Thematische Bibliographien / Schéma de Splitting

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Auswahl der wissenschaftlichen Literatur zum Thema „Schéma de Splitting“

Autor: Grafiati

Veröffentlicht am 30. November 2024

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Zeitschriftenartikel zum Thema "Schéma de Splitting"

Lai, Junjiang, und Zhencheng Fan. „Stability for discrete time waveform relaxation methods based on Euler schemes“. AIMS Mathematics 8, Nr. 10 (2023): 23713–33. http://dx.doi.org/10.3934/math.20231206.

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<abstract><p>Stability properties of discrete time waveform relaxation (DWR) methods based on Euler schemes are analyzed by applying them to two dissipative systems. Some sufficient conditions for stability of the considered methods are obtained; at the same time two examples of instability are given. To investigate the influence of the splitting functions and underlying numerical methods on stability of DWR methods, DWR methods based on different splittings and different numerical schemes are considered. The obtained results show that the stabilities of waveform relaxation methods based on an implicit Euler scheme are better than those based on explicit Euler scheme, and that the stabilities of waveform relaxation methods based on the classical splittings such as Gauss-Jacobi and Gauss-Seidel splittings are worse than those based on the eigenvalue splitting presented in this paper. Finally, numerical examples that confirm the theoretical results are presented.</p></abstract>

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Shin, Sang-Mook, In-Chul Kim und Yong-Jig Kim. „Numerical Simulation of Free Surface Flows Using the Roe's Flux-difference Splitting Scheme“. Journal of the Society of Naval Architects of Korea 47, Nr. 1 (20.02.2010): 11–19. http://dx.doi.org/10.3744/snak.2010.47.1.011.

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Liou, Meng-Sing, und Christopher J. Steffen. „A New Flux Splitting Scheme“. Journal of Computational Physics 107, Nr. 1 (Juli 1993): 23–39. http://dx.doi.org/10.1006/jcph.1993.1122.

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Lai, J. S., G. F. Lin und W. D. Guo. „Simulation of Hydraulic Shock Waves by Hybrid Flux-Splitting Schemes in Finite Volume Method“. Journal of Mechanics 21, Nr. 2 (Juni 2005): 85–101. http://dx.doi.org/10.1017/s1727719100004561.

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AbstractIn the framework of the finite volume method, a robust and easily implemented hybrid flux-splitting finite-volume (HFF) scheme is proposed for simulating hydraulic shock waves in shallow water flows. The hybrid flux-splitting algorithm without Jacobian matrix operation is established by applying the advection upstream splitting method to estimate the cell-interface fluxes. The scheme is extended to be second-order accurate in space and time using the predictor-corrector approach with monotonic upstream scheme for conservation laws. The proposed HFF scheme and its second-order extension are verified through simulations of the 1D idealized dam-break problem, the 2D oblique hydraulic shock-wave problem, and the 2D dam-break experiments with channel contraction as well as wet/dry beds. Comparisons of the HFF and several well-known first-order upwind schemes are made to evaluate numerical performances. It is demonstrated that the HFF scheme captures the discontinuities accurately and produces no entropy-violating solutions. The HFF scheme and its second-order extension are proven to achieve the numerical benefits combining the efficiency of flux-vector splitting scheme and the accuracy of flux-difference splitting scheme for the simulation of hydraulic shock waves.

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Tang, Yuru, Chen Chen, Min Liu, Pengfei Du und H. Y. Fu. „Rate-Splitting-Based Generalized Multiple Access for Band-Limited Multi-User VLC“. Photonics 10, Nr. 4 (13.04.2023): 446. http://dx.doi.org/10.3390/photonics10040446.

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In this paper, we propose a rate-splitting-based generalized multiple access (GMA) scheme for band-limited multi-user visible light communication (VLC) systems. By splitting and transmitting the input data of each user in a joint orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) manner, the proposed rate-splitting-based GMA scheme can obtain better bandwidth utilization than OMA and suffer less severe interference than NOMA. In order to achieve the maximum sum rate over typical low-pass VLC channels, the optimal rate-splitting-based GMA scheme was first obtained through theoretical analysis and computer simulations. Subsequently, the superiority of the optimal rate-splitting-based GMA scheme over both OMA and NOMA under various channel conditions, user separations, and error propagation levels was further verified by the theoretical, simulation, and experimental results. In particular, the experimental results showed that, when the error propagation ratio was increased from 0 to 0.2, the sum rate reduction ratio was significantly reduced from 31.4% to 7.5% by replacing NOMA with the obtained optimal rate-splitting-based GMA.

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Xia, Cheng Jun, Cui Qiong Chen, Kun Men und Ji Xue Yan. „A Novel System Splitting Scheme Based on the Identification of Weak Connection“. Advanced Materials Research 1008-1009 (August 2014): 473–79. http://dx.doi.org/10.4028/www.scientific.net/amr.1008-1009.473.

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In this paper, a new system splitting scheme based on the identification of weak connection is proposed. This paper firstly claims that if two nodes in a transmission line are related to two different generator groups or irrelated to any generator group, the transmission line is regarded as weak connection. And matrix R is presented to reflect the relevance between load nodes and generator groups after faults are cleared. The candidate strategy space is composed of these transmission lines of weak connection. Secondly, the procedure of searching the splitting surfaces is listed to illustrate how the splitting scheme works. Finally IEEE 39-bus system is used to verify the feasibility of this splitting scheme.

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Lee, Hyun Geun, Jaemin Shin und June-Yub Lee. „A High-Order Convex Splitting Method for a Non-Additive Cahn–Hilliard Energy Functional“. Mathematics 7, Nr. 12 (16.12.2019): 1242. http://dx.doi.org/10.3390/math7121242.

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Various Cahn–Hilliard (CH) energy functionals have been introduced to model phase separation in multi-component system. Mathematically consistent models have highly nonlinear terms linked together, thus it is not well-known how to split this type of energy. In this paper, we propose a new convex splitting and a constrained Convex Splitting (cCS) scheme based on the splitting. We show analytically that the cCS scheme is mass conserving and satisfies the partition of unity constraint at the next time level. It is uniquely solvable and energy stable. Furthermore, we combine the convex splitting with the specially designed implicit–explicit Runge–Kutta method to develop a high-order (up to third-order) cCS scheme for the multi-component CH system. We also show analytically that the high-order cCS scheme is unconditionally energy stable. Numerical experiments with ternary and quaternary systems are presented, demonstrating the accuracy, energy stability, and capability of the proposed high-order cCS scheme.

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Bréhier, Charles-Edouard, Jianbo Cui und Jialin Hong. „Strong convergence rates of semidiscrete splitting approximations for the stochastic Allen–Cahn equation“. IMA Journal of Numerical Analysis 39, Nr. 4 (30.07.2018): 2096–134. http://dx.doi.org/10.1093/imanum/dry052.

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Abstract This article analyses an explicit temporal splitting numerical scheme for the stochastic Allen–Cahn equation driven by additive noise in a bounded spatial domain with smooth boundary in dimension $d\leqslant 3$. The splitting strategy is combined with an exponential Euler scheme of an auxiliary problem. When $d=1$ and the driving noise is a space–time white noise we first show some a priori estimates of this splitting scheme. Using the monotonicity of the drift nonlinearity we then prove that under very mild assumptions on the initial data this scheme achieves the optimal strong convergence rate $\mathcal{O}(\delta t^{\frac 14})$. When $d\leqslant 3$ and the driving noise possesses some regularity in space we study exponential integrability properties of the exact and numerical solutions. Finally, in dimension $d=1$, these properties are used to prove that the splitting scheme has a strong convergence rate $\mathcal{O}(\delta t)$.

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Li, Wanling, und Gengjun Gao. „Research on Multi-product Order Splitting and Distribution Route Optimization Of "Multi-warehouse in One Place"“. Frontiers in Business, Economics and Management 8, Nr. 3 (20.04.2023): 1–8. http://dx.doi.org/10.54097/fbem.v8i3.7449.

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In recent years, large online supermarkets have become a new trend in the development of e-commerce. Due to the limited storage capacity of a single warehouse, many large online supermarkets, such as Jingdong and Tmall, often adopt the warehouse layout of "one place and multiple warehouses" to quickly respond to customer needs, and the sorting and distribution tasks of orders are completed by the warehouse. At the same time, due to the change of people's lifestyle, customer demand presents the characteristics of "one order with multiple products" and "one order with multiple quantities", which makes the split fulfillment of orders become a common phenomenon. In this paper, under the condition that the warehouse is not out of stock in the layout of one place and many warehouses, aiming at the split execution problem of multi-category orders, the split order method is based on the combination of "minimum split order rate" and "principle of proximity". An order splitting optimization model considering both category and quantity splitting is established, and a set of initial order batch splitting schemes is formed to achieve the first optimization of multi-category order splitting. Secondly, the PLBH-LNS method is used to generate a better initial distribution scheme considering the customer preset time window limit and vehicle-mounted capacity constraint. Finally, with the goal of minimizing the total order performance cost, the solution idea of two-stage method is used for reference, based on the initial order splitting scheme and distribution scheme, the improved two-stage genetic algorithm is used to generate the optimal order allocation scheme and distribution scheme from the alternative schemes, and the global optimization of the splitting and distribution process is realized. The experimental results show that compared with the order splitting strategy using simple rules in practice, the PLBH-LNS method can reduce the average order splitting cost by 12.48%, which provides a new idea and effective auxiliary decision support for the order splitting problem of large online supermarkets.

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Ren, Yifei, und Zhiqiang Lu. „A flexible resource investment problem based on project splitting for aircraft moving assembly line“. Assembly Automation 39, Nr. 4 (02.09.2019): 532–47. http://dx.doi.org/10.1108/aa-09-2018-0126.

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Purpose In response to the station design and flexible resources allocation of the aircraft moving assembly line, a new problem named flexible resource investment problem based on project splitting (FRIP_PS), which minimizes total cost of resources with a given deadline are proposed in this paper. Design/methodology/approach First, a corresponding mathematical model considering project splitting is constructed, which needs to be simultaneously determined together with job scheduling to acquire the optimized project scheduling scheme and resource configurations. Then, an integrated nested optimization algorithm including project splitting policy and job scheduling policy is designed in this paper. In the first stage of the algorithm, a heuristic algorithm designed to get the project splitting scheme and then in the second stage a genetic algorithm with local prospective scheduling strategy is adopted to solve the flexible resource investment problem. Findings The heuristic algorithm of project splitting gets better project splitting results through the job shift selection strategy and meanwhile guides the algorithm of the second stage. Furthermore, the genetic algorithm solves resources allocation and job schedule through evaluation rules which can effectively solve the delayed execution of jobs because of improper allocation of flexible resources. Originality/value This paper represents a new extension of the resource investment problem based on aircraft moving assembly line. An effective integrated nested optimization algorithm is proposed to specify station splitting scheme, job scheduling scheme and resources allocation in the assembly lines, which is significant for practical engineering applications.

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Dissertationen zum Thema "Schéma de Splitting"

Bensaid, Bilel. „Analyse et développement de nouveaux optimiseurs en Machine Learning“. Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0218.

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Ces dernières années, l’intelligence artificielle (IA) est confrontée à deux défis majeurs (parmi d’autres), à savoir l’explicabilité et la frugalité, dans un contexte d’intégration de l’IA dans des systèmes critiques ou embarqués et de raréfaction des ressources. Le défi est d’autant plus conséquent que les modèles proposés apparaissent commes des boîtes noires étant donné le nombre faramineux d’hyperparamètres à régler (véritable savoir-faire) pour les faire fonctionner. Parmi ces paramètres, l’optimiseur ainsi que les réglages qui lui sont associés ont un rôle critique dans la bonne mise en oeuvre de ces outils [196]. Dans cette thèse, nous nous focalisons sur l’analyse des algorithmes d’apprentissage/optimiseurs dans le contexte des réseaux de neurones, en identifiant des propriétés mathématiques faisant écho aux deux défis évoqués et nécessaires à la robustesse du processus d’apprentissage. Dans un premier temps, nous identifions des comportements indésirables lors du processus d’apprentissage qui vont à l’encontre d’une IA explicable et frugale. Ces comportements sont alors expliqués au travers de deux outils: la stabilité de Lyapunov et les intégrateurs géométriques. Empiriquement, la stabilisation du processus d’apprentissage améliore les performances, autorisant la construction de modèles plus économes. Théoriquement, le point de vue développé permet d’établir des garanties de convergence pour les optimiseurs classiquement utilisés dans l’entraînement des réseaux. La même démarche est suivie concernant l’optimisation mini-batch où les comportements indésirables sont légions: la notion de splitting équilibré est alors centrale afin d’expliquer et d’améliorer les performances. Cette étude ouvre la voie au développement de nouveaux optimiseurs adaptatifs, issus de la relation profonde entre optimisation robuste et schémas numériques préservant les invariants des systèmes dynamiques
Over the last few years, developping an explainable and frugal artificial intelligence (AI) became a fundamental challenge, especially when AI is used in safety-critical systems and demands ever more energy. This issue is even more serious regarding the huge number of hyperparameters to tune to make the models work. Among these parameters, the optimizer as well as its associated tunings appear as the most important leverages to improve these models [196]. This thesis focuses on the analysis of learning process/optimizer for neural networks, by identifying mathematical properties closely related to these two challenges. First, undesirable behaviors preventing the design of explainable and frugal networks are identified. Then, these behaviors are explained using two tools: Lyapunov stability and geometrical integrators. Through numerical experiments, the learning process stabilization improves the overall performances and allows the design of shallow networks. Theoretically, the suggested point of view enables to derive convergence guarantees for classical Deep Learning optimizers. The same approach is valuable for mini-batch optimization where unwelcome phenomenons proliferate: the concept of balanced splitting scheme becomes essential to enhance the learning process understanding and improve its robustness. This study paves the way to the design of new adaptive optimizers, by exploiting the deep relation between robust optimization and invariant preserving scheme for dynamical systems

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Tang, Kunkun. „Combining Discrete Equations Method and Upwind Downwind-Controlled Splitting for Non-Reacting and Reacting Two-Fluid Computations“. Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00819824.

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Lors que nous examinons numériquement des phénomènes multiphasiques suite à un accidentgrave dans le réacteur nucléaire, la dimension caractéristique des zones multi-fluides(non-réactifs et réactifs) s'avère beaucoup plus petite que celle du bâtiment réacteur, cequi fait la Simulation Numérique Directe de la configuration à peine réalisable. Autrement,nous proposons de considérer la zone de mélange multiphasique comme une interface infinimentfine. Puis, le solveur de Riemann réactif est inséré dans la Méthode des ÉquationsDiscrètes Réactives (RDEM) pour calculer le front de combustion à grande vitesse représentépar une interface discontinue. Une approche anti-diffusive est ensuite couplée avec laRDEM afin de précisément simuler des interfaces réactives. La robustesse et l'efficacité decette approche en calculant tant des interfaces multiphasiques que des écoulements réactifssont à la fois améliorées grâce à la méthode ici proposée : upwind downwind-controlled splitting(UDCS). UDCS est capable de résoudre précisément des interfaces avec les maillagesnon-structurés multidimensionnels, y compris des fronts réactifs de détonation et de déflagration.

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Demange, Jérémie. „Schémas numériques d'advection et de propagation d'ondes de gravité dans les modèles de circulation océanique“. Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENM096/document.

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Les modèles numériques d'océans régionaux tridimensionnels sont basés sur la résolution des équations primitives et utilisent pour la plupart des méthodes de résolution eulérienne de type différences finies sur des grilles décalées. Ces modèles doivent représenter fidèlement les transports et transferts d'énergie. L'amélioration de ces modèles numériques exige donc (i) l'identification des processus prépondérants, notamment en terme de dissipation, dans ces transferts et (ii) la construction de méthodes numériques respectant un certain nombre d'équilibres. La première partie du travail se concentre sur la propagation des ondes externes et internes de gravité. Nous nous intéresserons en premier lieu à la stabilité de la séparation en mode rapide (barotrope) et lents (baroclines) et montrons qu'elle peut être ameliorée en levant certaines hypothèses traditionnellement effectuées. Dans un second temps, nous étudions l'impact de la discrétisation (ordre des schémas, grilles décalées ou non) sur la propagation des ondes internes de gravité provenant du couplage vitesse pression. Une décomposition en modes verticaux nous permet également de proposer un schéma espace temps très efficace. La seconde partie étudie en détail les schémas d'advection de quantité de mouvement et de traceurs, tout particulièrement dans l'objectif d'une réduction de la diffusion diapycnale (diffusion dans les directions orthogonales aux couches de densité constante). Ce travail nous amène tout d'abord à porter notre attention sur les schémas d'advection verticaux souvent négligés au regard de la dimension horizontale. Les bonnes propriétés d'un schéma compact (et de ses variantes espace temps et monotones) sont mises en avant. Enfin nous analysons le comportement multidimensionnel de ces schémas d'advection
Three-dimensional regional ocean numerical models are based on solving the primitive equations and mostly use Eulerian finite differences methods of resolution on staggered grids. These models must accurately represent transports and energy transfers. Improving these numerical models therefore requires (i) the identification of predominant process, particularly in terms of dissipation in these transfers and (ii) the construction of numerical methods respecting a number of balances. The first part of the work focuses on the propagation of external and internal gravity waves. We focus primarily on the stability of the separation in fast mode (barotropic) and slow (baroclinic) and show that it can be improved by removing certain assumptions traditionally made. In a second step, we study the impact of the discretization (order of schemes, staggered grids or not) on the propagation of internal gravity waves coming from the coupling velocity pressure. A decomposition into vertical modes also allows us to offer a highly effective space-time scheme. The second part examines in detail the numerical advection schemes of momentum and tracers, especially with the aim of reducing the diapycnal diffusion (diffusion in the orthogonal direction of constant density layers). This work leads us first to focus our attention on the vertical advection schemes often overlooked in front of the horizontal dimension. The good properties of a compact schema (and its space-time and monotonous variants ) are highlighted. Finally we analyze the multidimensional behavior of these advection schemes

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Caro, Florian. „Modélisation et simulation numérique des transitions de phase liquide vapeur“. Phd thesis, Ecole Polytechnique X, 2004. http://pastel.archives-ouvertes.fr/pastel-00000993.

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Ce travail de thèse est consacré à la modélisation et à la simulation numérique des transitions de phase liquide-vapeur. L'étude effectuée se découpe en deux randes parties: une première où on étudie les phénomènes de transition de phase avec une loi d'état de type Van Der Waals (perte de monotonie de la loi d'état) et une deuxième partie où on choisit une approche alternative avec deux loi d'états. La première partie consiste à étudier les critères visqueux classiques de sélection des solutions du système d'équations utilisé lorsque la loi d'état n'est pas monotone. Les critères classiques ne sélectionnant pas des solutions a priori physiques, un critère plus récent est introduit: le critère visco-capillaire. L'utilisation de ce critère avec un solveur de Riemann exact (sous la contrainte de trouver le zéro d'une fonction non linéaire) permet d'obtenir des résultats mais avec un coût de calcul trop élevé. Une approche alternative est alors envisagée avec deux lois d'états (une pour chaque phase). A l'aide d'un procédé de minimisation de l'action hamiltonienne, un modèle bifluide de changement de phase est proposé. Celui-ci respecte alors le second principe de la thermodynamique. Deux sous-systèmes en sont déduits à l'aide d'un procédé de retour à l'équilibre: mécanique dans un premier temp puis mécanique et thermodynamique dans un deuxième temps. Malgré la faible hyperbolicité du dernier sous-système obtenu, des schémas numériques stables basés sur une méthode de splitting sont proposés. On montre alors que le système ainsi obtenu est naturellement capable de nucléer des bulles de vapeur dans du liquide.

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Kularathna, Shyamini. „Splitting solution scheme for material point method“. Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274140.

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Material point method (MPM) is a numerical tool which was originally used for modelling large deformations of solid mechanics problems. Due to the particle based spatial discretiza- tion, MPM is naturally capable of handling large mass movements together with topological changes. Further, the Lagrangian particles in MPM allow an easy implementation of history dependent materials. So far, however, research on MPM has been mostly restricted to explicit dynamic formu- lations with linear approximation functions. This is because of the simplicity and the low computational cost of such explicit algorithms. Particularly in MPM analysis of geomechan- ics problems, a considerable attention is given to the standard explicit formulation to model dynamic large deformations of geomaterials. Nonetheless, several limitations exist. In the limit of incompressibility, a significantly small time step is required to ensure the stability of the explicit formulation. Time step size restriction is also present in low permeability cases in porous media analysis. Spurious pressure oscillations are another numerical instability present in nearly incompressible flow behaviours. This research considers an implicit treatment of the pressure in MPM algorithm to simu- late material incompressibility. The coupled velocity (v)-pressure (p) governing equations are solved by applying Chorin’s projection method which exhibits an inherent pressure stability. Hence, linear finite elements can be used in the MPM solver. The main purpose of this new MPM formulation is to mitigate artificial pressure oscillations and time step restrictions present in the explicit MPM approach. First, a single phase MPM solver is applied to free surface incompressible fluid flow problems. Numerical results show a better approximation of the pressure field compared to the results obtained from the explicit MPM. The proposed formulation is then extended to model fully saturated porous materials with incompress- ible constituents. A solid velocity(v S )-fluid velocity (v F )-pore pressure (p) formulation is presented within the framework of mixture theory. Comparing the numerical results for the one-dimensional consolidation problem shows that the proposed incompressible MPM algorithm provides a stable and accurate pore pressure field even without implementing damping in the solver. Finally, the coupled MPM is used to solve a two-dimensional wave propagation problem and a plain strain consolidation problem. One of the important features of the proposed hydro mechanical coupled MPM formulation is that the time step size is not dependent on the incompressibility and the permeability of the porous medium.

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Wood, William Alfred. „Multi-dimensional Upwind Fluctuation Splitting Scheme with Mesh Adaption for Hypersonic Viscous Flow“. Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/29772.

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A multi-dimensional upwind fluctuation splitting scheme is developed and implemented for two-dimensional and axisymmetric formulations of the Navier-Stokes equations on unstructured meshes. Key features of the scheme are the compact stencil, full upwinding, and non-linear discretization which allow for second-order accuracy with enforced positivity. Throughout, the fluctuation splitting scheme is compared to a current state-of-the-art finite volume approach, a second-order, dual mesh upwind flux difference splitting scheme (DMFDSFV), and is shown to produce more accurate results using fewer computer resources for a wide range of test cases. The scalar test cases include advected shear, circular advection, non-linear advection with coalescing shock and expansion fans, and advection-diffusion. For all scalar cases the fluctuation splitting scheme is more accurate, and the primary mechanism for the improved fluctuation splitting performance is shown to be the reduced production of artificial dissipation relative to DMFDSFV. The most significant scalar result is for combined advection-diffusion, where the present fluctuation splitting scheme is able to resolve the physical dissipation from the artificial dissipation on a much coarser mesh than DMFDSFV is able to, allowing order-of-magnitude reductions in solution time. Among the inviscid test cases the converging supersonic streams problem is notable in that the fluctuation splitting scheme exhibits superconvergent third-order spatial accuracy. For the inviscid cases of a supersonic diamond airfoil, supersonic slender cone, and incompressible circular bump the fluctuation splitting drag coefficient errors are typically half the DMFDSFV drag errors. However, for the incompressible inviscid sphere the fluctuation splitting drag error is larger than for DMFDSFV. A Blasius flat plate viscous validation case reveals a more accurate vertical-velocity profile for fluctuation splitting, and the reduced artificial dissipation production is shown relative to DMFDSFV. Remarkably the fluctuation splitting scheme shows grid converged skin friction coefficients with only five points in the boundary layer for this case. A viscous Mach 17.6 (perfect gas) cylinder case demonstrates solution monotonicity and heat transfer capability with the fluctuation splitting scheme. While fluctuation splitting is recommended over DMFDSFV, the difference in performance between the schemes is not so great as to obsolete DMFDSFV. The second half of the dissertation develops a local, compact, anisotropic unstructured mesh adaption scheme in conjunction with the multi-dimensional upwind solver, exhibiting a characteristic alignment behavior for scalar problems. This alignment behavior stands in contrast to the curvature clustering nature of the local, anisotropic unstructured adaption strategy based upon a posteriori error estimation that is used for comparison. The characteristic alignment is most pronounced for linear advection, with reduced improvement seen for the more complex non-linear advection and advection-diffusion cases. The adaption strategy is extended to the two-dimensional and axisymmetric Navier-Stokes equations of motion through the concept of fluctuation minimization. The system test case for the adaption strategy is a sting mounted capsule at Mach-10 wind tunnel conditions, considered in both two-dimensional and axisymmetric configurations. For this complex flowfield the adaption results are disappointing since feature alignment does not emerge from the local operations. Aggressive adaption is shown to result in a loss of robustness for the solver, particularly in the bow shock/stagnation point interaction region. Reducing the adaption strength maintains solution robustness but fails to produce significant improvement in the surface heat transfer predictions.
Ph. D.

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Ravikumar, Devaki. „2D Compressible Viscous Flow Computations Using Acoustic Flux Vector Splitting (AFVS) Scheme“. Thesis, Indian Institute of Science, 2001. https://etd.iisc.ac.in/handle/2005/277.

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The present work deals with the extension of Acoustic Flux Vector Splitting (AFVS) scheme for the Compressible Viscous flow computations. Accurate viscous flow computations require much finer grids with adequate clustering of grid points in certain regions. Viscous flow computations are performed on unstructured triangulated grids. Solving Navier-Stokes equations involves the inviscid Euler part and the viscous part. The inviscid part of the fluxes are computed using the Acoustic Flux Vector Splitting scheme and the viscous part which is diffusive in nature does not require upwinding and is taken care using a central difference type of scheme. For these computations both the cell centered and the cell vertex finite volume methods are used. Higher order accuracy on unstructured meshes is achieved using the reconstruction procedure. Test cases are chosen in such a way that the performance of the scheme can be evaluated for different range of mach numbers. We demonstrate that higher order AFVS scheme in conjunction with a suitable grid adaptation strategy produce results that compare well with other well known schemes and the experimental data. An assessment of the relative performance of the AFVS scheme with the Roe scheme is also presented.

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Ravikumar, Devaki. „2D Compressible Viscous Flow Computations Using Acoustic Flux Vector Splitting (AFVS) Scheme“. Thesis, Indian Institute of Science, 2001. http://hdl.handle.net/2005/277.

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Laborde, Maxime. „Systèmes de particules en interaction, approche par flot de gradient dans l'espace de Wasserstein“. Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLED014/document.

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Depuis l’article fondateur de Jordan, Kinderlehrer et Otto en 1998, il est bien connu qu’une large classe d’équations paraboliques peuvent être vues comme des flots de gradient dans l’espace de Wasserstein. Le but de cette thèse est d’étendre cette théorie à certaines équations et systèmes qui n’ont pas exactement une structure de flot de gradient. Les interactions étudiées sont de différentes natures. Le premier chapitre traite des systèmes avec des interactions non locales dans la dérive. Nous étudions ensuite des systèmes de diffusions croisées s’appliquant aux modèles de congestion pour plusieurs populations. Un autre modèle étudié est celui où le couplage se trouve dans le terme de réaction comme les systèmes proie-prédateur avec diffusion ou encore les modèles de croissance tumorale. Nous étudierons enfin des systèmes de type nouveau où l’interaction est donnée par un problème de transport multi-marges. Une grande partie de ces problèmes est illustrée de simulations numériques
Since 1998 and the seminal work of Jordan, Kinderlehrer and Otto, it is well known that a large class of parabolic equations can be seen as gradient flows in the Wasserstein space. This thesis is devoted to extensions of this theory to equations and systems which do not have exactly a gradient flow structure. We study different kind of couplings. First, we treat the case of nonlocal interactions in the drift. Then, we study cross diffusion systems which model congestion for several species. We are also interested in reaction-diffusion systems as diffusive prey-predator systems or tumor growth models. Finally, we introduce a new class of systems where the interaction is given by a multi-marginal transport problem. In many cases, we give numerical simulations to illustrate our theorical results

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Stauffert, Maxime. „Simulation numérique d'écoulements compressibles complexes par des méthodes de type Lagrange-projection : applications aux équations de Saint-Venant“. Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLV045/document.

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On étudie dans le cadre de la thèse une famille de schémas numériques permettant de résoudre les équations de Saint-Venant. Ces schémas utilisent une décomposition d'opérateur de type Lagrange-projection afin de séparer les ondes de gravité et les ondes de transport. Un traitement implicite du système acoustique (relié aux ondes de gravité) permet aux schémas de rester stable avec de grands pas de temps. La correction des flux de pression rend possible l'obtention d'une solution approchée précise quel que soit le régime d'écoulement vis-à-vis du nombre de Froude. Une attention toute particulière est portée sur le traitement du terme source qui permet la prise en compte de l'influence de la topographie. On obtient notamment la propriété dite équilibre permettant de conserver exactement certains états stationnaires, appelés état du "lac au repos". Des versions 1D et 2D sur maillages non-structurés de ces méthodes ont été étudiées et implémentées dans un cadre volumes finis. Enfin, une extension vers des méthodes ordres élevés Galerkin discontinue a été proposée en 1D avec des limiteurs classiques ainsi que combinée avec une boucle MOOD de limitation a posteriori
In this thesis we study a family of numerical schemes solving the shallow water equations system. These schemes use a Lagrange-projection like splitting operator technique in order to separate the gravity waves and the transport waves. An implicit-explicit treatment of the acoustic system (linked to the gravity waves) allows the schemes to stay stable with large time step. The correction of the pressure fluxes enables the obtain of a precise approximation solution whatever the regime flow is with respect to the Froude number. A particular attention has been paid over the source term treatment which permits to take the topography into account. We especially obtain the so-called well-balanced property giving the exact conservation of some steady states, namely the "lake at rest" state. 1D and 2D versions of this methods have been studied and implemented in the finite volumes framework. Finally, a high order discontinuous Galerkin extension has been proposed in 1D with classical limiters along with a combined MOOD loop a posteriori limiting strategy

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Bücher zum Thema "Schéma de Splitting"

Meng-Sing, Liou, und United States. National Aeronautics and Space Administration., Hrsg. A flux splitting scheme with high-resolution and robustness for discontinuities. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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Dochan, Kwak, und Ames Research Center, Hrsg. An upwind-differencing scheme for the incompressible Navier-Stokes equations. Moffett Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 1988.

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A new flux splitting scheme. [Washington, DC]: National Aeronautics and Space Administration, 1991.

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An upwind-differencing scheme for the incompressible Navier-Stokes equations. Moffett Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 1988.

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Application of a third order upwind scheme to viscous flow over clean and iced wings: 32nd Aerospace Sciences Meeting & Exhibit, January 10-13, 1994/Reno, NV. Washington, D.C: American Institute of Aeronautics and Astronautics, 1994.

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Buchteile zum Thema "Schéma de Splitting"

Kolesov, Alexandr E., Petr N. Vabishchevich, Maria V. Vasilyeva und Victor F. Gornov. „Splitting Scheme for Poroelasticity and Thermoelasticity Problems“. In Finite Difference Methods,Theory and Applications, 241–48. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-20239-6_25.

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Martin, David James. „Novel Z-Scheme Overall Water Splitting Systems“. In Springer Theses, 123–43. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-18488-3_5.

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Bonfiglioli, A., P. De Palma, G. Pascazio und M. Napolitano. „An Implicit Fluctuation Splitting Scheme for Compressible Flows“. In Computational Fluid Dynamics 2000, 367–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56535-9_54.

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Boukili, Hamza, und Jean-Marc Hérard. „A Splitting Scheme for Three-Phase Flow Models“. In Springer Proceedings in Mathematics & Statistics, 109–17. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-57394-6_12.

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Beccantini, A. „Colella-Glaz Splitting Scheme for Thermally Perfect Gases“. In Godunov Methods, 89–95. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-0663-8_8.

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Yamamoto, Satoru, und Byeong Rog Shin. „Preconditioned Implicit Flux-splitting Scheme for Condensate Flows“. In Computational Fluid Dynamics 2002, 112–17. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-642-59334-5_13.

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Rossow, C. C. „A Simple Flux Splitting Scheme for Compressible Flows“. In Notes on Numerical Fluid Mechanics (NNFM), 355–62. Wiesbaden: Vieweg+Teubner Verlag, 1999. http://dx.doi.org/10.1007/978-3-663-10901-3_46.

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Barash, Danny, Moshe Israeli und Ron Kimmel. „An Accurate Operator Splitting Scheme for Nonlinear Difusion Filtering“. In Scale-Space and Morphology in Computer Vision, 281–89. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/3-540-47778-0_25.

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Friedman, Avner. „A pseudo non-time-splitting scheme in air quality modeling“. In Mathematics in Industrial Problems, 89–93. New York, NY: Springer New York, 1997. http://dx.doi.org/10.1007/978-1-4612-1858-6_10.

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Liu, Zhi-feng, Wen-hua Dou und Ya-jie Liu. „AMBTS: A Scheme of Aggregated Multicast Based on Tree Splitting“. In Lecture Notes in Computer Science, 829–40. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-24693-0_68.

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Konferenzberichte zum Thema "Schéma de Splitting"

Garrido, David, Hashem Moradmand und Borja Peleato. „An Online Coded Caching Scheme Without File Splitting“. In 2024 IEEE International Mediterranean Conference on Communications and Networking (MeditCom), 137–42. IEEE, 2024. http://dx.doi.org/10.1109/meditcom61057.2024.10621136.

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Ragonis, Eldar, Eran Ben-Arosh, Lev Merensky und Avner Fleischer. „Controlling High Harmonic Supercontinuum Generation with the Spectral Polarization of the Driver“. In CLEO: Fundamental Science, FM3B.5. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/cleo_fs.2024.fm3b.5.

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A High-Harmonic-Generation (HHG) scheme offering continuous control over the bandwidth of the spectral peaks is presented. The scheme uses a vectorial two-color driver with close frequencies, generated by spectrally splitting an input laser pulse and recombining the two halves after their polarizations are made cross-elliptical counter-rotating.

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Sawada, Keisuke. „A flux difference multidimensional splitting scheme“. In 14th Computational Fluid Dynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1999. http://dx.doi.org/10.2514/6.1999-3345.

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Rawal, Bharat S., und Yong Wang. „Splitting a PRE-scheme on Private Blockchain“. In 2019 IEEE Canadian Conference of Electrical and Computer Engineering (CCECE). IEEE, 2019. http://dx.doi.org/10.1109/ccece.2019.8861591.

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JHA, AKHILESH KUMAR, JUICHIRO AKIYAMA und MASARU URA. „FLUX-DIFFERENCE SPLITTING SCHEME FOR GRAVITY CURRENTS“. In Proceedings of the 8th International Symposium on Flow Modeling and Turbulence Measurements. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812777591_0034.

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Lin, Wei, Yi Tang und Bin Liu. „Traffic Splitting over ECMPs using ACC Scheme“. In 2006 First International Conference on Communications and Networking in China. IEEE, 2006. http://dx.doi.org/10.1109/chinacom.2006.344703.

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Tiselj, Iztok, und Andrej Horvat. „Accuracy of the Operator Splitting Technique for Two-Phase Flow With Stiff Source Terms“. In ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31349.

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Code for analysis of the water hammer in thermal-hydraulic systems is being developed within the WAHALoads project founded by the European Commission [1]. Code will be specialized for the simulations of the two-phase water hammer phenomena with the two-fluid model of two-phase flow. The proposed numerical scheme is a two-step second-order accurate scheme with operator splitting; i.e. convection and sources are treated separately. Operator splitting technique is a very simple and “easy-to-use” tool, however, when the source terms are stiff, operator splitting method becomes a source of a specific non-accuracy, which behaves as a numerical diffusion. This type of error is analyzed in the present paper.

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Zhou, Yue, Qiangming Zhou, Hongqiao Yu, Qian Pu, Yifan Zhou, Wei Hu und Yujiao Chen. „Splitting control decision scheme design and splitting control analysis in a provincial power grid“. In 2016 12th World Congress on Intelligent Control and Automation (WCICA). IEEE, 2016. http://dx.doi.org/10.1109/wcica.2016.7578263.

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Yan, Zhiwei, Anlei Hu und Wei Wang. „A cache-splitting scheme for DNS recursive server“. In 2012 IEEE 2nd International Conference on Cloud Computing and Intelligence Systems (CCIS). IEEE, 2012. http://dx.doi.org/10.1109/ccis.2012.6664588.

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Dorodnyy, Alexander, Valery Shklover, Leonid Braginsky, Christian Hafner und Juerg Leuthold. „Spectrum splitting double-cell scheme for solar photovoltaics“. In 2014 IEEE 40th Photovoltaic Specialists Conference (PVSC). IEEE, 2014. http://dx.doi.org/10.1109/pvsc.2014.6925365.

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Berichte der Organisationen zum Thema "Schéma de Splitting"

Li, Yongjun. NSLS-II upgrade proposal with splitting dipole scheme. Office of Scientific and Technical Information (OSTI), September 2018. http://dx.doi.org/10.2172/1504400.

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