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Journal articles on the topic 'LES numerical simulations'

Author: Grafiati

Published: 4 May 2024

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1

Kitiashvili, I. N., A. G. Kosovichev, A. A. Wray, and N. N. Mansour. "Numerical simulations of magnetic structures." Proceedings of the International Astronomical Union 6, S273 (August 2010): 315–19. http://dx.doi.org/10.1017/s1743921311015444.

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AbstractWe use 3D radiative MHD simulations of the upper turbulent convection layer for investigation of physical mechanisms of formation of magnetic structures on the Sun. The simulations include all essential physical processes, and are based of the LES (Large-Eddy Simulations) approach for describing the sub-grid scale turbulence. The simulation domain covers the top layer of the convection zone and the lower atmosphere. The results reveal a process of spontaneous formation of stable magnetic structures from an initially weak vertical magnetic field, uniformly distributed in the simulation domain. The process starts concentration of magnetic patches at the boundaries of granular cells, which are subsequently merged together into a stable large-scale structure by converging downdrafts below the surface. The resulting structure represents a compact concentration of strong magnetic field, reaching 6 kG in the interior. It has a cluster-like internal structurization, and is maintained by strong downdrafts extending into the deep layers.

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2

Zaussinger, F., and H. C. Spruit. "Semiconvection: numerical simulations." Astronomy & Astrophysics 554 (June 2013): A119. http://dx.doi.org/10.1051/0004-6361/201220573.

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CORCAU, Jenica-Ileana, and Liviu DINCA. "MATHEMATICAL MODEL AND NUMERICAL SIMULATIONS FOR PHOTOVOLTAIC PANELS." Review of the Air Force Academy 15, no. 3 (December 14, 2017): 47–56. http://dx.doi.org/10.19062/1842-9238.2017.15.3.5.

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4

Kik, Tomasz, Marek Slovacek, Jaromir Moravec, and Mojmir Vanek. "Numerical Simulations of Heat Treatment Processes." Applied Mechanics and Materials 809-810 (November 2015): 799–804. http://dx.doi.org/10.4028/www.scientific.net/amm.809-810.799.

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Welding and heat treatment are a modern, high efficient production technologies. During last few years requirements for quality of the welded joints have been constantly increasing in all production areas. Unfortunately, this approach increases the cost of production due to demand of intense experimental or prototype work prior the use of technology to make a final product. Preliminary experiments have to take into account proper chose of welding technology, materials, welding parameters, clamping and final optimization the welding conditions. All of these activities can be supported or even replaced by numerical simulations based on finite elements method. Tremendous advance in field of numerical simulation, facilitates very high correlation of simulation and experimental results bringing this new approach to common use. This paper highlight to usefulness of numerical simulation in heat treatment of bulk materials in various production stages. It was shown that it is possible to predict formation of metallurgical phases, hardness distribution, strains and stresses during and after quenching process. Simulations of different heating conditions and cooling media makes it possible to simulate processes such as heating, quenching, carburizing and nitriding.

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5

Demeio, Lucio, and James Paul Holloway. "Numerical simulations of BGK modes." Journal of Plasma Physics 46, no. 1 (August 1991): 63–84. http://dx.doi.org/10.1017/s0022377800015956.

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Solutions of the full nonlinear Vlasov–Poisson system for a one-dimensional unmagnetized plasma that correspond to undamped travelling waves near Maxwellian equilibria are analysed numerically using the splitting scheme algorithm. The numerical results are clearly in favour of the existence of such waves and confirm that there is a critical phase velocity below which they cannot be constructed.

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6

Komissarov, Serguei, and Oliver Porth. "Numerical simulations of jets." New Astronomy Reviews 92 (June 2021): 101610. http://dx.doi.org/10.1016/j.newar.2021.101610.

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7

Ramunigari, Naveen KumarG, and Debarshi Roy. "Numerical simulations of thrombosis." Chronicles of Young Scientists 4, no. 2 (2013): 130. http://dx.doi.org/10.4103/2229-5186.115552.

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Yasui, Kyuichi. "Numerical simulations for sonochemistry." Ultrasonics Sonochemistry 78 (October 2021): 105728. http://dx.doi.org/10.1016/j.ultsonch.2021.105728.

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9

Guillaume, F. "Numerical simulations and spectroscopy." École thématique de la Société Française de la Neutronique 12 (2011): 3–14. http://dx.doi.org/10.1051/sfn/201112002.

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Petit, S. "Numerical simulations and magnetism." École thématique de la Société Française de la Neutronique 12 (2011): 105–21. http://dx.doi.org/10.1051/sfn/201112006.

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11

Bascoul, Guillaume P. "Numerical simulations of semiconvection." Proceedings of the International Astronomical Union 2, S239 (August 2006): 317–19. http://dx.doi.org/10.1017/s1743921307000658.

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AbstractUsing a semiconvective model based on thermohaline convection, we investigate the case of an expanding core of a main-sequence massive star. The numerical simulations at high Prandtl number show a flow consistent with the assumption that a dynamically neutral layer sits between the core and the radiative envelope. More simulations at low Prandtl number are needed to infer scaling laws applicable to astrophysical regimes.

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Botha, G. J. J., A. M. Rucklidge, and N. E. Hurlburt. "Numerical simulations of sunspots." Proceedings of the International Astronomical Union 2, S239 (August 2006): 507–9. http://dx.doi.org/10.1017/s1743921307001019.

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AbstractThe origin, structure and evolution of sunspots are investigated using a numerical model. The compressible MHD equations are solved with physical parameter values that approximate the top layer of the solar convection zone. A three dimensional (3D) numerical code is used to solve the set of equations in cylindrical geometry, with the numerical domain in the form of a wedge. The linear evolution of the 3D solution is studied by perturbing an axisymmetric solution in the azimuthal direction. Steady and oscillating linear modes are obtained.

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13

Durisen, R. H., S. Yang, and R. Grabhorn. "Numerical Simulations of Fission." Highlights of Astronomy 8 (1989): 133–35. http://dx.doi.org/10.1017/s1539299600007619.

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14

Antonioletti, M., and A. H. Nelson. "Numerical Simulations of M51." Symposium - International Astronomical Union 186 (1999): 105–8. http://dx.doi.org/10.1017/s0074180900112331.

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No conference on the interaction of galaxies would be complete without a contribution on M51 (NGC5194) and its companion NGC5195. Much observational and theoretical work has been carried out to try to understand this interacting pair, and to elucidate the morphological features and weak AGN which are thought to be the result of the interaction.

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15

Hawley, John F. "Numerical simulations of AGNs." Advances in Space Research 8, no. 2-3 (January 1988): 119–26. http://dx.doi.org/10.1016/0273-1177(88)90394-8.

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16

Dommermuth, Douglas G., and Rebecca C. Y. Mui. "Numerical Simulation of Free-Surface Turbulence." Applied Mechanics Reviews 47, no. 6S (June 1, 1994): S163—S165. http://dx.doi.org/10.1115/1.3124397.

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Direct numerical simulations and large-eddy simulations of turbulent free-surface flows are currently being performed to investigate the roughening of the surface, and the scattering, radiation, and dissipation of waves by turbulence. The numerical simulation of turbulent free-surface flows is briefly reviewed. The numerical, modeling, and hardware issues are discussed.

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Laín-Beatove, Santiago, Manuel J. García.Ruiz, Brian Quintero-Arboleda, and Santiago Orrego-Bustamante. "CFD Numerical simulations of Francis turbines." Revista Facultad de Ingeniería Universidad de Antioquia, no. 51 (March 20, 2013): 31–40. http://dx.doi.org/10.17533/udea.redin.14917.

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In this paper the description of the internal flow in a Francis turbine is addressed from a numerical point of view. The simulation methodology depends on the objectives. On the one hand, steady simulations are able to provide the hill chart of the turbine and energetic losses in its components. On the other hand, unsteady simulations are required to investigate the fluctuating pressure dynamics and the rotor-stator interaction. Both strategies are applied in this paper to a working Francis turbine in Colombia. The employed CFD package is ANSYS-CFX v. 11. The obtained results are in good agreement with the in site experiments, especially for the characteristic curve.

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Piché, R., and A. Ellman. "Numerical Integration of Fluid Power Circuit Models Using Two-Stage Semi-Implicit Runge-Kutta Methods." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 208, no. 3 (May 1994): 167–75. http://dx.doi.org/10.1243/pime_proc_1994_208_114_02.

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Fluid power circuits that contain fluid volumes of different orders of magnitude are difficult to simulate because the system of ordinary differential equations is numerically stiff. Even algorithms specially designed for stiff systems require excessively small time steps to avoid numerical oscillation in simulations of some circuits. In this paper the accuracy and numerical stability of several two-stage semi-implicit Runge-Kutta methods that have been proposed in circuit simulation literature are analysed and compared. It is shown that, for integration of very stiff circuits, the best method in this class is an L-stable method. A simple numerical example is used to verify the theoretical results. The example includes a novel way of modelling orifice flow that is especially suitable for numerical simulations.

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19

Kozelkov, Andrey, Andrey Kurkin, Vadim Kurulin, Kseniya Plygunova, and Olga Krutyakova. "Validation of the LOGOS Software Package Methods for the Numerical Simulation of Cavitational Flows." Fluids 8, no. 3 (March 22, 2023): 104. http://dx.doi.org/10.3390/fluids8030104.

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Verification problems and numeric simulation of cavitation processes with the help of LOGOS computational fluid dynamics software are presented in this article. The Volume of Fluid method realized within LOGOS allowing numerical simulation of double-phase problems with a free surface is used for numeric simulation. Cavitation is resolved by updating the method with the account for interphase mass exchange; its condensation and evaporation parameters are calculated with the use of the Schnerr–Sauer and Zwart–Gerber–Belamri cavitation models. Numerical simulation results of most actual test problems considering turbulence and having reliable numerical data are presented, including simulations of flow around cylinders with flat and hemispherical end surfaces for various cavitation numbers. Numerical simulation results are presented for the process of rotation of a VP1304 screw propeller in the cavitational mode. Numerical experiments prove the operability of the implemented method.

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20

Kumar, Saurabh, Ho Jun Kim, and Ali Beskok. "Numerical Simulations of Peristaltic Mixing." Journal of Fluids Engineering 129, no. 11 (June 6, 2007): 1361–71. http://dx.doi.org/10.1115/1.2786480.

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Numerical simulations of two-dimensional flow and species transport in a peristaltically driven closed mixer are performed as a function of the Reynolds number (Re⩽6288) and the normalized traveling wave amplitude (ε⩽0.3) at low to moderate Schmidt number (Sc⩽10) conditions. The mixer consists of a rectangular box with a traveling wave motion induced on its bottom surface. Flow and species mixing are produced by the surface motion. The numerical algorithm, based on an arbitrary Lagrangian–Eulerian spectral element formulation, is verified using the asymptotic solutions for small wave amplitude cases. Kinematics of large-deformation conditions are studied as a function of the Reynolds number. Species mixing is simulated at various Re and Sc conditions. Mixing index inverse (M−1) is utilized to characterize the mixing efficiency, where M−1∝exp(Pe−αt) is observed as the long-time behavior. Simulation data are utilized to determine the exponent α at various Re and Sc conditions. For all simulations, 0.28⩽α⩽0.35, typical of partially chaotic flows, have been observed. The effect of flow kinematics and species diffusion on mixing is interpreted.

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21

INAMORI, Kohjiroh, Kaoru HAYAMA, Mitsuko TAKADA, Masahiro OHSHIMA, and Masataka TANIGAKI. "Numerical Simulation for Polymeric Foaming. (1). Numerical Simulations and Experiments on Homogeneous Nucleation." Seikei-Kakou 11, no. 3 (1999): 194–201. http://dx.doi.org/10.4325/seikeikakou.11.194.

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22

GAWRON, P., and J. A. MISZCZAK. "NUMERICAL SIMULATIONS OF MIXED STATE QUANTUM COMPUTATION." International Journal of Quantum Information 03, no. 01 (March 2005): 195–99. http://dx.doi.org/10.1142/s0219749905000748.

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We describe the [Formula: see text] package of functions useful for simulations of quantum algorithms and protocols. The presented package allows one to perform simulations with mixed states. We present numerical implementation of important quantum mechanical operations — partial trace and partial transpose. Those operations are used as building blocks of algorithms for analysis of entanglement and quantum error correction codes. A simulation of Shor's algorithm is presented as an example of package capabilities.

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23

Kanak, Katharine M., Jerry M. Straka, and David M. Schultz. "Numerical Simulation of Mammatus." Journal of the Atmospheric Sciences 65, no. 5 (May 1, 2008): 1606–21. http://dx.doi.org/10.1175/2007jas2469.1.

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Abstract Mammatus are hanging lobes on the underside of clouds. Although many different mechanisms have been proposed for their formation, none have been rigorously tested. In this study, three-dimensional numerical simulations of mammatus on a portion of a cumulonimbus cirruslike anvil are performed to explore some of the dynamic and microphysical factors that affect mammatus formation and evolution. Initial conditions for the simulations are derived from observed thermodynamic soundings. Five observed soundings are chosen—four were associated with visually observed mammatus and one was not. Initial microphysical conditions in the simulations are consistent with in situ observations of cumulonimbus anvil and mammatus. Mammatus form in the four model simulations initialized with the soundings for which mammatus were observed, whereas mammatus do not form in the model simulation initialized with the no-mammatus sounding. Characteristics of the modeled mammatus compare favorably to previously published mammatus observations. Three hypothesized formation mechanisms for mammatus are tested: cloud-base detrainment instability, fallout of hydrometeors from cloud base, and sublimation of ice hydrometeors below cloud base. For the parameters considered, cloud-base detrainment instability is a necessary, but not sufficient, condition for mammatus formation. Mammatus can form without fallout, but not without sublimation. All the observed soundings for which mammatus were observed feature a dry-adiabatic subcloud layer of varying depth with low relative humidity, which supports the importance of sublimation to mammatus formation.

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24

Katayama, Masahide. "Simulation. Numerical Simulations of Shocks in Fluids and Solids." REVIEW OF HIGH PRESSURE SCIENCE AND TECHNOLOGY 8, no. 4 (1998): 251–59. http://dx.doi.org/10.4131/jshpreview.8.251.

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25

Kächele, Thomas, Rudolf P. M. Rademakers, Tim Schneider, and Reinhard Niehuis. "Numerical simulations of an intake-compressor system." Journal of the Global Power and Propulsion Society 2 (October 3, 2018): VQB6CK. http://dx.doi.org/10.22261/jgpps.vqb6ck.

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Integrated propulsion plays a major role in future civil and military aircraft design. A key component of these systems are highly bent intake geometries. As the flow passes through such ducts, combined total pressure and swirl distortions are generated which have a negative impact on compressor performance, safety margin, and durability. Due to weight and space limitations, a close coupling of intake and compressor is necessary. An experimental test case including a highly bent intake geometry and a state of the art turbofan engine was established and extensive measurement data was acquired. This publication compares results of three different numerical approaches to this test data: Isolated intake simulations, isolated compressor simulations with distorted inflow conditions, and a coupled simulation of intake and three stage compressor. The isolated intake simulation is able to reproduce the static wall pressure field of the intake as well as the occurring flow separation. Towards the interface plane to the compressor however, significant deviations are observed. The upstream effect of the compressor working under the combined pressure swirl distortion is assessed via the second simulation approach. The influence of the swirl and total pressure distortion on the compressor is first simulated separately and then compared to the impact of the combined distortion. The coupled intake-compressor simulation reveals the manipulation of the intake flow field by an upstream static pressure field. In contrast to experiments a slightly unsteady operation point and an asymmetric intake flow field were observed.

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Iordache, Dan-Alexandru, Paul Sterian, Andreea Rodica Sterian, and Florin Pop. "Complex Computer Simulations, Numerical Artifacts, and Numerical Phenomena." International Journal of Computers Communications & Control 5, no. 5 (December 1, 2010): 744. http://dx.doi.org/10.15837/ijccc.2010.5.2234.

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The study of some typical complex computer simulations, presenting one or more Complexity features, as the: a) symmetry breaking, b) nonlinear properties, c) dissipative processes, d) high-logical depth, e) selforganizing processes, etc allows to point out some several numerical artifacts, namely the: (i) distortions, (ii) scattering, (iii) pseudo-convergence, (iv) instability, (v) mis-leading (false) symmetry-breaking simulations and others. The detailed analysis of these artifacts allowed clarifying the numerical mechanisms of some such artifacts, which can be named in following numerical phenomena, because their basic features can be exactly predicted.

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Granda-Muñoz, Guido, Enrique Vázquez-Semadeni, Gilberto C. Gómez, and Manuel Zamora-Avilés. "A resolution criterion based on characteristic time-scales for MHD simulations of molecular clouds." Monthly Notices of the Royal Astronomical Society 510, no. 4 (December 16, 2021): 5062–68. http://dx.doi.org/10.1093/mnras/stab3663.

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ABSTRACT We investigate the effect of numerical magnetic diffusion in magnetohydrodynamic (MHD) simulations of magnetically supported molecular clouds. To this end, we have performed numerical studies on adaptive mesh isothermal simulations of marginally subcritical molecular clouds. We find that simulations with low and intermediate resolutions collapse, contrary to what is theoretically expected. However, the simulation with the highest numerical resolution oscillates around an equilibrium state without collapsing. In order to quantify the numerical diffusion of the magnetic field, we ran a second suit of current-sheet simulations in which the numerical magnetic diffusion coefficient can be directly measured and computed the corresponding diffusion times at various numerical resolutions. On this basis, we propose a criterion for the resolution of magnetic fields in MHD simulations based on requiring that the diffusion time to be larger than the characteristic time-scale of the physical process responsible for the dynamic evolution of the structure.

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Makhmanazarov, Ramdas, Ilya Tseplyaev, Sergey Shipilov, and Natalya Krivova. "Estimation of SAR Average in Rats during 5G NR Chronic Exposure." Applied Sciences 14, no. 1 (December 26, 2023): 208. http://dx.doi.org/10.3390/app14010208.

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To study physiological reactions in the brain and skin of higher mammals exposed to chronic radiofrequency radiation, specific absorption ratio (SAR) determination is required and time-consuming numerical methods are used. The paper deals with the estimation of the whole-body specific absorption rate (SAR) in rats chronically exposed to external electromagnetic fields, as well as the development of a laboratory setup simulating the operation of a fifth-generation 5G New Radio base station (with a signal bandwidth of 15 MHz and a carrier frequency of 2.4 GHz). The paper presents a modified method for theoretical SAR estimation for one-sided irradiation and distributed absorption. Mean whole-body SAR values were estimated by the proposed method and numerically modeled with the CST Microwave Studio simulation software 2020package using primitive rat models. Dielectric parameters in the numerical simulation were used from the software library. The IEEE/IEC 62704-1 algorithm was used to investigate SAR in numerical simulations. The theoretical estimates and numerical simulations were compared for different SAR distributions and were found to be qualitatively comparable. The differences between approximate theoretical estimates and numerical simulations are 7% and 10% for distributed and non-distributed absorptions, respectively. The proposed method, which takes into account the decreasing power flux density, can be used to estimate the approximate whole-body SAR during chronic electromagnetic field exposure in rats.

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29

Liu, Lijun, Agung Premono, Reza Miresmaeili, and Hiroshi Kanayama. "F104 Numerical Simulations of Hydrogen-Plasticity Interactions in Metallic Materials." Proceedings of The Computational Mechanics Conference 2011.24 (2011): _F—9_—_F—12_. http://dx.doi.org/10.1299/jsmecmd.2011.24._f-9_.

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Callaghan, Fraser M., and Tim David. "Numerical Simulations of an Idealised Artificial Heart Valve(Cardiovascular Mechanics)." Proceedings of the Asian Pacific Conference on Biomechanics : emerging science and technology in biomechanics 2004.1 (2004): 63–64. http://dx.doi.org/10.1299/jsmeapbio.2004.1.63.

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31

Yokoyama, T., and K. Shibata. "Numerical Simulations of Solar Flares." Symposium - International Astronomical Union 195 (2000): 445–46. http://dx.doi.org/10.1017/s0074180900163466.

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We study reconnection and chromospheric evaporation in flares using a numerical code including nonlinear, anisotropic heat conduction (Yokoyama & Shibata 1998). The two-dimensional, nonlinear, time-dependent, resistive, compressible MHD equations are solved. The evolution from the rise phase to (the early part of) the decay phase of a solar flare is qualitatively reproduced in this simulation. Based on the results, we obtained a relationship between the flare temperature and the coronal magnetic field strength. We assume that the energy input to a loop balances with the conductive cooling rate, that the temperature at the loop apex is TA ≍ (2QL2/κ0)2/7, where Q is the volumetric heating rate, that L is the half-length of the loop, and that the Spitzer thermal conductivity constant is κ0 = 10−6 CGS. In our simulations, the heating mechanism is magnetic reconnection, so the heating rate is described as Q = B2/(4π) · Vin/L · l/sin Θ, where B is the coronal magnetic field strength, Vin is the inflow velocity (≍ 0.1 VA from our result and also from Petschek's theory), and Θ is the angle between the slow-mode MHD shock and the loop and is approximately given by sin Θ ≍ Vin/VA. By manipulating the equations, we find where ρ is the mass density of the corona. The simulation results show very good agreement with this scaling law.

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32

Skinner, J. W., and J. Y.-K. Cho. "Numerical convergence of hot-Jupiter atmospheric flow solutions." Monthly Notices of the Royal Astronomical Society 504, no. 4 (April 16, 2021): 5172–87. http://dx.doi.org/10.1093/mnras/stab971.

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ABSTRACT We perform an extensive study of numerical convergence for hot-Jupiter atmospheric flow solutions in simulations employing a setup commonly used in extrasolar planet studies – a resting state thermally forced to a prescribed temperature distribution on a short time-scale at high altitudes. Convergence is assessed rigorously with (i) a highly accurate pseudospectral model that has been explicitly verified to perform well under hot-Jupiter flow conditions and (ii) comparisons of the kinetic energy spectra, instantaneous (unaveraged) vorticity fields and temporal evolutions of the vorticity field from simulations that are numerically equatable. In the simulations, the (horizontal as well as vertical) resolution, dissipation operator order, and viscosity coefficient are varied with identical physical and initial setups. All of the simulations are compared against a fiducial reference simulation at high horizontal resolution and dissipation order (T682 and ∇ 16, respectively) – as well as against each other. Broadly, the reference solution features a dynamic, zonally (east–west) asymmetric jet with a copious amount of small-scale vortices and gravity waves. Here, we show that simulations converge to the reference simulation only at T341 resolution and with ∇ 16 dissipation order. Below this resolution and order, simulations either do not converge or converge to unphysical solutions. The general convergence behaviour is independent of the vertical range of the atmosphere modelled, from $\sim 2 \times 10^{-3}$MPa to $\sim 2 \times 10^1$ MPa. Ramifications for current extrasolar planet atmosphere modelling and observations are discussed.

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Sakash, Aaron, Sumit Moondra, and Brad L. Kinsey. "Effect of Yield Criterion on Numerical Simulation Results Using a Stress-Based Failure Criterion." Journal of Engineering Materials and Technology 128, no. 3 (March 19, 2006): 436–44. http://dx.doi.org/10.1115/1.2204951.

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Determining tearing concerns in numerical simulations of sheet metal components is difficult since the traditional failure criterion, which is strain-based, exhibits a strain path dependence. A stress-based, as opposed to a strain-based, failure criterion has been proposed and demonstrated analytically, experimentally in tube forming, and through numerical simulations. The next step in this progression to the acceptance of a stress-based forming limit diagram is to demonstrate how this failure criterion can be used to predict failure of sheet metal parts in numerical simulations. In this paper, numerical simulation results for dome height specimens are presented and compared to experimental data. This procedure was repeated for various yield criteria to examine the effect of this parameter on the ability to predict failure in the numerical simulations. Reasonable agreement was obtained comparing the failure predicted from numerical simulations and those found experimentally, in particular for the yield criterion which has been shown to best characterize the material used in this study.

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Bretti, Gabriella. "Differential Models, Numerical Simulations and Applications." Axioms 10, no. 4 (October 19, 2021): 260. http://dx.doi.org/10.3390/axioms10040260.

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Differential models, numerical methods and computer simulations play a fundamental role in applied sciences. Since most of the differential models inspired by real world applications have no analytical solutions, the development of numerical methods and efficient simulation algorithms play a key role in the computation of the solutions to many relevant problems. Moreover, since the model parameters in mathematical models have interesting scientific interpretations and their values are often unknown, estimation techniques need to be developed for parameter identification against the measured data of observed phenomena. In this respect, this Special Issue collects some important developments in different areas of application.

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Grecu, I. S., G. Dunca, D. M. Bucur, and M. J. Cervantes. "URANS numerical simulations of pulsating flows considering streamwise pressure gradient on asymmetric diffuser." IOP Conference Series: Earth and Environmental Science 1079, no. 1 (September 1, 2022): 012087. http://dx.doi.org/10.1088/1755-1315/1079/1/012087.

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Abstract The paper focuses on implementing the wall model developed by Manhart, in Reynolds Averaged Navier - Stokes (RANS) turbulence models used in the field of Computational Fluid Dynamics (CFD). This wall model considers the influence of the streamwise pressure gradient in addition to the existing wall models used in the usual CFD codes. In the present work, two RANS numerical simulations are carried out using the k-ω Shear Stress Transport (SST) turbulence model on an asymmetric diffuser geometry. One numerical simulation is carried out using the implementation of the Manhart wall model in the k-ω SST turbulence model, and the other numerical simulation is performed using the standard formulation of the k-ω SST turbulence model. The numerical simulations carried out using the Manhart wall model and the standard formulation of the k-ω SST are compared with experimental measurements made on the asymmetric diffuser experimental installation. The numerical simulations are carried out using a free, open-source CFD tool, Code_Saturne. The comparisons between numerical simulations and the experimental data are in good agreement in the boundary layer of the flow inside the diffuser. The Manhart wall model had a faster convergence resulting in a shorter simulation time.

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Mitruţ, R., D. M. Bucur, G. Dunca, and M. J. Cervantes. "Global linear stability analysis of the flow inside a conical draft tube." IOP Conference Series: Earth and Environmental Science 1079, no. 1 (September 1, 2022): 012049. http://dx.doi.org/10.1088/1755-1315/1079/1/012049.

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Abstract The paper presents the numerical simulations of the flow inside the draft tube of Francis-99 turbine at the part load (PL) operating condition. The rotating vortex rope (RVR) is a phenomenon that occurs during the PL operating regime inside the draft tube of hydraulic turbines. To reduce the computational cost, the numerical simulations are carried out in two steps. Firstly, steady state numerical simulations are performed in a reduced geometry of the runner which is made of a runner passage and part of the draft tube. The velocity profiles from the steady state simulation are used as a boundary condition for unsteady numerical simulation on the inlet of the full draft tube geometry. The velocities from the numerical simulations are time-averaged over a period of 5 RVR rotations and validated with the experimental velocities averaged over the same period. Further, a two-dimensional (2D) linear global stability analysis is performed on a plane extracted from the cone of the draft tube using the time-averaged flow. The frequency of three-dimensional (3D) flow simulation and of the 2D stability analysis are found to be in good agreement with the experimental frequency.

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Sherek, Paul A., Louis G. Hector, John R. Bradley, Paul E. Krajewski, and Eric M. Taleff. "Simulation and Experiments for Hot Forming of Rectangular Pans in Fine-Grained Aluminum Alloy AA5083." Key Engineering Materials 433 (March 2010): 185–95. http://dx.doi.org/10.4028/www.scientific.net/kem.433.185.

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Accurate numerical simulation capability is critical to the development and implementation of hot forming technologies. Numerical simulations were developed for gas-pressure forming of commercial, fine-grained aluminum-magnesium (AA5083) material into deep pan shapes at 450°C. These simulations utilize a material constitutive model recently developed for fine-grained AA5083 materials as a user-defined routine in commercial Finite Element Method (FEM) software. Results from simulations are compared against data from gas-pressure forming experiments, which used the same forming conditions and die geometries. Specifically, local sheet thinning and radius of curvature in edges and corners are compared between simulation and experiment. Numerical simulations are in good agreement with experiments for local sheet thinning of up to 50%. For locations where sheet thinning exceeds 50%, simulations predict less thinning and larger formed radii than observed in experiments. It is likely that cavitation, which is not accounted for in simulations, plays a significant role in causing a decrease in simulation prediction accuracy for thinning values greater than 50%. This study demonstrates a simulation capability that is potentially of significant practical use for predicting the hot gas-pressure forming of fine-grained AA5083 material.

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SUGAR, R. L. "NUMERICAL STUDIES OF MANY ELECTRON SYSTEMS." International Journal of Modern Physics C 01, no. 02n03 (September 1990): 215–32. http://dx.doi.org/10.1142/s0129183190000128.

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The numerical simulation of many electron systems in condensed matter physics is described. Numerical algorithms are discussed in detail, and results are presented from simulations of the Hubbard model in two and three dimensions.

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Karaman, Alara, Barbaros C¸etin, and Mehmet Bülent Özer. "Numerical simulation and experimental studies on acoustofluidic separation of microparticles using 3D printed chips." Journal of the Acoustical Society of America 153, no. 3_supplement (March 1, 2023): A34. http://dx.doi.org/10.1121/10.0018057.

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Principles of acoustofluidics can be used to manipulate and separate microparticles and cells in microchannels. In this study using numerical simulations, we will be investigating the limits of fundamental assumptions used in acoustofluidic such as a limited acoustic scattered field or fluid flow interaction between the particles/cells. A device-level numerical simulation tool will be used which accounts for the effect of the piezoelectric materials, interactions between the microparticles/cells fluid flow-field and the acoustic-field in the microchannel. Also, in this study, different numerical acoustic and mechanical models of biological cells will be investigated and the conditions (frequency, channel dimensions, etc.), which favor the acoustofluidic separation of cells with similar mechanical properties will be studied numerically. Finally, the results of the numerical simulations will be utilized, and experimental studies will be demonstrated, which separate microparticles/cells in a 3D printed polymeric chip.

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TSUCHIYA, Takao. "Numerical simulations of sound propagation." Choonpa Igaku 45, no. 1 (2018): 15–23. http://dx.doi.org/10.3179/jjmu.jjmu.r.94.

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NOZAKI, Osamu. "Flow visualization in numerical simulations." JOURNAL OF THE FLOW VISUALIZATION SOCIETY OF JAPAN 8, no. 28 (1988): 39–44. http://dx.doi.org/10.3154/jvs1981.8.39.

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Shibue, Tadashi, Kazuyuki Kato, Yasushi Kumakura, and Yutaka Toi. "Numerical Simulations on Ice Failure." Journal of the Society of Naval Architects of Japan 1987, no. 161 (1987): 373–81. http://dx.doi.org/10.2534/jjasnaoe1968.1987.373.

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Lipatnikov, Andrei N. "Numerical Simulations of Turbulent Combustion." Fluids 5, no. 1 (February 10, 2020): 22. http://dx.doi.org/10.3390/fluids5010022.

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Manish Kumar, N., Sk Sameer, and K. Divya. "Numerical Simulations of Composite Materials." IOP Conference Series: Earth and Environmental Science 982, no. 1 (March 1, 2022): 012019. http://dx.doi.org/10.1088/1755-1315/982/1/012019.

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Abstract Throughout the last decade, the usage of fiber reinforced polymer (FRP) reinforcements in civil infrastructure has risen exponentially, owing to its superior corrosion protection, high durability, and non-magnetization characteristics. Furthermore, as a result of the poor modulus of elasticity of the FRP composites and its non-yielding properties, significant deflection and broad fractures are seen in the FRP reinforced concrete components under consideration. The emphasis of present study is on the behavior of FRP-reinforced concrete beams. The total of nine finite element-based simulations were carried out (ABAQUS). The concrete damage plasticity modelling was considered while performing the analysis. Three different kinds of FRP bars such as CFRP, BFRP, and GFRP, were utilized as reinforcement in longitudinal and transverse direction for concrete beams. Literature was used to validate the numerical findings, and the parametric research has been carried out for varying factors, such as the diameter size, number of bars, the kind of FRP bars used, and the longitudinal arrangement of FRP bars. When CFRP bars were utilized, the load capacity increased by anywhere from 8.88% to 62.92%. Beams that have been reinforced with CFRP carry more weight than beams reinforced with GFRP and BFRP. The increase in CFRP bars tends to give some ductility to the beam via the bi-linear load-to-ductility curve. In similarly, the GFRP reinforced beams improve the ductility of the structure as a whole.

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Cleveland, Judah L., Jeffrey A. Smith, and James P. Collins. "Factor Effects in Numerical Simulations." Journal of the Atmospheric Sciences 77, no. 7 (July 1, 2020): 2439–51. http://dx.doi.org/10.1175/jas-d-19-0263.1.

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AbstractNumerical simulations allow users to adjust factor settings in experimental runs to understand how changes in those factors affect the output. However, it is not straightforward to analyze these outputs when multiple input factors are changed, especially simultaneously. For the atmospheric sciences, Stein and Alpert introduced a method they termed “factor separation” in order to separate the “pure contribution” of a factor from “pure interactions” of combinations of factors. Although factor separation appears to be used exclusively within the atmospheric sciences, other communities achieve a similar result by computing “main effects” via design of experiments methods. While both methods yield different estimates for the factor effects or contributions, we show that factor separation effects are identical to “simple effects” in the design of experiments literature. We demonstrate how both factor separation effects and design of experiments main effects correspond to multiple linear regression coefficients with different coding methods; thus, effect estimates produced by each method are equivalent through a variable transformation. We illustrate the application of both methods using a shallow-water simulation. This connection between factor separation and the design of experiments discipline extends factor separation to more applications by making available design of experiments methods for decreasing the computational cost and calculating effects for factors with more than two settings, both of which are limitations of factor separation.

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Cooper, G. R., D. A. Tidman, and M. L. Bundy. "Numerical Simulations of the Slingatron." Journal of Propulsion and Power 18, no. 2 (March 2002): 338–43. http://dx.doi.org/10.2514/2.5939.

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Peiran, Sebastien. "NUMERICAL SIMULATIONS OF GALAXY FORMATION." Publications of The Korean Astronomical Society 25, no. 3 (September 30, 2010): 71–76. http://dx.doi.org/10.5303/pkas.2010.25.3.071.

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PUWAL, STEFFAN, and BRADLEY J. ROTH. "NUMERICAL SIMULATIONS OF SYNCHRONIZED PACING." Journal of Biological Systems 14, no. 01 (March 2006): 101–12. http://dx.doi.org/10.1142/s0218339006001684.

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Pak et al.1 demonstrated an experimental technique for termination of fibrillation in the heart. Their method used feedback pacing, and resulted in an eight-fold increase in the success rate compared to conventional overdrive pacing. Our goal is to study this technique numerically. Computer simulations were performed using the Fenton-Karma model of membrane excitability, with a correction introduced to allow more realistic modeling of external stimulation. We found that both overdrive pacing and independent synchronized pacing resulted in significantly improved success compared to spontaneous termination of fibrillation. We conclude that synchronized pacing may provide a low-energy alternative to traditional defibrillation.

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Bilbao, L., and L. Bernal. "Dense magnetized plasma numerical simulations." Plasma Sources Science and Technology 19, no. 3 (May 21, 2010): 034024. http://dx.doi.org/10.1088/0963-0252/19/3/034024.

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Ceperley, David. "Numerical Simulations in Superfluid Helium." Physica Scripta T33 (January 1, 1990): 11. http://dx.doi.org/10.1088/0031-8949/1990/t33/002.

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