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Letteratura scientifica selezionata sul tema "Lattice Boltzmann scheme"

Autore: Grafiati

Pubblicato: 16 settembre 2023

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Articoli di riviste sul tema "Lattice Boltzmann scheme"

1

Dubois, François, e Pierre Lallemand. "On Triangular Lattice Boltzmann Schemes for Scalar Problems". Communications in Computational Physics 13, n. 3 (marzo 2013): 649–70. http://dx.doi.org/10.4208/cicp.381011.270112s.

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AbstractWe propose to extend the d’Humieres version of the lattice Boltzmann scheme to triangular meshes. We use Bravais lattices or more general lattices with the property that the degree of each internal vertex is supposed to be constant. On such meshes, it is possible to define the lattice Boltzmann scheme as a discrete particle method, without need of finite volume formulation or Delaunay-Voronoi hypothesis for the lattice. We test this idea for the heat equation and perform an asymptotic analysis with the Taylor expansion method for two schemes named D2T4 and D2T7. The results show a convergence up to second order accuracy and set new questions concerning a possible super-convergence.

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2

Venturi, Sara, Silvia Di Francesco, Martin Geier e Piergiorgio Manciola. "Forcing for a Cascaded Lattice Boltzmann Shallow Water Model". Water 12, n. 2 (6 febbraio 2020): 439. http://dx.doi.org/10.3390/w12020439.

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This work compares three forcing schemes for a recently introduced cascaded lattice Boltzmann shallow water model: a basic scheme, a second-order scheme, and a centred scheme. Although the force is applied in the streaming step of the lattice Boltzmann model, the acceleration is also considered in the transformation to central moments. The model performance is tested for one and two dimensional benchmarks.

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3

Xu, Kun, e Li-Shi Luo. "Connection Between Lattice-Boltzmann Equation and Beam Scheme". International Journal of Modern Physics C 09, n. 08 (dicembre 1998): 1177–87. http://dx.doi.org/10.1142/s0129183198001072.

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In this paper we analyze and compare the lattice-Boltzmann equation with the beam scheme in detail. We notice the similarity and differences between the lattice Boltzmann equation and the beam scheme. We show that the accuracy of the lattice-Boltzmann equation is indeed second order in space. We discuss the advantages and limitations of the lattice-Boltzmann equation and the beam scheme. Based on our analysis, we propose an improved multi-dimensional beam scheme.

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4

Gao, Shangwen, Chengbin Zhang, Yingjuan Zhang, Qiang Chen, Bo Li e Suchen Wu. "Revisiting a class of modified pseudopotential lattice Boltzmann models for single-component multiphase flows". Physics of Fluids 34, n. 5 (maggio 2022): 057103. http://dx.doi.org/10.1063/5.0088246.

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Since its emergence, the pseudopotential lattice Boltzmann (LB) method has been regarded as a straightforward and practical approach for simulating single-component multiphase flows. However, its original form always results in a thermodynamic inconsistency, which, thus, impedes its further application. Several strategies for modifying the force term have been proposed to eliminate this limitation. In this study, four typical and widely used improved schemes—Li's single-relaxation-time (SRT) scheme [Li et al., “Forcing scheme in pseudopotential lattice Boltzmann model for multiphase flows,” Phys. Rev. E 86, 016709 (2012)] and multiple-relaxation-times (MRT) scheme [Li et al., “Lattice Boltzmann modeling of multiphase flows at large density ratio with an improved pseudopotential model,” Phys. Rev. E 87, 053301 (2013)], Kupershtokh's SRT scheme [Kupershtokh et al., “On equations of state in a lattice Boltzmann method,” Comput. Math. Appl. 58, 965 (2009)], and Huang's MRT scheme [Huang and Wu, “Third-order analysis of pseudopotential lattice Boltzmann model for multiphase flow,” J. Comput. Phys. 327, 121 (2016)]—are systematically analyzed and intuitively compared after an extension of the MRT framework. The theoretical and numerical results both indicate that the former three schemes are specific forms of the last one, which thus help further understand the improvements of these pseudopotential LB models for achieving thermodynamic consistency. In addition, we modified the calculation of the additional source term in the LB evolution equation. Numerical results for stationary and moving droplets confirm the higher accuracy.

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5

van der Sman, R. G. M., e M. H. Ernst. "Convection-Diffusion Lattice Boltzmann Scheme for Irregular Lattices". Journal of Computational Physics 160, n. 2 (maggio 2000): 766–82. http://dx.doi.org/10.1006/jcph.2000.6491.

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6

Qiu, Ruofan, Rongqian Chen e Yancheng You. "An implicit-explicit finite-difference lattice Boltzmann subgrid method on nonuniform meshes". International Journal of Modern Physics C 28, n. 04 (aprile 2017): 1750045. http://dx.doi.org/10.1142/s0129183117500450.

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In this paper, an implicit-explicit finite-difference lattice Boltzmann method with subgrid model on nonuniform meshes is proposed. The implicit-explicit Runge–Kutta scheme, which has good convergence rate, is used for the time discretization and a mixed difference scheme, which combines the upwind scheme with the central scheme, is adopted for the space discretization. Meanwhile, the standard Smagorinsky subgrid model is incorporated into the finite-difference lattice Boltzmann scheme. The effects of implicit-explicit Runge–Kutta scheme and nonuniform meshes of present lattice Boltzmann method are discussed through simulations of a two-dimensional lid-driven cavity flow on nonuniform meshes. Moreover, the comparison simulations of the present method and multiple relaxation time lattice Boltzmann subgrid method are conducted qualitatively and quantitatively.

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7

Wen, Mengke, Weidong Li e Zhangyan Zhao. "A hybrid scheme coupling lattice Boltzmann method and finite-volume lattice Boltzmann method for steady incompressible flows". Physics of Fluids 34, n. 3 (marzo 2022): 037114. http://dx.doi.org/10.1063/5.0085370.

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We present a new hybrid method coupling the adaptive mesh refinement lattice Boltzmann method (AMRLBM) and the finite-volume lattice Boltzmann method (FVLBM) to improve both the simulation efficiency and adaptivity for steady incompressible flows with complex geometries. The present method makes use of the domain decomposition, in which the FVLBM sub-domain is applied to the region adjacent to the walls, and is coupled to the lattice Boltzmann method (LBM) sub-domain in the rest of the flow field to enhance the ability of the LBM to deal with irregular geometries without sacrificing the high efficiency and accuracy property of the LBM. In the LBM sub-domain, a cell-centered lattice structure-based AMRLBM is used and, in the FVLBM sub-domain, the gas-kinetic Bhatnagar–Gross–Krook (BGK) scheme-based FVLBM is adopted to reduce the numerical dissipation and enhance the efficiency of FVLBM. Moreover, not like the conventional LBM and Navier–Stokes equation solver-based hybrid schemes, the present hybrid scheme combines two kinds of lattice Boltzmann equation solvers, that is, AMRLBM and FVLBM, which makes the present scheme much simpler and better consistency than the conventional hybrid schemes. To assess the accuracy and efficacy of the proposed method, various benchmark studies, including the Kovasznay flow, the lid-driven cavity flow with Reynolds number [Formula: see text], 400, and 1000, and the steady flow past a cylinder with [Formula: see text] and 40, are also conducted. The numerical results show that the present scheme can be an efficient and reliable method for steady incompressible flows.

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8

LALLEMAND, PIERRE, e LI-SHI LUO. "HYBRID FINITE-DIFFERENCE THERMAL LATTICE BOLTZMANN EQUATION". International Journal of Modern Physics B 17, n. 01n02 (20 gennaio 2003): 41–47. http://dx.doi.org/10.1142/s0217979203017060.

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We analyze the acoustic and thermal properties of athermal and thermal lattice Boltzmann equation (LBE) in 2D and show that the numerical instability in the thermal lattice Boltzmann equation (TLBE) is related to the algebraic coupling among different modes of the linearized evolution operator. We propose a hybrid finite-difference (FD) thermal lattice Boltzmann equation (TLBE). The hybrid FD-TLBE scheme is far superior over the existing thermal LBE schemes in terms of numerical stability. We point out that the lattice BGK equation is incompatible with the multiple relaxation time model.

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Wang, Liang, Zhaoli Guo, Baochang Shi e Chuguang Zheng. "Evaluation of Three Lattice Boltzmann Models for Particulate Flows". Communications in Computational Physics 13, n. 4 (aprile 2013): 1151–72. http://dx.doi.org/10.4208/cicp.160911.200412a.

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AbstractA comparative study is conducted to evaluate three types of lattice Boltzmann equation (LBE) models for fluid flows with finite-sized particles, including the lattice Bhatnagar-Gross-Krook (BGK) model, the model proposed by Ladd [Ladd AJC, J. Fluid Mech., 271, 285-310 (1994); Ladd AJC, J. Fluid Mech., 271, 311-339 (1994)], and the multiple-relaxation-time (MRT) model. The sedimentation of a circular particle in a two-dimensional infinite channel under gravity is used as the first test problem. The numerical results of the three LBE schemes are compared with the theoretical results and existing data. It is found that all of the three LBE schemes yield reasonable results in general, although the BGK scheme and Ladd’s scheme give some deviations in some cases. Our results also show that the MRT scheme can achieve a better numerical stability than the other two schemes. Regarding the computational efficiency, it is found that the BGK scheme is the most superior one, while the other two schemes are nearly identical. We also observe that the MRT scheme can unequivocally reduce the viscosity dependence of the wall correction factor in the simulations, which reveals the superior robustness of the MRT scheme. The superiority of the MRT scheme over the other two schemes is also confirmed by the simulation of the sedimentation of an elliptical particle.

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Van Der Sman, R. G. M. "Lattice-Boltzmann Scheme for Natural Convection in Porous Media". International Journal of Modern Physics C 08, n. 04 (agosto 1997): 879–88. http://dx.doi.org/10.1142/s0129183197000758.

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A lattice-Boltzmann scheme for natural convection in porous media is developed and applied to the heat transfer problem of a 1000 kg potato packaging. The scheme has features new to the field of LB schemes. It is mapped on a orthorhombic lattice instead of the traditional cubic lattice. Furthermore the boundary conditions are formulated with a single paradigm based upon the particle fluxes. Our scheme is well able to reproduce (1) the analytical solutions of simple model problems and (2) the results from cooling down experiments with potato packagings.

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Più fonti

Tesi sul tema "Lattice Boltzmann scheme"

1

Karra, Satish. "Modeling electrospinning process and a numerical scheme using Lattice Boltzmann method to simulate viscoelastic fluid flows". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1347.

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2

Späth, Peter. "Renewed Theory, Interfacing, and Visualization of Thermal Lattice Boltzmann Schemes". Doctoral thesis, Universitätsbibliothek Chemnitz, 2000. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200000648.

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In this Doktorarbeit the Lattice Boltzmann scheme, a heuristic method for the simulation of flows in complicated boundaries, is investigated. Its theory is renewed by emphasizing the entropy maximization principle, and new means for the modelling of geometries (including moving boundaries) and the visual representation of evoluting flows are presented. An object oriented implemen- tation is given with communication between objects realized by an interpreter object and communication from outside realized via interprocess communica- tion. Within the new theoretical apprach the applicability of existing Lattice Boltzmann schemes to model thermal flows for arbitrary temperatures is reex- amined
In dieser Doktorarbeit wird das Gitter-Boltzmann-Schema, eine heuristische Methode fuer die Simulation von Stroemungen innerhalb komplexer Raender, untersucht. Die zugrundeliegende Theorie wird unter neuen Gesichtspunkten, insbesondere dem Prinzip der Entropiemaximierung, betrachtet. Des weiteren werden neuartige Methoden fuer die Modellierung der Geometrie (einschl. beweglicher Raender) und der visuellen Darstellung aufgezeigt. Eine objektorientierte Implementierung wird vorgestellt, wobei die Kommunikation zwischen den Objekten über Interpreter-Objekte und die Kommunikation mit der Aussenwelt ueber Interprozess-Kommunikation gehandhabt wird. Mit dem neuen theoretischen Ansatz wird die Gueltigkeit bestehender Gitter-Boltzmann-Schemata fuer die Anwendung auf Stroemungen mit nicht konstanter Temperatur untersucht

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3

Michelet, Jordan. "Extraction du fouillis de mer dans des images radar marin cohérent : modèles de champ de phases, méthodes de Boltzmann sur réseau, apprentissage". Electronic Thesis or Diss., La Rochelle, 2022. http://www.theses.fr/2022LAROS048.

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Nous nous intéressons au problème d’extraction du fouillis de mer dans des images radar marin. Le parti pris est de développer des méthodes de traitement d’image permettant de s’affranchir au mieux d’hypothèses sur la nature du fouillis de mer et du signal d’intérêt. D’une part, nous proposons un algorithme basé sur une approche variationnelle originale : un modèle multiphasique à interface diffuse. Les résultats obtenus montrent que l’algorithme est efficace lorsque le signal d’intérêt a un rapport signal-sur-fouillis suffisamment grand. D’autre part, nous nous intéressons à l’implémentation de schémas de Boltzmann sur réseau pour des problèmes de convection-diffusion à vitesse d’advection non constante et un terme source non nul. Nous décrivons le calcul de la consistance obtenue par analyse asymptotique à l’échelle acoustique et avec un opérateur de collision à temps de relaxation multiples, et étudions la stabilité de ces schémas dans un cas particulier. Les résultats obtenus montrent que les schémas proposés permettent de supprimer le bruit résiduel et de renforcer le signal d’intérêt sur l’image obtenue grâce à la première méthode. Enfin, nous proposons une méthode d’apprentissage permettant de s’affranchir d’hypothèses sur la nature du signal d’intérêt. En effet, en complément de l’algorithme par approche variationnelle, nous proposons un algorithme basé sur le traitement pulse-Doppler lorsque le signal d’intérêt est exo-clutter et a un rapport signal-sur-fouillis faible. Les résultats obtenus à partir du double auto-encodeur que nous proposons, étant comparables aux résultats fournis par chacune des deux méthodes, permettent de valider cette approche
We focus on the problem of sea clutter extraction in marine radar images. The aim is to develop image processing methods allowing us to avoid assumptions about the nature of the sea clutter and the signal of interest. On the one hand, we propose an original algorithm based on a variational approach : a multiphase model with diffuse interface. The results obtained show that the algorithm is efficient when the signal of interest has a sufficiently large signal-to-clutter ratio. On the other hand, we focus on the implementation of lattice Boltzmann schemes for convection-diffusion problems with non-constant advection velocity and non-zero source term. We describe the computation of the consistency obtained by asymptotic analysis at the acoustic scale and with a multiple relaxation time collision operator, and study the stability of these schemes in a particular case. The obtained results show that the proposed schemes allow removing the residual noise and to enhance the signal of interest on the image obtained with the first method. Finally, we propose a learning method allowing us to avoid assumptions on the nature of the signal of interest. Indeed, in addition to the variational approach, we propose an algorithm based on pulse-Doppler processing when the signal of interest is exo-clutter and has a low signal-to-clutter ratio. The results obtained from the proposed double auto-encoder, being comparable to the results provided by each of the two methods, allow validating this approach

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4

Uphoff, Sonja [Verfasser], e Manfred [Akademischer Betreuer] Krafczyk. "Development and Validation of turbulence models for Lattice Boltzmann schemes / Sonja Uphoff ; Betreuer: Manfred Krafczyk". Braunschweig : Technische Universität Braunschweig, 2013. http://d-nb.info/1175821896/34.

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5

Février, Tony. "Extension et analyse des schémas de Boltzmann sur réseau : les schémas à vitesse relative". Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112316/document.

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Cette thèse introduit et étudie une nouvelle classe de schémas de Boltzmann sur réseau appelés schémas à vitesse relative. Les schémas de Boltzmann sur réseau visent à approcher des problèmes de nature macroscopique en mimant la dynamique microscopique d’équations cinétiques du type Boltzmann. L’algorithme calcule des distributions de particules évoluant au travers de deux phases de transport et de relaxation, les particules se déplaçant en les noeuds d’un réseau cartésien en espace. Les schémas de Boltzmann à plusieurs temps de relaxation (ou schéma MRT de d’Humières), dont la relaxation im- plique un ensemble de moments combinaison linéaire polynomiale des distributions, constituent le cadre initial de la thèse. Les schémas à vitesse relative sont une extension de ces schémas de d’Humières. Ils sont inspirés du schéma cascade de Geier apportant davantage de stabilité que les schémas de d’Hu- mières pour des régimes peu visqueux des équations de Navier-Stokes. La différence avec ces schémas se situe au niveau de la relaxation : elle utilise un ensemble de moments relatifs à un paramètre champ de vitesse fonction du temps et de l’espace. Cette différence se matérialise par une matrice de tran- sition des moments fixes (les schémas de d’Humières correspondent à un paramètre champ de vitesse nul) aux moments mobiles. La structure algébrique de cette matrice est étudiée. Le schéma cascade est ensuite traduit comme un schéma à vitesse relative pour un nouvel ensemble de polynômes définissant les moments. L’étude de la consistance des schémas à vitesse relative par la méthode des équations équivalentes est un point central de la thèse. Les équations limites pour un nombre arbitraire de dimen- sions et de vitesses sont dérivées et illustrées sur des exemples tels que le D2Q9 pour les équations de Navier-Stokes. Ces équations équivalentes sont également un outil pour prédire la stabilité des schémas grâce à l’analyse des termes de diffusion et dispersion. La dernière partie traite de la stabilité suivant le choix du paramètre champ de vitesse. Nous sommes particulièrement intéressés en les deux choix de paramètre nul (d’Humières) et la vitesse du fluide (cascade). Le schéma D2Q9 pour les équations de Navier-Stokes est étudié numériquement par une méthode de Von Neumann puis appuyé sur des cas tests non linéaires. La stabilité des schémas relatifs à la vitesse du fluide est dépendante du choix des polynômes définissant les moments. L’amélioration la plus notable se produit si les polynômes du schéma cascade sont choisis. Nous étudions enfin les stabilités théorique et numérique d’un schéma bidimensionnel minimal. Le contexte physique est la simulation d’une équation d’advection diffusion linéaire. Le choix de la vitesse d’advection comme paramètre champ de vitesse annule certains termes de dispersion des équations équivalentes contrairement aux schémas de d’Humières. Ceci se traduit par un meilleur comportement en termes de stabilité pour de grandes vitesses, appuyé théoriquement à l’aide d’une notion de stabilité à poids
In this PhD thesis, a new class of lattice Boltzmann schemes called relative velocity schemes is introduced and studied. The purpose of lattice Boltzmann schemes is to approximate problems of macroscopic nature using the microscopic dynamic of Boltzmann type kinetic equations. They compute particle distributions through two phases of transport and relaxation, the particles moving on the nodes of a cartesian lattice. The multiple relaxation times schemes---MRT of d'Humières---, whose relaxation uses a set of moments, linear combinations of the particle distributions, constitutes the initial framework of the thesis. The relative velocity schemes extend the MRT d'Humières schemes. They originate from the cascaded automaton of Geier which provides more stability for the low viscosity regime of the Navier-Stokes equations. Their difference with the d'Humières schemes is carried by the relaxation : a set of moments relative to a velocity field parameter function of space and time is used. This difference is represented by a shifting matrix sending the fixed moments---The d'Humières schemes are associated with a zero velocity field parameter---On the relative moments. The algebraic structure of this matrix is studied. The cascaded automaton is then interpreted as a relative velocity scheme for a new set of polynomials defining the moments. The consistency study of the relative velocity schemes with the equivalent equations method is a keypoint of the thesis. These equations are derived for an arbitrary number of dimensions and velocities. They are then illustrated on examples like the D2Q9 scheme for the Navier-Stokes equations. These equivalent equations are also a tool to predict the stability behaviour of the schemes by analysing their diffusion and dispersion terms. In a last part, the stability according to the velocity field parameter is studied. Two cases especially interest us : a parameter equal to zero---D'Humières schemes---And equal to the fluid velocity---Cascaded automaton. The D2Q9 scheme for the Navier-Stokes equations is numerically studied with a linear Von Neumann analysis and some non linear test cases. The stability of the relative velocity schemes depends on the choice of the polynomials defining the moments. The most important improvement occurs if the polynomials of the cascaded automaton are chosen. We finally study the theoretical and numerical stability of a minimal bidimensional scheme for a linear advection diffusion equation. If the velocity field parameter is chosen equal to the advection velocity, some dispersion terms of the equivalent equations vanish unlike the d'Humières scheme. This implies a better stability behaviour for high velocities, characterized thanks to theoretical weighted stability notion

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6

Jobic, Yann. "Numerical approach by kinetic methods of transport phenomena in heterogeneous media". Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4723/document.

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Les phénomènes de transport en milieux poreux sont étudiés depuis près de deux siècles, cependant les travaux concernant les milieux fortement poreux sont encore relativement peu nombreux. Les modèles couramment utilisés pour les poreux classiques (lits de grains par exemple) sont peu applicables pour les milieux fortement poreux (les mousses par exemple), un certain nombre d’études ont été entreprises pour combler ce manque. Néanmoins, les résultats expérimentaux et numériques caractérisant les pertes de charge dans les mousses sont fortement dispersés. Du fait des progrès de l’imagerie 3D, une tendance émergente est la détermination des paramètres des lois d’écoulement à partir de simulations directes sur des géométries reconstruites. Nous présentons ici l’utilisation d’une nouvelle approche cinétique pour résoudre localement les équations de Navier-Stokes et déterminer les propriétés d’écoulement (perméabilité, dispersion, ...)
A novel kinetic scheme satisfying an entropy condition is developed, tested and implemented for the simulation of practical problems. The construction of this new entropic scheme is presented. A classical hyperbolic system is approximated by a discrete velocity vector kinetic scheme (with the simplified BGK collisional operator), but applied to an inviscid compressible gas dynamics system with a small Mach number parameter, according to the approach of Carfora and Natalini (2008). The numerical viscosity is controlled, and tends to the physical viscosity of the Navier-Stokes system. The proposed numerical scheme is analyzed and formulated as an explicit finite volume flux vector splitting (FVS) scheme that is very easy to implement. It is close in spirit to Lattice Boltzmann schemes, but it has the advantage to satisfy a discrete entropy inequality under a CFL condition and a subcharacteristic stability condition involving a cell Reynolds number. The new scheme is proved to be second-order accurate in space. We show the efficiency of the method in terms of accuracy and robustness on a variety of classical benchmark tests. Some physical problems have been studied in order to show the usefulness of both schemes. The LB code was successfully used to determine the longitudinal dispersion of metallic foams, with the use of a novel indicator. The entropic code was used to determine the permeability tensor of various porous media, from the Fontainebleau sandstone (low porosity) to a redwood tree sample (high porosity). These results are pretty accurate. Finally, the entropic framework is applied to the advection-diffusion equation as a passive scalar

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7

Kotnala, Sourabh. "Lattice Boltzmann Relaxation Scheme for Compressible Flows". Thesis, 2012. http://etd.iisc.ac.in/handle/2005/3257.

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Lattice Boltzmann Method has been quite successful for incompressible flows. Its extension for compressible (especially supersonic and hypersonic) flows has attracted lot of attention in recent time. There have been some successful attempts but nearly all of them have either resulted in complex or expensive equilibrium function distributions or in extra energy levels. Thus, an efficient Lattice Boltzmann Method for compressible fluid flows is still a research idea worth pursuing for. In this thesis, a new Lattice Boltzmann Method has been developed for compressible flows, by using the concept of a relaxation system, which is traditionally used as semilinear alternative for non-linear hypebolic systems in CFD. In the relaxation system originally introduced by Jin and Xin (1995), the non-linear flux in a hyperbolic conservation law is replaced by a new variable, together with a relaxation equation for this new variable augmented by a relaxation term in which it relaxes to the original nonlinear flux, in the limit of a vanishing relaxation parameter. The advantage is that instead of one non-linear hyperbolic equation, two linear hyperbolic equations need to be solved, together with a non-linear relaxation term. Based on the interpretation of Natalini (1998) of a relaxation system as a discrete velocity Boltzmann equation, with a new isotropic relaxation system as the basic building block, a Lattice Boltzmann Method is introduced for solving the equations of inviscid compressible flows. Since the associated equilibrium distribution functions of the relaxation system are not based on a low Mach number expansion, this method is not restricted to the incompressible limit. Free slip boundary condition is introduced with this new relaxation system based Lattice Boltzmann method framework. The same scheme is then extended for curved boundaries using the ghost cell method. This new Lattice Boltzmann Relaxation Scheme is successfully tested on various bench-mark test cases for solving the equations of compressible flows such as shock tube problem in 1-D and in 2-D the test cases involving supersonic flow over a forward-facing step, supersonic oblique shock reflection from a flat plate, supersonic and hypersonic flows past half-cylinder.

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8

Kotnala, Sourabh. "Lattice Boltzmann Relaxation Scheme for Compressible Flows". Thesis, 2012. http://hdl.handle.net/2005/3257.

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Abstract (sommario):

Lattice Boltzmann Method has been quite successful for incompressible flows. Its extension for compressible (especially supersonic and hypersonic) flows has attracted lot of attention in recent time. There have been some successful attempts but nearly all of them have either resulted in complex or expensive equilibrium function distributions or in extra energy levels. Thus, an efficient Lattice Boltzmann Method for compressible fluid flows is still a research idea worth pursuing for. In this thesis, a new Lattice Boltzmann Method has been developed for compressible flows, by using the concept of a relaxation system, which is traditionally used as semilinear alternative for non-linear hypebolic systems in CFD. In the relaxation system originally introduced by Jin and Xin (1995), the non-linear flux in a hyperbolic conservation law is replaced by a new variable, together with a relaxation equation for this new variable augmented by a relaxation term in which it relaxes to the original nonlinear flux, in the limit of a vanishing relaxation parameter. The advantage is that instead of one non-linear hyperbolic equation, two linear hyperbolic equations need to be solved, together with a non-linear relaxation term. Based on the interpretation of Natalini (1998) of a relaxation system as a discrete velocity Boltzmann equation, with a new isotropic relaxation system as the basic building block, a Lattice Boltzmann Method is introduced for solving the equations of inviscid compressible flows. Since the associated equilibrium distribution functions of the relaxation system are not based on a low Mach number expansion, this method is not restricted to the incompressible limit. Free slip boundary condition is introduced with this new relaxation system based Lattice Boltzmann method framework. The same scheme is then extended for curved boundaries using the ghost cell method. This new Lattice Boltzmann Relaxation Scheme is successfully tested on various bench-mark test cases for solving the equations of compressible flows such as shock tube problem in 1-D and in 2-D the test cases involving supersonic flow over a forward-facing step, supersonic oblique shock reflection from a flat plate, supersonic and hypersonic flows past half-cylinder.

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9

Chen, Su-Yuan, e 陳司原. "Development of Semiclassical Lattice Boltzmann Method Using Multi Relaxation Time Scheme for Flow Field Simulation". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/99784384360484233614.

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碩士
國立臺灣大學
應用力學研究所
100
A Multi Relaxation Time Semiclassical Lattice Boltzmann Method based on the Uehling-Uhlenbeck Boltzmann-BGK equation （Uehling-Uhlenbeck Boltzmann Bhatnagar-Gross-Krook Equation）and Multi Relaxation Time Lattice Boltzmann Method（MRT-LBM）is presented. The method is directly derived by projecting the kinetic governing equation onto the tensor Hermite polynomials and various hydrodynamic approximation orders can be achieved. Simulations of the lid　driven cavity flows based on D2Q9 lattice model for several Reynolds numbers and three different particles that obey Bose-Einstein and Fermi-Dirac and Maxwell-Boltzmann statistics are shown to illustrate the method. The results indicate distinct characteristics of the effects of quantum statistics.

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Kuriščák, Pavel. "Simulace proudění nenewtonovských tekutin pomocí lattice Boltzmannovy metody". Master's thesis, 2011. http://www.nusl.cz/ntk/nusl-313927.

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Title: Non-newtonian fluid flow simulation using lattice Boltzmann method Author: Bc. Pavel Kuriščák Department: Mathematical Institute, Charles University Supervisor: RNDr. Ing. Jaroslav Hron Ph.D. Supervisor's e-mail address: Jaroslav.Hron@mff.cuni.cz Abstract: The aim of this thesis is to find and estabilish a modification to the Lattice Boltzmann Method, allowing it to simulate non-newtonian behaviour of fluids. In the theoretical part of thesis, there is introduced a derivation, based on the work of [22], that is capable of arriving to macroscopical Navier-Stokes equa- tions completely a priori from the Boltzmann equation, utilizing the Hermite basis expansion. This derivation is afterwards applied to the method suggested by [11], that uses the changed equilibrium distribution to fine-tune the local fluid viscosity according to the non-newtonian model. In the last part of thesis, this method is implemented in the form of lattice kinetic scheme and tested on three sample problems. Keywords: Lattice Boltzmann Method, non-newtonian fluids, Hermite expansion, lattice kinetic scheme

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Libri sul tema "Lattice Boltzmann scheme"

1

Kun, Xu. Connection between the lattice Boltzmann equation and the beam scheme. Hampton, VA: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1999.

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Succi, Sauro. Lattice Boltzmann Models for Microflows. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199592357.003.0029.

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The Lattice Boltzmann method was originally devised as a computational alternative for the simulation of macroscopic flows, as described by the Navier–Stokes equations of continuum mechanics. In many respects, this still is the main place where it belongs today. Yet, in the past decade, LB has made proof of a largely unanticipated versatility across a broad spectrum of scales, from fully developed turbulence, to microfluidics, all the way down to nanoscale flows. Even though no systematic analogue of the Chapman–Enskog asymptotics is available in this beyond-hydro region (no guarantee), the fact remains that, with due extensions of the basic scheme, the LB has proven capable of providing several valuable insights into the physics of flows at micro- and nano-scales. This does not mean that LBE can solve the actual Boltzmann equation or replace Molecular Dynamics, but simply that it can provide useful insights into some flow problems which cannot be described within the realm of the Navier–Stokes equations of continuum mechanics. This Chapter provides a cursory view of this fast-growing front of modern LB research.

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Succi, Sauro. Entropic Lattice Boltzmann. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199592357.003.0021.

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The LB with enhanced collisions opened the way to the top-down design of LB schemes, with major gains in flexibility and computational efficiency. However, compliance with the second principle was swept under the carpet in the process, with detrimental effects on the numerical stability of the method. It is quite fortunate that, albeit forgotten, the above compliance did not get lost in the top-down procedure. Entropic LB schemes, the object of the present chapter, explain the whys and hows of this nice smile of Lady Luck.

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Succi, Sauro. Lattice Relaxation Schemes. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199592357.003.0014.

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In Chapter 13, it was shown that the complexity of the LBE collision operator can be cut down dramatically by formulating discrete versions with prescribed local equilibria. In this chapter, the process is taken one step further by presenting a minimal formulation whereby the collision matrix is reduced to the identity, upfronted by a single relaxation parameter, fixing the viscosity of the lattice fluid. The idea is patterned after the celebrated Bhatnagar–Gross–Krook (BGK) model Boltzmann introduced in continuum kinetic theory as early as 1954. The second part of the chapter describes the comeback of the early LBE in optimized multi-relaxation form, as well as few recent variants hereof.

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Cantor, Brian. The Equations of Materials. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198851875.001.0001.

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This book describes some of the important equations of materials and the scientists who derived them. It is aimed at anyone interested in the manufacture, structure, properties and engineering application of materials such as metals, polymers, ceramics, semiconductors and composites. It is meant to be readable and enjoyable, a primer rather than a textbook, covering only a limited number of topics and not trying to be comprehensive. It is pitched at the level of a final year school student or a first year undergraduate who has been studying the physical sciences and is thinking of specialising into materials science and/or materials engineering, but it should also appeal to many other scientists at other stages of their career. It requires a working knowledge of school maths, mainly algebra and simple calculus, but nothing more complex. It is dedicated to a number of propositions, as follows: 1. The most important equations are often simple and easily explained; 2. The most important equations are often experimental, confirmed time and again; 3. The most important equations have been derived by remarkable scientists who lived interesting lives. Each chapter covers a single equation and materials subject. Each chapter is structured in three sections: first, a description of the equation itself; second, a short biography of the scientist after whom it is named; and third, a discussion of some of the ramifications and applications of the equation. The biographical sections intertwine the personal and professional life of the scientist with contemporary political and scientific developments. The topics included are: Bravais lattices and crystals; Bragg’s law and diffraction; the Gibbs phase rule and phases; Boltzmann’s equation and thermodynamics; the Arrhenius equation and reactions; the Gibbs-Thomson equation and surfaces; Fick’s laws and diffusion; the Scheil equation and solidification; the Avrami equation and phase transformations; Hooke’s law and elasticity; the Burgers vector and plasticity; Griffith’s equation and fracture; and the Fermi level and electrical properties.

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Capitoli di libri sul tema "Lattice Boltzmann scheme"

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Vergassola, Massimo, R. Benzi e S. Succi. "A Lattice Boltzmann Scheme for the Burger Equation". In Correlations and Connectivity, 320–21. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2157-3_37.

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van der Sman, R. G. M. "Lattice Boltzmann Scheme for Diffusion on Triangular Grids". In Lecture Notes in Computer Science, 1072–81. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/3-540-44860-8_111.

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Albuquerque, Paul, Davide Alemani, Bastien Chopard e Pierre Leone. "Coupling a Lattice Boltzmann and a Finite Difference Scheme". In Computational Science - ICCS 2004, 540–47. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-25944-2_70.

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Derksen, J. J., J. L. Kooman e H. E. A. van den Akker. "Parallel fluid flow simulations by means of a lattice-Boltzmann scheme". In High-Performance Computing and Networking, 524–30. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/bfb0031625.

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Zhang, Tao, e Shuyu Sun. "A Compact and Efficient Lattice Boltzmann Scheme to Simulate Complex Thermal Fluid Flows". In Lecture Notes in Computer Science, 149–62. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-93713-7_12.

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Mohamad, A. A. "Multi-Relaxation Schemes". In Lattice Boltzmann Method, 101–5. London: Springer London, 2011. http://dx.doi.org/10.1007/978-0-85729-455-5_7.

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Mohamad, A. A. "Multi-Relaxation Schemes". In Lattice Boltzmann Method, 145–49. London: Springer London, 2019. http://dx.doi.org/10.1007/978-1-4471-7423-3_10.

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Dünweg, B., P. Ahlrichs e R. Everaers. "Simulation of the Dynamics of Polymers in Solution via a Hybrid Molecular Dynamics-Lattice Boltzmann Scheme". In Springer Proceedings in Physics, 260–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-642-59406-9_32.

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Banda, Mapundi Kondwani. "Variants of Relaxation Schemes and the Lattice Boltzmann Model Relaxation Systems". In Numerical Mathematics and Advanced Applications, 89–101. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-642-18775-9_6.

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Saritha Reddy, Gaddam, e R. Banerjee. "Evaluation of Forcing Schemes in Pseudopotential Based Multiphase Lattice Boltzmann Model". In Fluid Mechanics and Fluid Power – Contemporary Research, 1003–10. New Delhi: Springer India, 2016. http://dx.doi.org/10.1007/978-81-322-2743-4_94.

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Atti di convegni sul tema "Lattice Boltzmann scheme"

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Seta, Takeshi, Kenichi Okui e Eisyun Takegoshi. "Lattice Boltzmann Simulation of Nucleation". In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45163.

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We propose a lattice Boltzmann model capable of simulating nucleation. This LBM modifies a pseudo-potential so that it recovers a full set of hydrodynamic equations for two-phase flows based on the van der Waals-Cahn-Hilliard free energy theory through the Chapman-Enskog expansion procedure. Numerical measurements of thermal conductivity and of surface tension agree well with theoretical predictions. Simulations of phase transition, nucleation, pool boiling are carried out. They demonstrate that the model is applicable to two-phase flows with thermal effects. Using finite difference Lattice Boltzmann method ensures numerical stability of the scheme.

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Hsu, C. T., S. W. Chiang e K. F. Sin. "A Novel Dynamics Lattice Boltzmann Method for Gas Flows". In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-31237.

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The lattice Boltzmann method (LBM), where discrete velocities are specifically assigned to ensure that a particle leaves one lattice node always resides on another lattice node, has been developed for decades as a powerful numerical tool to solve the Boltzmann equation for gas flows. The efficient implementation of LBM requires that the discrete velocities be isotropic and that the lattice nodes be homogeneous. These requirements restrict the applications of the currently-used LBM schemes to incompressible and isothermal flows. Such restrictions defy the original physics of Boltzmann equation. Much effort has been devoted in the past decades to remove these restrictions, but of less success. In this paper, a novel dynamic lattice Boltzmann method (DLBM) that is free of the incompressible and isothermal restrictions is proposed and developed to simulate gas flows. This is achieved through a coordinate transformation featured with Galilean translation and thermal normalization. The transformation renders the normalized Maxwell equilibrium distribution with directional isotropy and spatial homogeneity for the accurate and efficient implementation of the Gaussian-Hermite quadrature. The transformed Boltzmann equation contains additional terms due to local convection and acceleration. The velocity quadrature points in the new coordinate system are fixed while the correspondent points in the physical space change from time to time and from position to position. By this dynamic quadrature nature in the physical space, we term this new scheme as the dynamic quadrature scheme. The lattice Boltzmann method (LBM) with the dynamic quadrature scheme is named as the dynamic lattice Boltzmann method (DLBM). The transformed Boltzmann equation is then solved in the new coordinate system based on the fixed quadrature points. Validations of the DLBM have been carried with several benchmark problems. Cavity flows problem are used. Excellent agreements are obtained as compared with those obtained from the conventional schemes. Up to date, the DLBM algorithm can run up to Mach number at 0.3 without suffering from numerical instability. The application of the DLBM to the Rayleigh-Bernard thermal instability problem is illustrated, where the onset of 2D vortex rolls and 3D hexagonal cells are well-predicted and are in excellent agreement with the theory. In summary, a novel dynamic lattice Boltzmann method (DLBM) has been proposed with algorithm developed for numerical simulation of gas flows. This new DLBM has been demonstrated to have removed the incompressible and isothermal restrictions encountered by the traditional LBM.

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Ubertini, Stefano. "Computational Fluid Dynamics Through an Unstructured Lattice Boltzmann Scheme". In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41194.

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Computational fluid dynamics, in its conventional meaning, computes pertinent flow fields in terms of velocity, density, pressure and temperature by numerically solving the Navier-Stokes equations in time and space. At the turn of the 1980s, the Lattice Boltzmann Method (LBM) has been proposed as an alternative approach to solve fluid dynamics problems and due to the refinements and the extensions of the last years, it has been used to successfully compute a number of nontrivial fluid dynamics problems, from incompressible turbulence to multiphase flow and bubble flow simulations. The most severe limitation of the original method is the uniform Cartesian grid on which the LBM must be constructed, that requires the approximation of a curved solid boundary by a series of stair steps. This represents a particularly severe limitation for practical engineering purposes especially when there is a need for high resolutions near the body or the walls. Among the recent advances in lattice Boltzmann research that have lead to substantial enhancement of the capabilities of the method to handle complex geometries, a particularly remarkable option is represented by changing the solution procedure from the original “stream and collide” to a finite volume technique. This paper presents a compact and efficient finite-volume lattice Boltzmann formulation on unstructured grids based on a cell-vertex scheme recently proposed in literature to integrate the differential form of the lattice Boltzmann equation. It is shown that the method tolerates significant grid distortions without showing any appreciable numerical viscosity effects at second order in the mesh size, thus allowing a time-accurate description of transitional flows. Moreover, a new set of boundary conditions to handle flows with open boundaries is presented. The resulting model has been tested against typical flow problems at low and moderate Reynolds numbers.

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Kravets, Bogdan, Muhammad S. Khan e Harald Kruggel-Emden. "Development and application of a thermal lattice Boltzmann scheme". In PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON NUMERICAL ANALYSIS AND APPLIED MATHEMATICS 2014 (ICNAAM-2014). AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4912623.

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Kamali, R., e A. H. Tabatabaee Frad. "Simulation of Hypersonic Viscous Flow Past a 2D Circular Cylinder Using Lattice Boltzmann Method". In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30482.

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It is known that the Lattice Boltzmann Method is not very effective when it is being used for the high speed compressible viscous flows; especially complex fluid flows around bodies. Different reasons have been reported for this unsuccessfulness; Lacking in required isotropy in the employed lattices and the restriction of having low Mach number in Taylor expansion of the Maxwell Boltzmann distribution as the equilibrium distribution function, might be mentioned as the most important ones. In present study, a new numerical method based on Li et al. scheme is introduced which enables the Lattice BoltzmannMethod to stably simulate the complex flows around a 2D circular cylinder. Furthermore, more stable implementation of boundary conditions in Lattice Boltzmann method is discussed.

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Fu, S. C., W. W. F. Leung e R. M. C. So. "A Lattice Boltzmann Method Based Numerical Scheme for Microchannel Flows". In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67654.

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Lattice Boltzmann method (LBM) has been recently developed into an alternative and promising numerical scheme for modeling fluid physics and fluid flows. The equation is hyperbolic and can be solved locally, explicitly, and efficiently on parallel computers. LBM has been applied to different types of complex flows with varying degree of success, but rarely to micro-scale flow. Due to its small scale, micro-channel flow exhibits many interesting phenomena that are not observed in its macro-scale counterpart. It is known that the Navier-Stokes equations can still be used to treat micro-channel flows if a slip wall boundary condition is assumed. The setting of boundary conditions in LBM has been a difficult task, and reliable boundary setting methods are limited. This paper reports on the development of an algorithm to solve the Boltzmann equation with a splitting method that allows the application of a slip wall boundary condition. Moreover, the fluid viscosity is accounted for as an additional term in the equilibrium particle distribution function, which offers the ability to simulate both Newtonian and non-Newtonian fluids. An LBM based numerical scheme, which is suitable for micro-channel flows, is proposed. A two-dimensional nine-velocity lattice model is developed for the numerical simulation. Validation of the numerical scheme is carried out against micro-channel, micro-tube and driven cavity flows, and excellent agreement is obtained between numerical calculations and analytical solutions of these flows.

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Ma, Yu, Yahui Wang, Kuilong Song e Qian Sun. "Adaptive Mesh Refinement for Neutron Transfer With Lattice Boltzmann Scheme". In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-66093.

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This paper presents a novel lattice Boltzmann (LB) model for neutron transfer and a block-structured adaptive-mesh-refinement (SAMR) technique for proposed LB model. By discretizing the general Boltzmann equation, the LB model for neutron transfer is established and the corresponding parameters are obtained. The SAMR technique removes the requirement of tree-type data structure in traditional adaptive-mesh-refinement technique and adjusts the time step adaptively and identically in all blocks. By applying the node-type distribution function, the needs for rescaling the distribution functions is eliminated. To solve the discontinuities of scalar flux at fine-coarse blocks interface, a novel technique is presented which treats the inner boundary condition by streaming process of LB method. Simulation results show good accuracy and efficiency of the proposed neutron LB model with SAMR technique. This paper may provide a powerful technique for large engineering calculation.

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Ye Zhao. "GPU-accelerated surface denoising and morphing with lattice Boltzmann scheme". In 2008 IEEE International Conference on Shape Modeling and Applications (SMI). IEEE, 2008. http://dx.doi.org/10.1109/smi.2008.4547942.

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Sun, Xiuyu, Zhiqiang Wang e George Chen. "Parallel active contour with Lattice Boltzmann scheme on modern GPU". In 2012 19th IEEE International Conference on Image Processing (ICIP 2012). IEEE, 2012. http://dx.doi.org/10.1109/icip.2012.6467208.

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Mikheev, Sergei A., e Gerasim V. Krivovichev. "Numerical analysis of two-step finite-difference-based lattice Boltzmann scheme". In 2014 International Conference on Computer Technologies in Physical and Engineering Applications (ICCTPEA). IEEE, 2014. http://dx.doi.org/10.1109/icctpea.2014.6893313.

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