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In magnetically confined plasmas used in Tokamak, turbulence is respon-sible for specific transport that limits the performance of this kind of reactors. Gyroki-netic simulations are able to capture ion and electron turbulence that give rise to heat losses, but require also state-of-the-art HPC techniques to handle computation costs. Such simulations are a major tool to establish good operating regime in Tokamak such as ITER, which is currently being built. Some of the key issues to address more re- alistic gyrokinetic simulations are: efficient and robust numerical schemes, accurate geometric description, good parallelization algorithms. The framework of this work is the Semi-Lagrangian setting for solving the gyrokinetic Vlasov equation and the Gy-sela code. In this paper, a new variant for the interpolation method is proposed that can handle the mesh singularity in the poloidal plane at r = 0 (polar system is used for the moment in Gysela). A non-uniform meshing of the poloidal plane is proposed instead of uniform one in order to save memory and computations. The interpolation method, the gyroaverage operator, and the Poisson solver are revised in order to cope with non-uniform meshes. A mapping that establish a bijection from polar coordinates to more realistic plasma shape is used to improve realism. Convergence studies are provided to establish the validity and robustness of our new approach.
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Veltri, P., G. Nigro, F. Malara, V. Carbone, and A. Mangeney. "Intermittency in MHD turbulence and coronal nanoflares modelling." Nonlinear Processes in Geophysics 12, no. 2 (February 9, 2005): 245–55. http://dx.doi.org/10.5194/npg-12-245-2005.
Abstract. High resolution numerical simulations, solar wind data analysis, and measurements at the edges of laboratory plasma devices have allowed for a huge progress in our understanding of MHD turbulence. The high resolution of solar wind measurements has allowed to characterize the intermittency observed at small scales. We are now able to set up a consistent and convincing view of the main properties of MHD turbulence, which in turn constitutes an extremely efficient tool in understanding the behaviour of turbulent plasmas, like those in solar corona, where in situ observations are not available. Using this knowledge a model to describe injection, due to foot-point motions, storage and dissipation of MHD turbulence in coronal loops, is built where we assume strong longitudinal magnetic field, low beta and high aspect ratio, which allows us to use the set of reduced MHD equations (RMHD). The model is based on a shell technique in the wave vector space orthogonal to the strong magnetic field, while the dependence on the longitudinal coordinate is preserved. Numerical simulations show that injected energy is efficiently stored in the loop where a significant level of magnetic and velocity fluctuations is obtained. Nonlinear interactions give rise to an energy cascade towards smaller scales where energy is dissipated in an intermittent fashion. Due to the strong longitudinal magnetic field, dissipative structures propagate along the loop, with the typical speed of the Alfvén waves. The statistical analysis on the intermittent dissipative events compares well with all observed properties of nanoflare emission statistics. Moreover the recent observations of non thermal velocity measurements during flare occurrence are well described by the numerical results of the simulation model. All these results naturally emerge from the model dynamical evolution without any need of an ad-hoc hypothesis.
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Cranmer, Steven R., and Momchil E. Molnar. "Magnetohydrodynamic Mode Conversion in the Solar Corona: Insights from Fresnel-like Models of Waves at Sharp Interfaces." Astrophysical Journal 955, no. 1 (September 1, 2023): 68. http://dx.doi.org/10.3847/1538-4357/acee6c.
Abstract The solar atmosphere is known to contain many different types of wave-like oscillation. Waves and other fluctuations (e.g., turbulent eddies) are believed to be responsible for at least some of the energy transport and dissipation that heats the corona and accelerates the solar wind. Thus, it is important to understand the behavior of magnetohydrodynamic (MHD) waves as they propagate and evolve in different regions of the Sun’s atmosphere. In this paper, we investigate how MHD waves can affect the overall plasma state when they reflect and refract at sharp, planar interfaces in density. First, we correct an error in a foundational paper (Stein) that affects the calculation of wave energy-flux conservation. Second, we apply this model to reflection-driven MHD turbulence in the solar wind, where the presence of density fluctuations can enhance the generation of inward-propagating Alfvén waves. This model reproduces the time-averaged Elsässer imbalance fraction (i.e., the ratio of inward to outward Alfvénic power) from several published numerical simulations. Lastly, we model how the complex magnetic field threading the transition region (TR) between the chromosphere and corona helps convert a fraction of upward-propagating Alfvén waves into fast-mode and slow-mode MHD waves. These magnetosonic waves dissipate in a narrow region around the TR and produce a sharp peak in the heating rate. This newly found source of heating sometimes exceeds the expected heating rate from Alfvénic turbulence by an order of magnitude. It may explain why some earlier models seemed to require an additional ad hoc heat source at this location.
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Sharma, A. Y., M. D. J. Cole, T. Görler, Y. Chen, D. R. Hatch, W. Guttenfelder, R. Hager, et al. "Global gyrokinetic study of shaping effects on electromagnetic modes at NSTX aspect ratio with ad hoc parallel magnetic perturbation effects." Physics of Plasmas 29, no. 11 (November 2022): 112503. http://dx.doi.org/10.1063/5.0106925.
Plasma shaping may have a stronger effect on global turbulence in tight-aspect-ratio tokamaks than in conventional-aspect-ratio tokamaks due to the higher toroidicity and more acute poloidal asymmetry in the magnetic field. In addition, previous local gyrokinetic studies have shown that it is necessary to include parallel magnetic field perturbations in order to accurately compute growth rates of electromagnetic modes in tight-aspect-ratio tokamaks. In this work, the effects of elongation and triangularity on global, ion-scale, linear electromagnetic modes are studied at National Spherical Torus Experiment (NSTX) aspect ratio and high plasma β using the global gyrokinetic particle-in-cell code XGC. The effects of compressional magnetic perturbations are approximated via a well-known modification to the particle drifts that was developed for flux-tube simulations [Joiner et al., Phys. Plasmas 17, 072104 (2010)], without proof of its validity in a global simulation, with the gyrokinetic codes GENE and GEM being used for local verification and global cross-verification. Magnetic equilibria are re-constructed for each distinct plasma profile that is used. Coulomb collision effects are not considered. Within the limitations imposed by the present study, it is found that linear growth rates of electromagnetic modes (collisionless microtearing modes and kinetic ballooning modes) are significantly reduced in a high-elongation and high-triangularity NSTX-like geometry compared to a circular NSTX-like geometry. For example, growth rates of kinetic ballooning modes at high- β are reduced to the level of that of collisionless trapped electron modes.
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Baudoin, Camille, Patrick Tamain, Hugo Bufferand, Guido Ciraolo, Nicolas Fedorczak, Davide Galassi, Philippe Ghendrih, and Nicolas Nace. "Turbulent heat transport in TOKAM3X edge plasma simulations." Contributions to Plasma Physics 58, no. 6-8 (June 6, 2018): 484–89. http://dx.doi.org/10.1002/ctpp.201700168.
Rincon, François, Francesco Califano, Alexander A. Schekochihin, and Francesco Valentini. "Turbulent dynamo in a collisionless plasma." Proceedings of the National Academy of Sciences 113, no. 15 (March 29, 2016): 3950–53. http://dx.doi.org/10.1073/pnas.1525194113.
Magnetic fields pervade the entire universe and affect the formation and evolution of astrophysical systems from cosmological to planetary scales. The generation and dynamical amplification of extragalactic magnetic fields through cosmic times (up to microgauss levels reported in nearby galaxy clusters, near equipartition with kinetic energy of plasma motions, and on scales of at least tens of kiloparsecs) are major puzzles largely unconstrained by observations. A dynamo effect converting kinetic flow energy into magnetic energy is often invoked in that context; however, extragalactic plasmas are weakly collisional (as opposed to magnetohydrodynamic fluids), and whether magnetic field growth and sustainment through an efficient turbulent dynamo instability are possible in such plasmas is not established. Fully kinetic numerical simulations of the Vlasov equation in a 6D-phase space necessary to answer this question have, until recently, remained beyond computational capabilities. Here, we show by means of such simulations that magnetic field amplification by dynamo instability does occur in a stochastically driven, nonrelativistic subsonic flow of initially unmagnetized collisionless plasma. We also find that the dynamo self-accelerates and becomes entangled with kinetic instabilities as magnetization increases. The results suggest that such a plasma dynamo may be realizable in laboratory experiments, support the idea that intracluster medium turbulence may have significantly contributed to the amplification of cluster magnetic fields up to near-equipartition levels on a timescale shorter than the Hubble time, and emphasize the crucial role of multiscale kinetic physics in high-energy astrophysical plasmas.
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Gleize, Vincent, Michel Costes, and Ivan Mary. "Numerical simulation of NACA4412 airfoil in pre-stall conditions." International Journal of Numerical Methods for Heat & Fluid Flow 32, no. 4 (November 30, 2021): 1375–97. http://dx.doi.org/10.1108/hff-07-2021-0514.
Purpose The purpose of this paper is to study turbulent flow separation at the airfoil trailing edge. This work aims to improve the knowledge of stall phenomenon by creating a QDNS database for the NACA412 airfoil. Design/methodology/approach Quasi-DNS simulations of the NACA 4412 airfoil in pre-stall conditions have been completed. The Reynolds number based on airfoil chord and freestream velocity is equal to 0.35 million, and the freestream Mach number to 0.117. Transition is triggered on both surfaces for avoiding the occurrence of laminar separation bubbles and to ensure turbulent mixing in the wake. Four incidences have been considered, 5, 8 10 and 11 degrees. Findings The results obtained show a reasonably good correlation of the present simulations with classical MSES airfoil simulations and with RANS computations, both in terms of pressure and skin-friction distribution, with an earlier and more extended flow separation in the QDNS. The database thus generated will be deeply analysed and enriched for larger incidences in the future. Originality/value No experimental or HPC numerical database at reasonable Reynolds number exists in the literature. The current work is the first step in that direction.
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Timofeev, I. V., and A. V. Terekhov. "Simulations of turbulent plasma heating by powerful electron beams." Physics of Plasmas 17, no. 8 (August 2010): 083111. http://dx.doi.org/10.1063/1.3474952.
Timofeev, I. V., and A. V. Terekhov. "Simulations of Turbulent Plasma Heating by Powerful Electron Beams." Fusion Science and Technology 59, no. 1T (January 2011): 70–73. http://dx.doi.org/10.13182/fst11-a11577.
Kitiashvili, I. N., A. G. Kosovichev, A. A. Wray, and N. N. Mansour. "Realistic MHD simulations of magnetic self-organization in solar plasma." Proceedings of the International Astronomical Union 6, S274 (September 2010): 120–24. http://dx.doi.org/10.1017/s1743921311006703.
AbstractFilamentary structure is a fundamental property of the magnetized solar plasma. Recent high-resolution observations and numerical simulations have revealed close links between the filamentary structures and plasma dynamics in large-scale solar phenomena, such as sunspots and magnetic network. A new emerging paradigm is that the mechanisms of the filamentary structuring and large-scale organization are natural consequences of turbulent magnetoconvection on the Sun. We present results of 3D radiative MHD large-eddy simulations (LES) of magnetic structures in the turbulent convective boundary layer of the Sun. The results show how the initial relatively weak and uniformly distributed magnetic field forms the filamentary structures, which under certain conditions gets organized on larger scales, creating stable long-living magnetic structures. We discuss the physics of magnetic self-organization in the turbulent solar plasma, and compare the simulation results with observations.
Дисертації з теми "Simulations HPC de plasma turbulent":
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Manas, Pierre. "Gyrokinetic simulations of turbulent impurity transport in tokamaks." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4745/document.
La compréhension du transport d'impuretés dans le coeur des plasmas de tokamaks est un enjeu principal de la fusion par confinement magnétique. En effet les impuretés sont omni-présentes dans les tokamaks et leur présence dans le coeur a des effets négatifs sur le confinement du plasma (dilution, rayonnement). Récemment une attention particulière s'est portée sur le flux convectif turbulent dû au gradient de rotation toroïdale pour expliquer les profils plat/creux d'impuretés observés expérimentalement dans le coeur du plasma. Dans cette thèse une approche numérique a été adoptée avec l'utilisation entre autres de codes tels que NEO pour le transport néoclassique et GKW pour le transport turbulent, tout les deux incluant l'effet de la rotation toroïdale. Une comparaison du facteur de piquage du carbone (R/LnC) mesuré expérimentalement (dans le tokamak européen JET) et obtenu numériquement est faite pour un grand nombre de plasma en mode H (mode de confinement amélioré). La comparaison entre les mesures expérimentales de R/LnC et les résultats numériques donne lieu à deux constats. Premièrement la partie convective du flux correspondant au gradient de rotation toroïdale a un impact important sur R/LnC et principalement à valeurs élevées de ce gradient. Deuxièmement les simulations surestiment ce piquage dans le coeur du plasma où les profils expérimentaux sont creux. Ce désaccord, observé à haute collisionalité uniquement, est également obtenu pour le transport de moment ce qui pourrait être la signature d'un méchanisme de brisure de symmétrie (important pour le transport d'impureté et de moment) manquant Understanding impurity transport in the core of tokamak plasmas is central to achieving controlled fusion. Indeed impurities are ubiquitous in these devices and their presence in the core are detrimental to plasma confinement (fuel dilution, Bremsstrahlung). Recently, specific attention was given to the convective mechanism related to the gradient of the toroidal rotation to explain experimental flat/hollow impurity profiles in the plasma core. In this thesis, up-to-date modelling tools (NEO for neoclassical transport and GKW for turbulent transport) including the impact of toroidal rotation are used to study both the neoclassical and turbulent contributions to impurity fluxes. A comparison of the experimental and modelled carbon density peaking factor (R/LnC) is performed for a large number of baseline and hybrid H-mode plasmas (increased confinement regimes) with modest to high toroidal rotation from the European tokamak JET. Confrontation of experimental and modelled carbon peaking factor yields two main results. First roto-diffusion is found to have a nonnegligible impact on the carbon peaking factor at high values of the toroidal rotation frequency gradient. Second, there is a tendency to overpredict the experimental R/LnC in the core inner region where the carbon density profiles are hollow. This disagreement between experimental and modelled R/LnC, closely related to the collisionality, is also observed for the momentum transport channel which hints at a common parallel symmetry breaking mechanism lacking in the simulations
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Soe, Min. "Thermal lattice Boltzmann simulations of variable Prandtl number turbulent flow." W&M ScholarWorks, 1997. https://scholarworks.wm.edu/etd/1539623912.
With the advent of massively parallel processor machines, thermal lattice Boltzmann equation (TLBE) techniques offer an attractive way of handling turbulence simulations. TLBE is new form of DNS (direct numerical simulation method)--with the important advantages of being ideal for multi-parallel processors as well as being able to handle complicated geometries. Since there are many kinetic models that will reproduce the macroscopic nonlinear (compressible) transport equations, TLBE chooses that subset which can be readily solved on a discrete spatial lattice. The lattice geometry must be so chosen that the discrete phase representation of TLBE will not taint the rotational symmetric continuum equations. For 2D compressible flows, linear stability analyses described in this work indicates that the hexagonal lattice is optimum.;In nearly all lattice Boltzmann literature, the linearized Boltzmann collision operator has been taken to be the simple single-time Krook relaxation collision operator. This scalar collision operator is sufficient to recover the nonlinear transport equations under Chapmann-Enskog expansions. However, all previous LBE have suffered from the problem of density dependent transport coefficients. Even though this poses no problem for incompressible flows, it is critical and must be handled for compressible fluid simulations. The other deficiency of conventional TLBE scheme with single relaxation operator is that it only allows for fixed Prandtl number flow simulations.;In this work, to simulate flows with arbitrary Prandtl number, a matrix collision operator is introduced. With the inclusion of additional free parameter in the off-diagonal components, the scheme is now extended to a multi-relaxation process. This allows generalizations on relaxation parameters to produce density independent transport coefficients. Explicit solutions of TLBE are presented for 2D free decaying turbulence.
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Gracio, Bilro Castela Maria Luis. "Direct Numerical Simulations of plasma-assisted ignition in quiescent and turbulent flow conditions." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC042/document.
La combustion assistée par plasma a reçu une attention croissante dans les deux communautés de plasma et de combustion. Les décharges Nanoseconde Répétitive Pulsée (NRP) sont des techniques prometteuse et efficaces pour initier et contrôler les processus de la combustion en particulier quand les systèmes d’allumage conventionnels sont inefficaces ou trop coûteux en énergie. Néanmoins, les phénomènes rencontrés dans la combustion assistée par plasma sont encore mal connus. Les études numériques présentées dans la littérature sont limitées à des simulations 1-D et 2-D dans des conditions au repos. La complexité du problème augmente dans les configurations pratiques où le phénomène d’allumage est contrôlé par le mouvement du fluide ainsi que le mélange autour de la zone de décharge. La simulation numérique directe (DNS) est un outil de recherche puissant pour la compréhension des interactions plasma/combustion/écoulement. Toutefois, le coût de calcul de la combustion turbulente avec un nombre de Reynolds élevé et la cinétique chimique détaillée couplée avec le plasma hors-équilibre est prohibitif. Cette thèse présente un nouveau modèle de couplageplasma-combustion pour introduire les effets des décharges de plasma hors-équilibre dans le système d’équations qui décrit le phénomène de la combustion. Le modèle est construit en analysant les chemins par lesquels l’énergie électrique est transférée au gaz. Ce modèle de décharges NRP permet des simulations multidimensionalesDNS de la combustion et l’allumage assistés par plasma. Les phénomènes physiques complexes de l’allumage assisté par décharges multiples de plasma dans des mélanges au repos et en régime d’écoulement turbulent sont analysés dans cette thèse Plasma-assisted combustion has received increasing attention in both plasma and combustion communities. Nanosecond Repetitively Pulsed (NRP) discharges are a promising and efficient technique to initiate and control combustion processes particularly when conventional ignition systems are rather ineffective or too energy costly. Even though a promising technique, the phenomena occurring in NRP discharges-assisted combustion are still poorly understood. The numerical studies presented in the literature are limited to 1-D and 2-D simulations in quiescent conditions. The problem complexity increases in practical configurations as ignition phenomena are also controlled by the flow and mixing field characteristics in and around the discharge channel. Direct Numerical Simulations (DNS) is a powerful research tool to understand these plasma/combustion/flow interactions. However, the computational cost of fully coupled detailed non-equilibrium plasma and combustion chemistry, and high Reynolds number simulations is prohibitive. This thesis presents a model to describe the effects of non-equilibrium plasma discharges in the set of equations governing the combustion phenomena. Based on the results reported in the literature, the model is constructed by analyzing the channels through which the electric energy is deposited. The two main channels by which the electrons produced during the discharge impact the reactive mixture are considered: 1) the excitation and the subsequent relaxation of the electronic states of nitrogen molecules, which leads to an ultrafast increase of the gas temperature and dissociation of species; and 2) the excitation and relaxation of vibrational states of nitrogen molecules which causes a much slower gas heating. This high level model of NRP discharges allows DNS studies of plasma-assisted combustion / ignition in high turbulent Reynolds number. The complex physics underlying plasma-assisted ignition by multiple discharges in both quiescent and turbulent flow conditions are discussed in the present thesis
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Colin, Clothilde. "Turbulent transport modeling in the edge plasma of tokamaks : verification, validation, simulation and synthetic diagnostics." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4350/document.
La possibilité de produire de l'énergie en utilisant la fusion par confinement magnétique est un défi scientifique et technologique. La perspective d'ITER transmet des signaux forts afin d'intensifier les efforts de modélisation pour les plasmas de fusion. Le succès de la fusion est conditionnée par la qualité du confinement du plasma dans le cœur du réacteur et par le contrôle des flux de particules et de chaleur qui arrivent sur la paroi. Les deux phénomènes sont liés au transport turbulent. L'étude de ces phénomènes est d'autant plus compliquée que la géométrie magnétique est complexe. Cela nécessite une amélioration de notre capacité à développer des outils numériques capables de reproduire les propriétés du transport turbulent fiables.Cette thèse présente le modèle fluide du code TOKAM3X pour simuler plasma de bord turbulent. Une attention particulière a été portée sur la vérification et la validation de ce code, ce qui est une étape nécessaire avant d'utiliser un code comme un outil prédictif. Ensuite, de nouvelles études sur les propriétés physiques de la turbulence bord du plasma sont examinées. En particulier, les asymétries poloïdales induites par la turbulence et observées expérimentalement côté faible champ sont étudiées en détail. Un grand soin est dédié à la reproduction du scénario MISTRAL, qui consiste à changer la configuration magnétique et à en observer l'impact sur les flux parallèles dans le plan poloïdal. Les simulations reproduisent les mesures expérimentales et fournissent de nouvelles informations sur l'effet du point de contact plasma-paroi sur les caractéristiques de la turbulence, qui ne sont pas accessibles dans les expériences The possibility to produce power by using magnetically confined fusion is a scientific and technological challenge. The perspective of ITER conveys strong signals to intensify modeling effort on magnetized fusion plasmas. The success of the fusion operation is conditioned by the quality of plasma confinement in the core of the reactor and by the control of plasma exhaust on the wall. Both phenomena are related to turbulent cross-field transport that is at the heart of the notion of magnetic confinement studies, particle and heat losses. The study of edge phenomena is therefore complicated by a particularly complex magnetic geometry.This calls for an improvement of our capacity to develop numerical tools able to reproduce turbulent transport properties reliable to predict particle and energy fluxes on the plasma facing components. This thesis introduces the TOKAM3X fluid model to simulate edge plasma turbulence. A special focus is made on the code Verification and the Validation. It is a necessary step before using a code as a predictive tool. Then new insights on physical properties of the edge plasma turbulence are explored. In particular, the poloidal asymmetries induced by turbulence and observed experimentally in the Low-Field-Side of the devices are investigated in details. Great care is dedicated to the reproduction of the MISTRAL base case which consists in changing the magnetic configuration and observing the impact on parallel flows in the poloidal plane. The simulations recover experimental measurements and provide new insights on the effect of the plasma-wall contact position location on the turbulent features, which were not accessible in experiments
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Lalescu, Cristian. "Test particle transport in turbulent magnetohydrodynamic structures." Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209908.
Turbulent phenomena are found in both natural (e.g. the Earth's oceans, the Sun's corona) and artificial (e.g. flows through pipes, the plasma in a tokamak device) settings; evidence suggests that turbulence is usually the normal behaviour in most cases. Turbulence has been studied extensively for more than a century, but a complete and consistent theoretical description of it has not yet been proposed. It is in this context that the motion of particles under the influence of turbulent fields is studied in this work, with direct numerical simulations. The thesis is structured in three main parts. The first part describes the tools that are used. Methods of integrating particle trajectories are presented, together with a discussion of the properties that these methods should have. The simulation of magnetohydrodynamic (MHD) turbulence is discussed, while also introducing fundamental concepts of fluid turbulence. Particle trajectory integration requires information that is not readily available from simulations of turbulent flows, so the interpolation methods needed to adapt the fluid simulation results are constructed as well. The second part is dedicated to the study of two MHD problems. Simulations of Kolmogorov flow in incompressible MHD are presented and discussed, and also simulations of the dynamo effect in compressible MHD. These two scenarios are chosen because large scale structures are formed spontaneously by the turbulent flow, and there is an interest in studying particle transport in the presence of structures. Studies of particle transport are discussed in the third part. The properties of the overall approach are first analyzed in detail, for stationary predefined fields. Focus is placed on the qualitative properties of the different methods presented. Charged article transport in frozen turbulent fields is then studied. Results concerning transport of particles in fully developed, time-evolving, turbulent fields are presented in the final chapter.
\ Doctorat en Sciences info:eu-repo/semantics/nonPublished
Частини книг з теми "Simulations HPC de plasma turbulent":
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Coroniti, F. V. "Space Plasma Turbulent Dissipation: Reality or Myth?" In Space Plasma Simulations, 399–410. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5454-0_24.
Lewandowski, J. L. V., W. W. Lee, and Z. Lin. "Gyrokinetic Simulations of Plasma Turbulence on Massively Parallel Computers." In High Performance Computing — HiPC 2001, 95–103. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/3-540-45307-5_9.
Gondarenko, N. A., and P. N. Guzdar. "Structure of turbulent irregularities in high-latitude plasma patches-3D nonlinear simulations." In Disturbances in Geospace: The Storm-Substorm Relationship, 205–15. Washington, D. C.: American Geophysical Union, 2003. http://dx.doi.org/10.1029/142gm17.
Lago, Rafael, Michael Obersteiner, Theresa Pollinger, Johannes Rentrop, Hans-Joachim Bungartz, Tilman Dannert, Michael Griebel, Frank Jenko, and Dirk Pflüger. "EXAHD: A Massively Parallel Fault Tolerant Sparse Grid Approach for High-Dimensional Turbulent Plasma Simulations." In Software for Exascale Computing - SPPEXA 2016-2019, 301–29. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-47956-5_11.
Тези доповідей конференцій з теми "Simulations HPC de plasma turbulent":
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Tskhakaya, David, Alejandro Soba, Ralf Schneider, Mattias Borchardt, Erven Yurtesen, and Jan Westerholm. "PIC/MC Code BIT1 for Plasma Simulations on HPC." In 2010 18th Euromicro International Conference on Parallel, Distributed and Network-Based Processing (PDP). IEEE, 2010. http://dx.doi.org/10.1109/pdp.2010.47.
Reynolds-Barredo, J. M., D. E. Newman, J. M. Reynolds-Barredo, R. Sanchez, and L. A. Berry. "Modelling parareal convergence in 2D drift wave plasma turbulence." In 2012 International Conference on High Performance Computing & Simulation (HPCS). IEEE, 2012. http://dx.doi.org/10.1109/hpcsim.2012.6267004.
JOU, W. H., and JAMES RILEY. "On direct numerical simulations of turbulent reacting flows." In 19th AIAA, Fluid Dynamics, Plasma Dynamics, and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1987. http://dx.doi.org/10.2514/6.1987-1324.
Joiner, Nathan, Akira Hirose, and William Dorland. "Gyrokinetic simulation of micro-turbulence in magnetically confined plasmas." In 21st International Symposium on High Performance Computing Systems and Applications (HPCS'07). IEEE, 2007. http://dx.doi.org/10.1109/hpcs.2007.18.
Shaikh, Dastgeer, G. P. Zank, M. Maksimovic, K. Issautier, N. Meyer-Vernet, M. Moncuquet, and F. Pantellini. "Self-consistent Simulations of Plasma-Neutral in a Partially Ionized Astrophysical Turbulent Plasma." In TWELFTH INTERNATIONAL SOLAR WIND CONFERENCE. AIP, 2010. http://dx.doi.org/10.1063/1.3395827.
Glimm, J., and Xiaolin Li. "Validation of Rayleigh-Taylor turbulent mixing simulations for real fluids." In The 33rd IEEE International Conference on Plasma Science, 2006. ICOPS 2006. IEEE Conference Record - Abstracts. IEEE, 2006. http://dx.doi.org/10.1109/plasma.2006.1707008.
Mullenix, Nathan, Datta Gaitonde, and Miguel Visbal. "A Plasma-Actuator-Based Method to Generate a Supersonic Turbulent Boundary Layer Inflow Condition for Numerical Simulations." In 20th AIAA Computational Fluid Dynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2011. http://dx.doi.org/10.2514/6.2011-3556.
Cambareri, Joseph J., and Igor A. Bolotnov. "Interface Tracking Simulations of Two-Phase Flow Utilizing Adaptive Meshing Capabilities." In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-81247.
Due to the increase of computing efficiency and power, full-resolution two-phase flow simulations have become a practical research tool for model development and analysis of reactor flows. The expansion of state-of-the-art high performance computing (HPC) facilities allows for the use of direct numerical simulation (DNS) coupled with Interface Tracking Methods (ITM) to perform full resolution simulations. Given adequate spatial and temporal resolution, DNS can resolve all relevant turbulent scales, allowing for the extraction of high quality and detailed turbulent and two-phase flow numerical data for use in model development. While larger scale bubbly flow DNS are becoming ever more affordable, it is still computationally expensive due to the requirements of the spatial discretization. This presents the largest obstacle for future applications of DNS. For this reason, mesh adaptation techniques are sought after to reduce the computational expense of bubbly flow simulations in complex geometries. By fully resolving only the areas of specific interest, the computational costs of DNS can be reduced. Grid refinement can be based on the location of the interface between the two phases, area of greatest turbulent intensity, averaged bulk fluid velocity data, or the prediction of bubble movement. Coupled with an advanced bubble tracking algorithm, the path of individual bubbles moving through the computational domain can be predicted, and the computational mesh refined within the path area. This refinement can create tracks of greater resolution for the bubbles to move through in the domain, while keeping the bulk resolution of the mesh coarser. Through these means, the overall cost of the simulation is reduced, while high quality numerical data is still obtainable. This work outlines the enhancement of existing mesh adaptation algorithms to implement the bubble tracking refinement, and its practical applications to full resolution two-phase flow simulations.
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Vasilopoulos, Ilias, Paolo Adami, Matthias Voigt, Marcus Meyer, and Ronald Mailach. "Roughness Investigations on In-Service High-Pressure Compressor Blades – Part II: Roughness Parameterization and CFD-Based Modelling of its Impact on Turbulent Flows." In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-101157.
Abstract The two-part publication deals with roughness investigations on in-service high-pressure compressor (HPC) blades, both in terms of measurements and simulations. In this paper (Part II), first, stripe measurements of surface roughness coming from the suction side of the blades are conducted, using a highly accurate Alicona measuring device (see Part I for details of the measurement approach). Then, these roughness distributions are used to construct the walls of zero-pressure-gradient, fully turbulent channel flow simulations. Body-fitted unstructured grids of up to 80M nodes are generated, on which wall-resolved LES as well as RANS simulations with the k-ω SST turbulence model are performed. The CFD setup is first validated on a smooth channel reference case against LES and DNS data from the relevant literature. In addition, the impact of Reynolds number on several rough channel flow simulations is explored, using two different setups at Reτ = 540 and Reτ = 880. Finally, after an identification of the most important roughness parameters (given the relatively limited database at hand), a new roughness function model is proposed, which would allow the prediction of the flow over a rough surface without the need of geometrically resolving the roughness scales.
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Sreeyasunath, S., and E. Y. K. Ng. "Prediction of High Pressure Axial Compressor Stage Flow Using a Circumferential Average Approach." In ASME 1997 Turbo Asia Conference. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-aa-011.
A solver for compressible turbulent flow has been developed for a single stage environment. The current work presents the results of numerical simulations of ‘proposed high pressure compressor’ (HPC) using an exact geometry dimensions with full flow conditions. The flow solver is based on the Reynolds averaged Navier-Stokes (RNS) equations in which the algebraic Baldwin-Lomax model is adopted. This numerical scheme simulates the steady flow phenomena of stator-rotor interaction in single stage environment. The numerical method used in the solver serves as a basis for many CFD works in the group. The accurate numerical analysis of complex flows associated with stator/rotor configurations in turbomachinery can be very helpful for understanding the flow phenomena. A comprehensive and satisfactory theoretical prediction of the whole process of blade row interaction will only be available when viscous and mixing effects can be taken into account numerically. The current analysis is used to predict the convective heat transfer on the suction and pressure surfaces of the ‘proposed HPC’.
Звіти організацій з теми "Simulations HPC de plasma turbulent":
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Theilhaber, K., G. Laval, and D. Pesme. Numerical Simulations of Turbulent Trapping in the Weak Beam-Plasma Instability. Fort Belvoir, VA: Defense Technical Information Center, June 1986. http://dx.doi.org/10.21236/ada170108.
