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Artigos de revistas sobre o tema "Multiscale flow"

Autor: Grafiati

Publicado: 19 de outubro de 2024

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1

Sindeev, S. V., S. V. Frolov, D. Liepsch e A. Balasso. "MODELING OF FLOW ALTERATIONS INDUCED BY FLOW-DIVERTER USING MULTISCALE MODEL OF HEMODYNAMICS". Vestnik Tambovskogo gosudarstvennogo tehnicheskogo universiteta 23, n.º 1 (2017): 025–32. http://dx.doi.org/10.17277/vestnik.2017.01.pp.025-032.

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2

Koumoutsakos, Petros. "MULTISCALE FLOW SIMULATIONS USING PARTICLES". Annual Review of Fluid Mechanics 37, n.º 1 (janeiro de 2005): 457–87. http://dx.doi.org/10.1146/annurev.fluid.37.061903.175753.

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3

SHENG, MAO, GENSHENG LI, SHOUCENG TIAN, ZHONGWEI HUANG e LIQIANG CHEN. "A FRACTAL PERMEABILITY MODEL FOR SHALE MATRIX WITH MULTI-SCALE POROUS STRUCTURE". Fractals 24, n.º 01 (março de 2016): 1650002. http://dx.doi.org/10.1142/s0218348x1650002x.

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Nanopore structure and its multiscale feature significantly affect the shale-gas permeability. This paper employs fractal theory to build a shale-gas permeability model, particularly considering the effects of multiscale flow within a multiscale pore space. Contrary to previous studies which assume a bundle of capillary tubes with equal size, in this research, this model reflects various flow regimes that occur in multiscale pores and takes the measured pore-size distribution into account. The flow regime within different scales is individually determined by the Knudsen number. The gas permeability is an integral value of individual permeabilities contributed from pores of different scales. Through comparing the results of five shale samples, it is confirmed that the gas permeability varies with the pore-size distribution of the samples, even though their intrinsic permeabilities are the same. Due to consideration of multiscale flow, the change of gas permeability with pore pressure becomes more complex. Consequently, it is necessary to cover the effects of multiscale flow while determining shale-gas permeability.

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4

Zhou, Hui, e Hamdi A. Tchelepi. "Operator-Based Multiscale Method for Compressible Flow". SPE Journal 13, n.º 02 (1 de junho de 2008): 267–73. http://dx.doi.org/10.2118/106254-pa.

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Summary Multiscale methods have been developed for accurate and efficient numerical solution of flow problems in large-scale heterogeneous reservoirs. A scalable and extendible Operator-Based Multiscale Method (OBMM) is described here. OBMM is cast as a general algebraic framework. It is natural and convenient to incorporate more physics in OBMM for multiscale computation. In OBMM, two operators are constructed: prolongation and restriction. The prolongation operator is constructed by assembling the multiscale basis functions. The specific form of the restriction operator depends on the coarse-scale discretization formulation (e.g., finitevolume or finite-element). The coarse-scale pressure equation is obtained algebraically by applying the prolongation and restriction operators to the fine-scale flow equations. Solving the coarse-scale equation results in a high-quality coarse-scale pressure. The finescale pressure can be reconstructed by applying the prolongation operator to the coarse-scale pressure. A conservative fine-scale velocity field is then reconstructed to solve the transport (saturation) equation. We describe the OBMM approach for multiscale modeling of compressible multiphase flow. We show that extension from incompressible to compressible flows is straightforward. No special treatment for compressibility is required. The efficiency of multiscale formulations over standard fine-scale methods is retained by OBMM. The accuracy of OBMM is demonstrated using several numerical examples including a challenging depletion problem in a strongly heterogeneous permeability field (SPE 10). Introduction The accuracy of simulating subsurface flow relies strongly on the detailed geologic description of the porous formation. Formation properties such as porosity and permeability typically vary over many scales. As a result, it is not unusual for a detailed geologic description to require 107-108 grid cells. However, this level of resolution is far beyond the computational capability of state-of-the-art reservoir simulators (106 grid cells). Moreover, in many applications, large numbers of reservoir simulations are performed (e.g., history matching, sensitivity analysis and stochastic simulation). Thus, it is necessary to have an efficient and accurate computational method to study these highly detailed models. Multiscale formulations are very promising due to their ability to resolve fine-scale information accurately without direct solution of the global fine-scale equations. Recently, there has been increasing interest in multiscale methods. Hou and Wu (1997) proposed a multiscale finite-element method (MsFEM) that captures the fine-scale information by constructing special basis functions within each element. However, the reconstructed fine-scale velocity is not conservative. Later, Chen and Hou (2003) proposed a conservative mixed finite-element multiscale method. Another multiscale mixed finite element method was presented by Arbogast (2002) and Arbogast and Bryant (2002). Numerical Green functions were used to resolve the fine-scale information, which are then coupled with coarse-scale operators to obtain the global solution. Aarnes (2004) proposed a modified mixed finite-element method, which constructs special basis functions sensitive to the nature of the elliptic problem. Chen et al. (2003) developed a local-global upscaling method by extracting local boundary conditions from a global solution, and then constructing coarse-scale system from local solutions. All these methods considered incompressible flow in heterogeneous porous media where the pressure equation is elliptic. A multiscale finite-volume method (MsFVM) was proposed by Jenny et al. (2003, 2004, 2006) for heterogeneous elliptic problems. They employed two sets of basis functions--dual and primal. The dual basis functions are identical to those of Hou and Wu (1997), while the primal basis functions are obtained by solving local elliptic problems with Neumann boundary conditions calculated from the dual basis functions. Existing multiscale methods (Aarnes 2004; Arbogast 2002; Chen and Hou 2003; Hou and Wu 1997; Jenny et al. 2003) deal with the incompressible flow problem only. However, compressibility will be significant if a gas phase is present. Gas has a large compressibility, which is a strong function of pressure. Therefore, there can be significant spatial compressibility variations in the reservoir, and this is a challenge for multiscale modeling. Very recently, Lunati and Jenny (2006) considered compressible multiphase flow in the framework of MsFVM. They proposed three models to account for the effects of compressibility. Using those models, compressibility effects were represented in the coarse-scale equations and the reconstructed fine-scale fluxes according to the magnitude of compressibility. Motivated to construct a flexible algebraic multiscale framework that can deal with compressible multiphase flow in highly detailed heterogeneous models, we developed an operator-based multiscale method (OBMM). The OBMM algorithm is composed of four steps:constructing the prolongation and restriction operators,assembling and solving the coarse-scale pressure equations,reconstructing the fine-scale pressure and velocity fields, andsolving the fine-scale transport equations. OBMM is a general algebraic multiscale framework for compressible multiphase flow. This algebraic framework can also be extended naturally from structured to unstructured grid. Moreover, the OBMM approach may be used to employ multiscale solution strategies in existing simulators with a relatively small investment.

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5

Liu, Zhongqiu. "Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting". Metals 12, n.º 5 (27 de abril de 2022): 746. http://dx.doi.org/10.3390/met12050746.

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6

Zhou, H., S. H. H. Lee e H. A. A. Tchelepi. "Multiscale Finite-Volume Formulation for the Saturation Equations". SPE Journal 17, n.º 01 (12 de dezembro de 2011): 198–211. http://dx.doi.org/10.2118/119183-pa.

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Summary Recent advances in multiscale methods have shown great promise in modeling multiphase flow in highly detailed heterogeneous domains. Existing multiscale methods, however, solve for the flow field (pressure and total velocity) only. Once the fine-scale flow field is reconstructed, the saturation equations are solved on the fine scale. With the efficiency in dealing with the flow equations greatly improved by multiscale formulations, solving the saturation equations on the fine scale becomes the relatively more expensive part. In this paper, we describe an adaptive multiscale finite-volume (MSFV) formulation for nonlinear transport (saturation) equations. A general algebraic multiscale formulation consistent with the operator-based framework proposed by Zhou and Tchelepi (SPE Journal, June 2008, pages 267–273) is presented. Thus, the flow and transport equations are solved in a unified multiscale framework. Two types of multiscale operators—namely, restriction and prolongation—are used to construct the multiscale saturation solution. The restriction operator is defined as the sum of the fine-scale transport equations in a coarse gridblock. Three adaptive prolongation operators are defined according to the local saturation history at a particular coarse block. The three operators have different computational complexities, and they are used adaptively in the course of a simulation run. When properly used, they yield excellent computational efficiency while preserving accuracy. This adaptive multiscale formulation has been tested using several challenging problems with strong heterogeneity, large buoyancy effects, and changes in the well operating conditions (e.g., switching injectors and producers during simulation). The results demonstrate that adaptive multiscale transport calculations are in excellent agreement with fine-scale reference solutions, but at a much lower computational cost.

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Cui, Zhanyou, Gaoli Chen, Bing Liu e Deguang Li. "A Multiscale Symbolic Dynamic Entropy Analysis of Traﬃc Flow". Journal of Advanced Transportation 2022 (30 de março de 2022): 1–10. http://dx.doi.org/10.1155/2022/8389229.

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The complexity analysis of traffic flow is important for understanding the property of traffic system. Being good at analyzing the regularity and complexity, multiscale SamEn has attracted much attention and many methods have been proposed for complexity analysis of traffic flow. However, there may exist discontinuity of the calculated entropy value which makes the regularity of the traffic system difficult to understand. The phenomenon occurs due to an inappropriate selection of the parameter r in the multiscale SamEn. Moreover, it is diﬃcult to select an appropriate r for the accurate evaluation of the complexity, which limits the application of multiscale entropy for traffic flow analysis. To solve this problem, a new entropy-based method, multiscale symbolic dynamic entropy, for evaluating the traﬃc system is proposed here. To verify the eﬀectiveness of the proposed method, traﬃc data collected from stations in diﬀerent cities are preprocessed by the proposed method. Both results of two cases show that the weekend patterns and weekday patterns are eﬀectively distinguished using the proposed method, respectively. Speciﬁcally, compared with the traditional methods including multiscale SamEn and the multiscale modiﬁed SamEn, the complexity of the corresponding traﬃc system can be better evaluated without considering the selection of r, which demonstrates the eﬀectiveness of the proposed method.

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8

Bazilevs, Yuri, Kenji Takizawa e Tayfun E. Tezduyar. "Computational analysis methods for complex unsteady flow problems". Mathematical Models and Methods in Applied Sciences 29, n.º 05 (maio de 2019): 825–38. http://dx.doi.org/10.1142/s0218202519020020.

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In this lead paper of the special issue, we provide a brief summary of the stabilized and multiscale methods in fluid dynamics. We highlight the key features of the stabilized and multiscale scale methods, and variational methods in general, that make these approaches well suited for computational analysis of complex, unsteady flows encountered in modern science and engineering applications. We mainly focus on the recent developments. We discuss application of the variational multiscale (VMS) methods to fluid dynamics problems involving computational challenges associated with high-Reynolds-number flows, wall-bounded turbulent flows, flows on moving domains including subdomains in relative motion, fluid–structure interaction (FSI), and complex-fluid flows with FSI.

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9

Mäkipere, Krista, e Piroz Zamankhan. "Simulation of Fiber Suspensions—A Multiscale Approach". Journal of Fluids Engineering 129, n.º 4 (18 de agosto de 2006): 446–56. http://dx.doi.org/10.1115/1.2567952.

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The present effort is the development of a multiscale modeling, simulation methodology for investigating complex phenomena arising from flowing fiber suspensions. The present approach is capable of coupling behaviors from the Kolmogorov turbulence scale through the full-scale system in which a fiber suspension is flowing. Here the key aspect is adaptive hierarchical modeling. Numerical results are presented for which focus is on fiber floc formation and destruction by hydrodynamic forces in turbulent flows. Specific consideration was given to dynamic simulations of viscoelastic fibers in which the fluid flow is predicted by a method that is a hybrid between direct numerical simulations and large eddy simulation techniques and fluid fibrous structure interactions will be taken into account. Dynamics of simple fiber networks in a shearing flow of water in a channel flow illustrate that the shear-induced bending of the fiber network is enhanced near the walls. Fiber-fiber interaction in straight ducts is also investigated and results show that deformations would be expected during the collision when the surfaces of flocs will be at contact. Smaller velocity magnitudes of the separated fibers compare to the velocity before collision implies the occurrence of an inelastic collision. In addition because of separation of vortices, interference flows around two flocs become very complicated. The results obtained may elucidate the physics behind the breakup of a fiber floc, opening the possibility for developing a meaningful numerical model of the fiber flow at the continuum level where an Eulerian multiphase flow model can be developed for industrial use.

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Lorenz, Eric, e Alfons G. Hoekstra. "Heterogeneous Multiscale Simulations of Suspension Flow". Multiscale Modeling & Simulation 9, n.º 4 (outubro de 2011): 1301–26. http://dx.doi.org/10.1137/100818522.

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Davy, P., O. Bour, J. R. De Dreuzy e C. Darcel. "Flow in multiscale fractal fracture networks". Geological Society, London, Special Publications 261, n.º 1 (2006): 31–45. http://dx.doi.org/10.1144/gsl.sp.2006.261.01.03.

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12

WANG, Chao, e Yongbin ZHANG. "Multiscale Elastohydrodynamic Wedge-Platform Thrust Bearing with Ultra Low Clearance". Mechanics 30, n.º 1 (23 de fevereiro de 2024): 23–28. http://dx.doi.org/10.5755/j02.mech.34137.

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The effect of the surface elastic deformation is investigated by the multiscale approach in the hydrodynamic wedge-platform thrust bearing with the ultra low clearance on the 1nm scale, by incorporating both the non-continuum pure adsorbed layer flow and the multiscale “sandwich” film flow. The pure adsorbed layer flow in ultra small surface separations is described by the non-continuum nanoscale flow equation; The “sandwich” film flow is described by the multiscale flow equations respectively for the adsorbed layer flow and the intermediate continuum fluid flow. The numerical calculation results show that in the studied bearing, the effect of the surface elastic deformation is normally significant, it pronouncedly reduces the maximum film pressure, greatly changes both the film pressure profile and the surface separation profile, and considerably increases the minimum surface separation, which occurs on the exit of the bearing. The effect of the surface elastic deformation is shown to be obviously dependent on the fluid-bearing surface interaction.

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13

Krogstad, S., V. L. L. Hauge e A. F. F. Gulbransen. "Adjoint Multiscale Mixed Finite Elements". SPE Journal 16, n.º 01 (23 de agosto de 2010): 162–71. http://dx.doi.org/10.2118/119112-pa.

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Summary We develop an adjoint model for a simulator consisting of a multiscale pressure solver and a saturation solver that works on flow-adapted grids. The multiscale method solves the pressure on a coarse grid that is close to uniform in index space and incorporates fine-grid effects through numerically computed basis functions. The transport solver works on a coarse grid adapted by a fine-grid velocity field obtained by the multiscale solver. Both the multiscale solver for pressure and the flow-based coarsening approach for transport have shown earlier the ability to produce accurate results for a high degree of coarsening. We present results for a complex realistic model to demonstrate that control settings based on optimization of our multiscale flow-based model closely match or even outperform those found by using a fine-grid model. For additional speed-up, we develop mappings used for rapid system updates during the timestepping procedure. As a result, no fine-grid quantities are required during simulations and all fine-grid computations (multiscale basis functions, generation of coarse transport grid, and coarse mappings) become a preprocessing step. The combined methodology enables optimization of waterflooding on a complex model with 45,000 grid cells in a few minutes.

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Gulbransen, Astrid Fossum, Vera Louise Hauge e Knut-Andreas Lie. "A Multiscale Mixed Finite-Element Method for Vuggy and Naturally Fractured Reservoirs". SPE Journal 15, n.º 02 (17 de dezembro de 2009): 395–403. http://dx.doi.org/10.2118/119104-pa.

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Summary Vugs, caves, and fractures can alter the effective permeability of carbonate reservoirs significantly and should be accounted for accurately in a geomodel. Accurate modeling of the interaction between free-flow and porous regions is essential for flow simulations and detailed production-engineering calculations. However, flow simulation of such reservoirs is very challenging because of the coexistence of porous and free-flow regions on multiple scales that need to be coupled. Multiscale methods are conceptually well-suited for this type of modeling because they allow varying resolution and provide a systematic procedure for coarsening and refinement. However, to date there are hardly any multiscale methods developed for problems with both free-flow and porous regions. Herein, we develop a multiscale mixed finite-element (MsMFE) method for detailed modeling of vuggy and naturally fractured reservoirs as a first step toward a uniform multiscale, multiphysics framework. The MsMFE method uses a standard Darcy model to approximate pressure and fluxes on a coarse grid, whereas fine-scale effects are captured through basis functions computed numerically by solving local Stokes-Brinkman flow problems on the underlying fine-scale geocellular grid. The Stokes-Brinkman equations give a unified approach to simulating free-flow and porous regions using a single system of equations, they avoid explicit interface modeling, and they reduce to Darcy or Stokes flow in certain parameter limits. In this paper, the MsMFE solutions are compared with finescale Stokes-Brinkman solutions for test cases including both short- and long-range fractures. The results demonstrate how fine-scale flow in fracture networks can be represented within a coarse-scale Darcy-flow model by using multiscale elements computed solving the Stokes-Brinkman equations. The results indicate that the MsMFE method is a promising path toward direct simulation of highly detailed geocellular models of vuggy and naturally fractured reservoirs.

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LESCHZINER, M. A., G. M. FISHPOOL e S. LARDEAU. "TURBULENT SHEAR FLOW: A PARADIGMATIC MULTISCALE PHENOMENON". Journal of Multiscale Modelling 01, n.º 02 (abril de 2009): 197–222. http://dx.doi.org/10.1142/s1756973709000104.

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The paper provides a broad discussion of multiscale and structural features of sheared turbulent flows. Basic phenomenological aspects of turbulence are first introduced, largely in descriptive terms with particular emphasis placed on the range of scales encountered in turbulent flows and in the identification of characteristic scale ranges. There follows a discussion of essential aspects of computational modeling and simulation of turbulence. Finally, the results of simulations for two groups of flows are discussed. These combine shear, separation, and periodicity, the last feature provoked by either a natural instability or by unsteady external forcing. The particular choice of examples is intended to illustrate the capabilities of such simulations to resolve the multiscale nature of complex turbulent flows, as well as the challenges encountered.

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Meng, Du, Chen Xiao-yan, Liu Hong-ying, He Qing, Bai Rui-xiang, Liu Weixin e Li Zewei. "Time Irreversibility from Time Series for Analyzing Oil-in-Water Flow Transition". Mathematical Problems in Engineering 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/2879524.

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We first experimentally collect conductance fluctuation signals of oil-in-water two-phase flow in a vertical pipe. Then we detect the flow pattern asymmetry character from the collected signals with multidimensional time irreversibility and multiscale time irreversibility index. Moreover, we propose a novel criterion, that is, AMSI (average of multiscale time irreversibility), to quantitatively investigate the oil-in-water two-phase flow pattern dynamics. The results show that AMSI is sensitive to the flow pattern evolution that can be used to predict the flow pattern transition and bubble coalescence.

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17

Alpak, Faruk O., Mayur Pal e Knut-Andreas Lie. "A Multiscale Adaptive Local-Global Method for Modeling Flow in Stratigraphically Complex Reservoirs". SPE Journal 17, n.º 04 (28 de novembro de 2012): 1056–70. http://dx.doi.org/10.2118/140403-pa.

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Summary A robust and efficient simulation technique is developed on the basis of the extension of the mimetic finite-difference method (MFDM) to multiscale hierarchical-hexahedral (corner-point) grids by use of the multiscale mixed finite-element method (MsMFEM). The implementation of the mimetic subgrid-discretization method is compact and generic for a large class of grids and, thereby, is suitable for discretizations of reservoir models with complex geologic architecture. Flow equations are solved on a coarse grid where basis functions with subgrid resolution account accurately for subscale variations from an underlying fine-scale geomodel. The method relies on the construction of approximate velocity spaces that are adaptive to the local properties of the differential operator. A variant of the method for computing velocity basis functions is developed that uses an adaptive local-global (ALG) algorithm to compute multiscale velocity basis functions by capturing the principal characteristics of global flow. Both local and local-global methods generate subgrid-scale velocity fields that reproduce the impact of fine-scale stratigraphic architecture. By using multiscale basis functions to discretize the flow equations on a coarse grid, one can retain the efficiency of an upscaling method, while at the same time produce detailed and conservative velocity fields on the underlying fine grid. The accuracy and efficacy of the multiscale method is compared with those of fine-scale models and of coarse-scale models with no subgrid treatment for several two-phase-flow scenarios. Numerical experiments involving two-phase incompressible flow and transport phenomena are carried out on high-resolution corner-point grids that represent explicitly example stratigraphic architectures found in real-life shallow-marine and turbidite reservoirs. The multiscale method is several times faster than the direct solution of the fine-scale problem and yields more accurate solutions than coarse-scale modeling techniques that resort to explicit effective properties. The accuracy of the multiscale simulation method with ALG-velocity basis functions is compared with that of the local velocity basis functions. The multiscale simulation results are consistently more accurate when the local-global method is employed for computing the velocity basis functions.

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Dinh, T. N., R. R. Nourgaliev e T. G. Theofanous. "ON THE MULTISCALE TREATMENT OF MULTIFLUID FLOW". Multiphase Science and Technology 15, n.º 1-4 (2003): 275–88. http://dx.doi.org/10.1615/multscientechn.v15.i1-4.210.

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19

Hilton, James E., e Paul W. Cleary. "A MULTISCALE METHOD FOR GEOPHYSICAL FLOW EVENTS". International Journal for Multiscale Computational Engineering 10, n.º 4 (2012): 375–90. http://dx.doi.org/10.1615/intjmultcompeng.2012003264.

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Chipperfield, A. J., M. Thanaj e G. F. Clough. "Multiscale, multidomain analysis of microvascular flow dynamics". Experimental Physiology 105, n.º 9 (7 de fevereiro de 2020): 1452–58. http://dx.doi.org/10.1113/ep087874.

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21

Joueiai, Mahtab, Hans van Lint e Serge P. Hoogendoom. "Multiscale Traffic Flow Modeling in Mixed Networks". Transportation Research Record: Journal of the Transportation Research Board 2421, n.º 1 (janeiro de 2014): 142–50. http://dx.doi.org/10.3141/2421-16.

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22

Bello-Ochende, T., J. P. Meyer e O. I. Ogunronbi. "Constructal multiscale cylinders rotating in cross-flow". International Journal of Heat and Mass Transfer 54, n.º 11-12 (maio de 2011): 2568–77. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2011.02.004.

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23

Peng, Zhangli, Robert J. Asaro e Qiang Zhu. "Multiscale modelling of erythrocytes in Stokes flow". Journal of Fluid Mechanics 686 (29 de setembro de 2011): 299–337. http://dx.doi.org/10.1017/jfm.2011.332.

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AbstractTo quantitatively understand the correlation between the molecular structure of an erythrocyte (red blood cell, RBC) and its mechanical response, and to predict mechanically induced structural remodelling in physiological conditions, we developed a computational model by coupling a multiscale approach of RBC membranes with a boundary element method (BEM) for surrounding Stokes flows. The membrane is depicted at three levels: in the whole cell level, a finite element method (FEM) is employed to model the lipid bilayer and the cytoskeleton as two distinct layers of continuum shells. The mechanical properties of the cytoskeleton are obtained from a molecular-detailed model of the junctional complex. The spectrin, a major protein of the cytoskeleton, is simulated using a molecular-based constitutive model. The BEM model is coupled with the FEM model through a staggered coupling algorithm. Using this technique, we first simulated RBC dynamics in capillary flow and found that the protein density variation and bilayer–skeleton interaction forces are much lower than those in micropipette aspiration, and the maximum interaction force occurs at the trailing edge. Then we investigated mechanical responses of RBCs in shear flow during tumbling, tank-treading and swinging motions. The dependencies of tank-treading frequency on the blood plasma viscosity and the membrane viscosity we found match well with benchmark data. The simulation results show that during tank-treading the protein density variation is insignificant for healthy erythrocytes, but significant for cells with a smaller bilayer–skeleton friction coefficient, which may be the case in hereditary spherocytosis.

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Aldredge, R. C. "Flame propagation in multiscale transient periodic flow". Combustion and Flame 183 (setembro de 2017): 166–80. http://dx.doi.org/10.1016/j.combustflame.2017.05.012.

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25

Hou, Thomas Y. "Multiscale modelling and computation of fluid flow". International Journal for Numerical Methods in Fluids 47, n.º 8-9 (2005): 707–19. http://dx.doi.org/10.1002/fld.866.

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BABOVSKY, HANS. "A KINETIC MULTISCALE MODEL". Mathematical Models and Methods in Applied Sciences 12, n.º 03 (março de 2002): 309–31. http://dx.doi.org/10.1142/s0218202502001611.

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We derive a system of kinetic equations which realize the Broadwell model on a variety of scales. For a 16-velocity model we verify constraints giving rise to "realistic" Euler equations. Applications to rarefied flow dynamics are developed.

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Spiridonov, Denis, Maria Vasilyeva, Eric T. Chung, Yalchin Efendiev e Raghavendra Jana. "Multiscale Model Reduction of the Unsaturated Flow Problem in Heterogeneous Porous Media with Rough Surface Topography". Mathematics 8, n.º 6 (3 de junho de 2020): 904. http://dx.doi.org/10.3390/math8060904.

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In this paper, we consider unsaturated filtration in heterogeneous porous media with rough surface topography. The surface topography plays an important role in determining the flow process and includes multiscale features. The mathematical model is based on the Richards’ equation with three different types of boundary conditions on the surface: Dirichlet, Neumann, and Robin boundary conditions. For coarse-grid discretization, the Generalized Multiscale Finite Element Method (GMsFEM) is used. Multiscale basis functions that incorporate small scale heterogeneities into the basis functions are constructed. To treat rough boundaries, we construct additional basis functions to take into account the influence of boundary conditions on rough surfaces. We present numerical results for two-dimensional and three-dimensional model problems. To verify the obtained results, we calculate relative errors between the multiscale and reference (fine-grid) solutions for different numbers of multiscale basis functions. We obtain a good agreement between fine-grid and coarse-grid solutions.

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Zhang, Lianfa, Jianquan Cheng, Cheng Jin e Hong Zhou. "A Multiscale Flow-Focused Geographically Weighted Regression Modelling Approach and Its Application for Transport Flows on Expressways". Applied Sciences 9, n.º 21 (2 de novembro de 2019): 4673. http://dx.doi.org/10.3390/app9214673.

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Scale is a fundamental geographical concept and its role in different geographical contexts has been widely documented. The increasing availability of transport mobility data, in the form of big datasets, enables further incorporation of spatial dependencies and non-stationarity into spatial interaction modeling of transport flows. In this paper a newly developed multiscale flow-focused geographically weighted regression (MFGWR) approach has been applied, in addition to global and local Moran I indices of flow data, to model multiscale socio-economic determinants of regional transport flows between counties across the Jiangsu Province in China. The results have confirmed the power of local Moran I of flow data for identifying urban agglomerations and the effectiveness of MFGWR in exploring multiscale processes of spatial interactions. A comparison between MFGWR and flow-focused geographically weighted regression (FGWR) showed that the MFGWR approach can better interpret the heterogeneous processes of spatial interaction.

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Graham, Richard S. "Modelling flow-induced crystallisation in polymers". Chem. Commun. 50, n.º 27 (2014): 3531–45. http://dx.doi.org/10.1039/c3cc49668f.

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A review of recent multiscale modelling of flow-induced crystallisation in polymers with a particular emphasis on newly emerging techniques to connect modelling and simulation techniques at different levels of coarse-graining.

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Górski, Grzegorz, Grzegorz Litak, Romuald Mosdorf e Andrzej Rysak. "Periodic Trends in Two-Phase Flow Through a Vertical Minichannel: Wavelet and Multiscale Entropy Analyses Based on Digital Camera Data". Acta Mechanica et Automatica 13, n.º 1 (1 de março de 2019): 51–56. http://dx.doi.org/10.2478/ama-2019-0008.

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Abstract By changing the air and water flow relative rates in the two-phase (air-water) flow through a minichannel, we observe aggregation and partitioning of air bubbles and slugs of different sizes. An air bubble arrangement, which show non-periodic and periodic patterns. The spatiotemporal behaviour was recorded by a digital camera. Multiscale entropy analysis is a method of measuring the time series complexity. The main aim of the paper was testing the possibility of implementation of multiscale entropy for two-phase flow patterns classification. For better understanding, the dynamics of the two-phase flow patterns inside the minichannel histograms and wavelet methods were also used. In particular, we found a clear distinction between bubbles and slugs formations in terms of multiscale entropy. On the other hand, the intermediate region was effected by appearance of both forms in non-periodic and periodic sequences. The preliminary results were confirmed by using histograms and wavelets.

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31

Zhang, Ping, e Xiaohua Zhang. "Numerical Modeling of Stokes Flow in a Circular Cavity by Variational Multiscale Element Free Galerkin Method". Mathematical Problems in Engineering 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/451546.

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The variational multiscale element free Galerkin method is extended to simulate the Stokes flow problems in a circular cavity as an irregular geometry. The method is combined with Hughes’s variational multiscale formulation and element free Galerkin method; thus it inherits the advantages of variational multiscale and meshless methods. Meanwhile, a simple technique is adopted to impose the essential boundary conditions which makes it easy to solve problems with complex area. Finally, two examples are solved and good results are obtained as compared with solutions of analytical and numerical methods, which demonstrates that the proposed method is an attractive approach for solving incompressible fluid flow problems in terms of accuracy and stability, even for complex irregular boundaries.

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Chung, Eric, Yalchin Efendiev, Wing Leung e Jun Ren. "Multiscale Simulations for Coupled Flow and Transport Using the Generalized Multiscale Finite Element Method". Computation 3, n.º 4 (11 de dezembro de 2015): 670–86. http://dx.doi.org/10.3390/computation3040670.

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TANG, Zhipeng, e Yongbin ZHANG. "Multiscale Analysis of the Performance of Micro/nano Porous Filtration Membranes with Double Concentric Cylindrical Pores: Part II-Optimization Results". Mechanics 28, n.º 3 (21 de junho de 2022): 217–21. http://dx.doi.org/10.5755/j02.mech.30509.

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The multiscale calculation results for the values of the optimized parameters are presented for the micro/nano porous filtration membranes with double concentric cylindrical pores where multiscale flows occur. For a weak liquid-pore wall interaction, the optimum ratio of the radius of the bigger pore to the radius of the smaller pore (i.e. the filtration pore) can be calculated from the classical equation, however the corresponding lowest flow resistance of the membrane should still be calculated from the multiscale analysis owing to the adsorbed layer effect when the ratio Landax of the thickness of the adsorbed layer to the radius of the smaller pore is greater than 0.1. For medium and strong liquid-pore wall interactions, the optimum ratios of the pore radii should be calculated from the multiscale analysis, and the corresponding lowest flow resistances of the membrane are much higher than the classical calculation showing the significant effect of the adsorbed layer when Landax>=0.1.

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Yu, Ying, Yu Xin Zuo, Peng Liu e Chun Cheng Zuo. "Multiscale Simulation of Liquid Flow in Nanofluidic Channel Coated with Polymer Brush". Advanced Materials Research 677 (março de 2013): 90–93. http://dx.doi.org/10.4028/www.scientific.net/amr.677.90.

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A Multiscale simulation method is used to study the liquid flow in nanofluidic channel coated with polymer brushes. Molecular dynamics (MD) simulation is introduced in the particle region and Navier-Stokes (NS) equations are applied in the remaining region where the continuum assumption is still valid. The effects of the shear rate and the number of polymer chains on the flow velocity are investigated. The velocities obtained from MD simulations in particle region are connected to the region of continuum. Our study demonstrates that the multiscale simulation method presented here is reasonable in exploring the liquid flow in nanochannel coated with polymer brushes.

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35

Rathinasamy, Maheswaran, e Rakesh Khosa. "Multiscale nonlinear model for monthly streamflow forecasting: a wavelet-based approach". Journal of Hydroinformatics 14, n.º 2 (22 de outubro de 2011): 424–42. http://dx.doi.org/10.2166/hydro.2011.130.

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The dynamics of the streamflow in rivers involve nonlinear and multiscale phenomena. An attempt is made to develop nonlinear models combining wavelet decomposition with Volterra models. This paper describes a methodology to develop one-month-ahead forecasts of streamflow using multiscale nonlinear models. The method uses the concept of multiresolution decomposition using wavelets in order to represent the underlying integrated streamflow dynamics and this information, across scales, is then linked together using the first- and second-order Volterra kernels. The model is applied to 30 river data series from the western USA. The mean monthly data series of 30 rivers are grouped under the categories low, medium and high. The study indicated the presence of multiscale phenomena and discernable nonlinear characteristics in the streamflow data. Detailed analyses and results are presented only for three stations, selected to represent the low-flow, medium-flow and high-flow categories, respectively. The proposed model performance is good for all the flow regimes when compared with both the ARMA-type models as well as nonlinear models based on chaos theory.

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LAIZET, S., e J. C. VASSILICOS. "MULTISCALE GENERATION OF TURBULENCE". Journal of Multiscale Modelling 01, n.º 01 (janeiro de 2009): 177–96. http://dx.doi.org/10.1142/s1756973709000098.

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This paper presents a brief but general introduction to the physics and engineering of fractals, followed by a brief introduction to fluid turbulence generated by multiscale flow actuation. Numerical computations of such turbulent flows are now beginning to be possible because of the immersed boundary method (IBM) and terascale parallel high performance computing capabilities. The first-ever direct numerical simulation (DNS) results of turbulence generated by fractal grids are detailed and compared with recent wind tunnel measurements.

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37

Ren, Jinlian, Peirong Lu, Tao Jiang, Jianfeng Liu e Weigang Lu. "A flexible multiscale algorithm based on an improved smoothed particle hydrodynamics method for complex viscoelastic flows". Applied Mathematics and Mechanics 45, n.º 8 (27 de julho de 2024): 1387–402. http://dx.doi.org/10.1007/s10483-024-3134-9.

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AbstractViscoelastic flows play an important role in numerous engineering fields, and the multiscale algorithms for simulating viscoelastic flows have received significant attention in order to deepen our understanding of the nonlinear dynamic behaviors of viscoelastic fluids. However, traditional grid-based multiscale methods are confined to simple viscoelastic flows with short relaxation time, and there is a lack of uniform multiscale scheme available for coupling different solvers in the simulations of viscoelastic fluids. In this paper, a universal multiscale method coupling an improved smoothed particle hydrodynamics (SPH) and multiscale universal interface (MUI) library is presented for viscoelastic flows. The proposed multiscale method builds on an improved SPH method and leverages the MUI library to facilitate the exchange of information among different solvers in the overlapping domain. We test the capability and flexibility of the presented multiscale method to deal with complex viscoelastic flows by solving different multiscale problems of viscoelastic flows. In the first example, the simulation of a viscoelastic Poiseuille flow is carried out by two coupled improved SPH methods with different spatial resolutions. The effects of exchanging different physical quantities on the numerical results in both the upper and lower domains are also investigated as well as the absolute errors in the overlapping domain. In the second example, the complex Wannier flow with different Weissenberg numbers is further simulated by two improved SPH methods and coupling the improved SPH method and the dissipative particle dynamics (DPD) method. The numerical results show that the physical quantities for viscoelastic flows obtained by the presented multiscale method are in consistence with those obtained by a single solver in the overlapping domain. Moreover, transferring different physical quantities has an important effect on the numerical results.

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Correia, Manuel Gomes, João Carlos von Hohendorff Filho e Denis José Schiozer. "Multiscale Integration for Karst-Reservoir Flow-Simulation Models". SPE Reservoir Evaluation & Engineering 23, n.º 02 (1 de maio de 2020): 518–33. http://dx.doi.org/10.2118/195545-pa.

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Leung, Wing Tat, e Yating Wang. "Multirate Partially Explicit Scheme for Multiscale Flow Problems". SIAM Journal on Scientific Computing 44, n.º 3 (junho de 2022): A1775—A1806. http://dx.doi.org/10.1137/21m1440293.

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Borg, Matthew K., e Jason M. Reese. "Multiscale simulation of enhanced water flow in nanotubes". MRS Bulletin 42, n.º 04 (abril de 2017): 294–99. http://dx.doi.org/10.1557/mrs.2017.59.

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Yanguas-Gil, A., J. A. Libera e J. W. Elam. "Multiscale Simulations of ALD in Cross Flow Reactors". ECS Transactions 64, n.º 9 (13 de agosto de 2014): 63–71. http://dx.doi.org/10.1149/06409.0063ecst.

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Marquering, H. A., P. van Ooij, G. J. Streekstra, J. J. Schneiders, C. B. Majoie, E. vanBavel e A. J. Nederveen. "Multiscale Flow Patterns Within an Intracranial Aneurysm Phantom". IEEE Transactions on Biomedical Engineering 58, n.º 12 (dezembro de 2011): 3447–50. http://dx.doi.org/10.1109/tbme.2011.2163070.

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Perdikaris, Paris, Leopold Grinberg e George Em Karniadakis. "Multiscale modeling and simulation of brain blood flow". Physics of Fluids 28, n.º 2 (fevereiro de 2016): 021304. http://dx.doi.org/10.1063/1.4941315.

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Skolud, Bozena, Damian Krenczyk e Reggie Davidrajuh. "Multi-assortment production flow synchronization. Multiscale modelling approach". MATEC Web of Conferences 112 (2017): 05003. http://dx.doi.org/10.1051/matecconf/201711205003.

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Luo, Lingai, e Daniel Tondeur. "Multiscale optimization of flow distribution by constructal approach". China Particuology 3, n.º 6 (dezembro de 2005): 329–36. http://dx.doi.org/10.1016/s1672-2515(07)60211-5.

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Žun, I. "Phase discrimination vs. multiscale characteristics in bubbly flow". Experimental Thermal and Fluid Science 26, n.º 2-4 (junho de 2002): 361–74. http://dx.doi.org/10.1016/s0894-1777(02)00148-6.

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Khayrat, Karim, Robert Epp e Patrick Jenny. "Approximate multiscale flow solver for unstructured pore networks". Journal of Computational Physics 372 (novembro de 2018): 62–79. http://dx.doi.org/10.1016/j.jcp.2018.05.043.

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Alessandrini, M., O. Bernard, A. Basarab e H. Liebgott. "Multiscale optical flow computation from the monogenic signal". IRBM 34, n.º 1 (fevereiro de 2013): 33–37. http://dx.doi.org/10.1016/j.irbm.2012.12.015.

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Rebholz, Leo G. "A multiscale V–P discretization for flow problems". Applied Mathematics and Computation 177, n.º 1 (junho de 2006): 24–35. http://dx.doi.org/10.1016/j.amc.2005.10.030.

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LUO, K. H., J. XIA e E. MONACO. "MULTISCALE MODELING OF MULTIPHASE FLOW WITH COMPLEX INTERACTIONS". Journal of Multiscale Modelling 01, n.º 01 (janeiro de 2009): 125–56. http://dx.doi.org/10.1142/s1756973709000074.

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This paper presents a variety of modeling and simulation methods for complex multiphase flow at microscopic, mesoscopic and macroscopic scales. Each method is discussed in terms of its scale-resolving capability and its relationship with other approaches. Examples of application are provided using a liquid–gas system, in which complex multiscale interactions exist among flow, turbulence, combustion and droplet dynamics. Large eddy simulation (LES) is employed to study the effects of a very large number of droplets on turbulent combustion in two configurations in a fixed laboratory frame. Direct numerical simulation (DNS) in a moving frame is then deployed to reveal detailed dynamic interactions between droplets and reaction zones. In both the LES and the DNS, evaporating droplets are modeled in a Lagrangian macroscopic approach, and have two-way couplings with the carrier gas phase. Finally, droplet collisions are studied using a multiple-relaxation-time lattice Boltzmann method (LBM). The LBM treats multiphase flow with real-fluid equations of state, which are stable and can cope with high density ratios. Examples of successful simulations of droplet coalescence and off-center separation are given. The paper ends with a summary of results and a discussion on hybrid multiscale approaches.

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