential for the further development of drizzle in the cloud.

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Abbas, Eman, and Alaa H. Al-zuhairi. "Extended Finite Element Analysis of Reinforced Concrete Beams Using Meso-Scale Modeling." Association of Arab Universities Journal of Engineering Sciences 27, no. 1 (March 31, 2020): 19–29. http://dx.doi.org/10.33261/jaaru.2019.27.1.003.

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Four simply supported reinforced concrete (RC) beams were test experimentaly and analyzed using the extended finite element method (XFEM). This method is used to treat the discontinuities resulting from the fracture process and crack propagation in that occur in concrete. The Meso-Scale Approach (MSA) used to model concrete as a heterogenous material consists of a three-phasic material (coarse aggregate, mortar, and air voids in the cement paste). The coarse aggregate that was used in the casting of these beams rounded and crashed aggregate shape with maximum size of 20 mm. The compressive strength used in these beams is equal to 17 MPa and 34 MPa, respectively. These RC beams are designed to fail due to flexure when subjected to load as a two-point loading. To model the coarse aggregate realistically, the aggregate must distributed randomly according to the gradient and amount actually used in the mix design. This property is not found in the ABAQUS program that resulted in the use of an alternate program to represent the aggregate randomly. Next, the random representation of the aggregate were transfered to the ABAQUS program by using commands and instructions that the program can understand, to draw as a sketch. The comparison between experimental and numerical results showed that the XFEM is a good method used to simulate the non-smooth behavior in RC beams such as discontinuitiy and singularity. While a mesoscale model can be simulated the non-homogeneity in the concrete.

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Andreozzi, Assunta, Bernardo Buonomo, Oronzio Manca, and Sergio Nardini. "Natural Convection in Vertical Channels with Porous Media and Adiabatic Extensions." Defect and Diffusion Forum 297-301 (April 2010): 1432–38. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.1432.

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A numerical investigation on natural convection in air in a vertical heated channel, partially filled with porous medium, with adiabatic extensions downward and collinear the heated plates is accomplished. The fluid flow is assumed two-dimensional, laminar, steady state and incompressible. The porous material is considered as homogeneous and isotropic and the Brinkman-Forchheimer-extended Darcy model is considered. A finite-extension computational domain is employed to simulate the free-stream condition and allows to account for the diffusive effects and the numerical results are obtained using the finite volume method by FLUENT. Results in terms of wall temperature profiles are presented to evaluate the effects of the main thermal and geometrical parameters. The adiabatic extensions determine a wall temperature decrease and wall temperature decreases increasing Darcy number. In full filled heated channels wall temperature presents a significant increase for Darcy number decrease.

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Liu, Qingsheng, Jie Ouyang, Zhijun Liu, and Wuming Li. "Visualization and simulation of filling process of simultaneous co-injection molding based on level set method." Journal of Polymer Engineering 35, no. 9 (November 1, 2015): 813–27. http://dx.doi.org/10.1515/polyeng-2014-0339.

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Abstract Co-injection molding (CIM) is an advanced technology which was developed to meet quality requirements and to reduce the material cost. Theoretical investigations concerning it are very limited, especially for simultaneous CIM. The interactions of air, skin and core polymer melt in the process are very complex, which makes it more challenging to simulate free surface flows in the mold. Thus, this article presents a mathematical model for it. The extended Pom-Pom (XPP) model is selected to predict the viscoelastic behavior of polymer melt. The free surface is captured by the level set method. The article vividly shows the simultaneous CIM process by means of a visual numerical simulation technique. Both two-dimensional (2D) and 3D examples are presented to validate the model and illustrate its capabilities. The 3D flow behaviors of simultaneous CIM process are hard to predict numerically. To our knowledge, this is the first attempt at simulating melt flow behaviors in 3D simultaneous CIM based on the XPP constitutive equation and visual technique. The numerical results are in good agreement with the available experiment results, which establish the capability of the multiphase flow model presented in this article to simulate the flow behaviors of polymer melt in simultaneous CIM process.

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Wang, Xin, and Yong Fu Liang. "Effects of Concrete Pavement on Atmospheric Thermal Environment Adjacent to Ground under Solar Radiation." Applied Mechanics and Materials 744-746 (March 2015): 1390–93. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.1390.

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A numerical simulation has been conducted for concrete pavement on atmospheric thermal environment adjacent to ground under solar radiation. By computational fluent dynamics software Fluent, the finite volume method was used, and the solar radiation was described by the non-gray radiation transfer model and was solved by the Discrete Ordinate Method (DOM). The concept of constant temperature layer was introduced in order to determine the real temperature on pavement. Computed results indicate that the temperature on concrete pavement is impacted by the solar radiation significantly, and the atmospheric temperature falls down in geometric series with the increasing distance to ground. However, the effects of pavement on the temperature of ambient air beyond the near-ground region become much gentle. In comparison to the measured values, it shows that the current numerical method can simulate the interaction between pavement and ambient atmosphere effectively and can be extended to urban microclimate simulation.

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Muddu, Shashank, Ashutosh Tamrakar, Preetanshu Pandey, and Rohit Ramachandran. "Model Development and Validation of Fluid Bed Wet Granulation with Dry Binder Addition Using a Population Balance Model Methodology." Processes 6, no. 9 (September 1, 2018): 154. http://dx.doi.org/10.3390/pr6090154.

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An experimental study in industry was previously carried out on a batch fluid bed granulation system by varying the inlet fluidizing air temperature, binder liquid spray atomization pressure, the binder liquid spray rate and the disintegrant composition in the formulation. A population balance model framework integrated with heat transfer and moisture balance due to liquid addition and evaporation was developed to simulate the fluid bed granulation system. The model predictions were compared with the industry data, namely, the particle size distributions (PSDs) and geometric mean diameters (GMDs) at various time-points in the granulation process. The model also predicted the trends for binder particle dissolution in the wetting liquid and the temperatures of the bed particles in the fluid bed granulator. Lastly, various process parameters were varied and extended beyond the region studied in the aforementioned experimental study to identify optimal regimes for granulation.

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42

Kjeldby, Tor Kindsbekken, and Ole Jørgen Nydal. "Experiments and Simulations of Local Upstream Gas Accumulation Giving Unstable Production in a Flowline/Riser System." SPE Journal 20, no. 03 (June 15, 2015): 598–609. http://dx.doi.org/10.2118/172997-pa.

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Summary A set of small-scale air/water experiments has been carried out in a flowline/riser system to demonstrate how local gas accumulation in regions upstream from a riser or a well may give unstable flow, with cycling liquid production at the riser outlet. This unstable flow phenomenon differs from the well-known severe-slugging instability phenomenon in that the instability is driven by gas expansion in the riser, and not by expansion in the upstream pipeline. A Lagrangian slug tracking model was extended with the option of solving problems with entrained gas in slugs, and used to simulate the experiments. A simplified pressure/momentum scheme is applied. Sensitivity analyses were carried out for selected parameters. Good correspondence between experiments and simulations was found with respect to the period of the instability cycle for this gravity-dominated system. The experimental stability limits are also well reproduced.

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Kim, D., and J. Kaluarachchi. "Predicting streamflows in snowmelt-driven watersheds using the flow duration curve method." Hydrology and Earth System Sciences 18, no. 5 (May 9, 2014): 1679–93. http://dx.doi.org/10.5194/hess-18-1679-2014.

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Abstract. Predicting streamflows in snow-fed watersheds in the Western United States is important for water allocation. Since many of these watersheds are heavily regulated through canal networks and reservoirs, predicting expected natural flows and therefore water availability under limited data is always a challenge. This study investigates the applicability of the flow duration curve (FDC) method for predicting natural flows in gauged and regulated snow-fed watersheds. Point snow observations, air temperature, precipitation, and snow water equivalent were used to simulate the snowmelt process with the SNOW-17 model, and extended to streamflow simulation using the FDC method with a modified current precipitation index. For regulated watersheds, a parametric regional FDC method was applied to reconstruct natural flow. For comparison, a simplified tank model was used considering both lumped and semi-distributed approaches. The proximity regionalization method was used to simulate streamflows in the regulated watersheds with the tank model. The results showed that the FDC method is capable of producing satisfactory natural flow estimates in gauged watersheds when high correlation exists between current precipitation index and streamflow. For regulated watersheds, the regional FDC method produced acceptable river diversion estimates, but it seemed to have more uncertainty due to less robustness of the FDC method. In spite of its simplicity, the FDC method is a practical approach with less computational burden for studies with minimal data availability.

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Yang, Tao, Mingjun Wei, Kun Jia, and James Chen. "A monolithic algorithm for the flow simulation of flexible flapping wings." International Journal of Micro Air Vehicles 11 (January 2019): 175682931984612. http://dx.doi.org/10.1177/1756829319846127.

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It has been a challenge to simulate flexible flapping wings or other three-dimensional problems involving strong fluid–structure interactions. Solving a unified fluid–solid system in a monolithic manner improves both numerical stability and efficiency. The current algorithm considered a three-dimensional extension of an earlier work which formulated two-dimensional fluid–structure interaction monolithically under a unified framework for both fluids and solids. As the approach is extended from a two-dimensional to a three-dimensional configuration, a cell division technique and the associated projection process become necessary and are illustrated here. Two benchmark cases, a floppy viscoelastic particle in shear flow and a flow passing a rigid sphere, are simulated for validation. Finally, the three-dimensional monolithic algorithm is applied to study a micro-air vehicle with flexible flapping wings in a forward flight at different angles of attack. The simulation shows the impact from the angle of attack on wing deformation, wake vortex structures, and the overall aerodynamic performance.

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Vadood, M., M. S. Johari, and A. R. Rahai. "A New Approach for Simulation of Hot Mix Asphalt; Numerical and Experimental." Journal of Mechanics 31, no. 6 (July 15, 2015): 701–11. http://dx.doi.org/10.1017/jmech.2015.36.

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ABSTRACTIn this study a novel approach for 3D modeling of cylindrical sample of hot mix asphalt (HMA) is presented. To this end, the cylindrical sample was divided into several slices and using a developed algorithm the processed images were extended to 3D volumetric objects to reconstruct the 3D microstructure of HMA. To evaluate the efficiency of the presented 3D model for prediction of mechanical behavior, HMA was regarded as a two-phase mixture; mastic phase and aggregate phase. The asphalt binder, filler, air voids and fine aggregates were considered as mastic with viscoelastic behavior and the aggregate was considered as an elastic material. Two models (Burger and generalized Kelvin) were studied for determining viscoelastic behavior of mastic. Finally, to verify the model using Finite Element Method (FEM) the behavior of the 3D model was simulated under different uniaxial compressive loads. A good agreement was observed between the simulated results and corresponding experimental data which indicates the efficiency of the proposed model to simulate three-dimensional asphalt.

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46

Helmus, Rhena, James Kratz, Kevin Potter, Pascal Hubert, and Roland Hinterhölzl. "An experimental technique to characterize interply void formation in unidirectional prepregs." Journal of Composite Materials 51, no. 5 (July 28, 2016): 579–91. http://dx.doi.org/10.1177/0021998316650273.

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Out-of-autoclave prepreg processing requires evacuation of volatiles in the early stages of processing to achieve an acceptable final void content. In this study, single prepreg plies were laid-up onto a glass tool to simulate a ply–ply interface, to gain an understanding of initial air entrapment and eventual removal mechanisms. The contact was recorded during processing with various edge breathing configurations to identify the relationship between evacuation pathways and contact evolution. The existence of preferential flow channels along the fibre direction of the material was demonstrated by characterizing the prepreg surface. Gas evacuation in those channels prevented contact during an extended ambient temperature vacuum hold. The contact between the prepreg and glass tool equilibrated around 80% during the ambient vacuum hold, and reached full contact at elevated temperature after a brief loss in contact due to moisture vaporization, when the resin pressure decreased to below the water vapour pressure.

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Hu, J., Z. Q. Lu, X. Y. Kan, and S. L. Sun. "Numerical Simulation on Interface Evolution and Impact of Flooding Flow." Shock and Vibration 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/794069.

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A numerical model based on Navier-Stokes equation is developed to simulate the interface evolution of flooding flows. The two-dimensional fluid domain is discretised by structured rectangular elements according to finite volume method (FVM). The interface between air and liquid is captured through compressive interface capturing scheme for arbitrary meshes (CICSAM) based on the idea of volume of fluid (VOF). semiimplicit method for pressure linked equations (SIMPLE) scheme is used for the pressure-velocity coupling. A second order upwind discretization scheme is applied for the momentum equations. Both laminar flow model and turbulent flow model have been studied and the results have been compared. Previous experiments and other numerical solutions are employed to verify the present results on a single flooding liquid body. Then the simulation is extended to two colliding flooding liquid bodies. The impacting force of the flooding flow on an obstacle has been also analyzed. The present results show a favourable agreement with those by previous simulations and experiments.

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48

Eckstein, Johannes, Roland Ruhnke, Stephan Pfahl, Emanuel Christner, Christopher Diekmann, Christoph Dyroff, Daniel Reinert, et al. "From climatological to small-scale applications: simulating water isotopologues with ICON-ART-Iso (version 2.3)." Geoscientific Model Development 11, no. 12 (December 14, 2018): 5113–33. http://dx.doi.org/10.5194/gmd-11-5113-2018.

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Abstract. We present the new isotope-enabled model ICON-ART-Iso. The physics package of the global ICOsahedral Nonhydrostatic (ICON) modeling framework has been extended to simulate passive moisture tracers and the stable isotopologues HDO and H218O. The extension builds on the infrastructure provided by ICON-ART, which allows for high flexibility with respect to the number of related water tracers that are simulated. The physics of isotopologue fractionation follow the model COSMOiso. We first present a detailed description of the physics of fractionation that have been implemented in the model. The model is then evaluated on a range of temporal scales by comparing with measurements of precipitation and vapor. A multi-annual simulation is compared to observations of the isotopologues in precipitation taken from the station network GNIP (Global Network for Isotopes in Precipitation). ICON-ART-Iso is able to simulate the main features of the seasonal cycles in δD and δ18O as observed at the GNIP stations. In a comparison with IASI satellite retrievals, the seasonal and daily cycles in the isotopologue content of vapor are examined for different regions in the free troposphere. On a small spatial and temporal scale, ICON-ART-Iso is used to simulate the period of two flights of the IAGOS-CARIBIC aircraft in September 2010, which sampled air in the tropopause region influenced by Hurricane Igor. The general features of this sample as well as those of all tropical data available from IAGOS-CARIBIC are captured by the model. The study demonstrates that ICON-ART-Iso is a flexible tool to analyze the water cycle of ICON. It is capable of simulating tagged water as well as the isotopologues HDO and H218O.

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Zwierzchowski, Ryszard, Marcin Malicki, and Maciej Lipka. "Innovative model of trigeneration system generating desalinated water, hot and cold by using low grade heat recovery from nuclear reactor set in cascade of sorption devices." E3S Web of Conferences 116 (2019): 00108. http://dx.doi.org/10.1051/e3sconf/201911600108.

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The paper introduces an innovative conceptual model of a trigeneration system based on implementation of sorption devices in cascade configuration: absorption heat pumps and adsorption chillers connected with thermal energy storage, for recovering useless heat from secondary cooling circuit of a research nuclear reactor. Proposed trigeneration source provides building with useful heat for the purposes of heating system with thermal energy storage and cold for air-conditioning purposes. Also, desalinated water covering technological demand is produced. Useful heat is produced by an absorption heat pump, cold and desalinated water by adsorption chiller/desalinator. For the described trigeneration system calculations based on commercially available equipment (lithium-bromate absorption heat pumps and silica-gel adsorption chillers with desalination option) and required heat/cold/desalinate demand have been carried out. Operational data collected from an existing installation extended by introducing thermal energy storage to the system was used to simulate the heat demand during the year. 5-year operational data from the “MARIA” research nuclear reactor located at the National Center for Nuclear Research in Świerk, Poland was used to simulate low source variations for the absorption heat pump operation. The results of model implementation demonstrate a series of promising effects on many levels of system operation, including production of desalinated water on a large scale and significant reduction of: (I) energy usage (by 40% when considering only heating scenario), (II) nuclear fuel consumption, (III) heat delivery losses.

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Akinshin, R. N., O. V. Esikov, D. A. Zatuchny, and A. V. Peteshov. "MODEL OF A MATRIX CROSSCORRELATION FUNCTION OF THE PROBING AND REFLECTED VECTOR SIGNALS FOR A CONCEPTUAL DESIGN OF A SYNTHETIC APERTURE RADAR ON AN AERIAL CARRIER." Civil Aviation High TECHNOLOGIES 22, no. 2 (April 24, 2019): 86–95. http://dx.doi.org/10.26467/2079-0619-2019-22-2-86-95.

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In order to simulate the process of design development in full on computer models, including virtual tests of the synthetic aperture radar on an air carrier in model media, the study develops a structural scheme of the conceptual design of the synthetic aperture radar on an air carrier. The scheme is invariant with respect to the type of an air carrier with a synthetic aperture radar: an aircraft, a helicopter, an unmanned aerial vehicle and similar ones: an air carrier "enters" it by only an automatic control system, a model of trajectory instabilities and a spectrum of frequencies of elastic oscillations of its design. To perform a computer simulation of radar systems with full polarization sensing, a model of a matrix cross-correlation function of probing and reflected vector signals is proposed. As a model of the scattering object, a set of independent point reflectors distributed over space and generally having different rates of motion is accepted. The reflected signal is a sum of elementary signals, their form completely repeats the shape of the emitted signal, and the amplitude, the phase and polarization are respectively determined by the coordinate, velocity and polarization parameters of elementary reflectors forming a spatially extended object. Taking into account the developed models for the formation of the vector sounding signal and the matrix response function of the distributed radar object, a block-diagram of the model of the matrix cross-correlation function of the emitted and reflected vector signals is proposed. A block-diagram is the basis for the development of an algorithm and a program for computer modeling of the primary signal processing in a radar station with full polarization sensing.

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Journal articles on the topic 'Simulate extended air showers'

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