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Author: Ravi Ghanshyam Patel Publisher: ISBN: Category : Languages : en Pages : 350
Book Description
This dissertation covers four topics relevant for particle-laden flow simulation and modeling. First we perform verification of three techniques for mesoscale simulation of particle-laden flows: the volume filtered Euler-Lagrange method, the two fluid model, and the anisotropic Gaussian method. We verify that statistics from Euler-Lagrange simulations of cluster-induced turbulence (CIT) can be extracted with weak parameter sensitivity. These statistics were also found to match well with CIT simulations using the anisotropic Gaussian method. Next, we use the volume filtered Euler-Lagrange method to perform simulations of homogeneous shear cluster-induced turbulence (HSCIT). We find the evolution of HSCIT to be strongly dependent on the relative orientation of shear and gravity. Third, we provide a 3-D extension to the conditional hyperbolic method of moments (CHyQMOM) for mesoscale particle-laden flows. CHyQMOM is a high order, hyperbolic closure to the kinetic moment equations. Lastly, we introduce a regression technique combining Fourier pseudospectral numerical methods and neural networks for finding nonlinear spatial operators from data.
Author: Ravi Ghanshyam Patel Publisher: ISBN: Category : Languages : en Pages : 350
Book Description
This dissertation covers four topics relevant for particle-laden flow simulation and modeling. First we perform verification of three techniques for mesoscale simulation of particle-laden flows: the volume filtered Euler-Lagrange method, the two fluid model, and the anisotropic Gaussian method. We verify that statistics from Euler-Lagrange simulations of cluster-induced turbulence (CIT) can be extracted with weak parameter sensitivity. These statistics were also found to match well with CIT simulations using the anisotropic Gaussian method. Next, we use the volume filtered Euler-Lagrange method to perform simulations of homogeneous shear cluster-induced turbulence (HSCIT). We find the evolution of HSCIT to be strongly dependent on the relative orientation of shear and gravity. Third, we provide a 3-D extension to the conditional hyperbolic method of moments (CHyQMOM) for mesoscale particle-laden flows. CHyQMOM is a high order, hyperbolic closure to the kinetic moment equations. Lastly, we introduce a regression technique combining Fourier pseudospectral numerical methods and neural networks for finding nonlinear spatial operators from data.
Author: Guillermo Casas González Publisher: ISBN: Category : Languages : en Pages : 360
Book Description
In this work we study the numerical simulation of particle-laden fluids, with a focus on Newtonian fluids and spherical, rigid particles. We are thus dealing with a multi-phase (more precisely, a multi-component) problem, with two phases: the fluid (continuous phase) and the the particles (disperse phase). Our general strategy consists in using the discrete element method (DEM) to model the particles and the finite element method (FEM) to discretize the Navier-Stokes equations, which model the continuous phase. The interaction model between both phases is (must be) based on a multiscale concept, since the smallest scales resolved of the continuous phase are considered much bigger than the particles. In other words, the resolution of the numerical model for the particles is finer than that used for the fluid. Consequently, whether implicit or explicit, there must be a filtering or averaging operation involved in the interaction between both phases, where the details of their motions smaller than the smallest resolution scale of the fluid are soothed out, since the latter is the coarsest of the two different resolutions considered. The spatial discretization of the continuous phase is performed with the FEM, using equal-order spaces of shape functions for the velocity and for the pressure. It is a well-known fact that this type of combination involves the violation of the Ladyzenskaja-Babuška-Brezzi (LBB) condition, resulting in an unstable numerical method. Moreover, the presence of the convective term in Eulerian description of the flow also leads to numerical instabilities. Both effects are treated with the sub-grid scale stabilization methods here. About the disperse phase, the trajectory of each particle is calculated based both on the fluid-interaction forces and on the contact forces between them and the surrounding rigid boundaries. The differential equation that describes the motion of particles in between successive collisions, given the mean (averaged) far field and for particles much smaller than the smallest scales of the flow (the Kolmogorov scale in turbulence) is the Maxey-Riley equation (MRE). This equation is the subject of chapter 2. The objective of this theoretical study is to establish quantitative (up to order-of-magnitude accuracy) limits to its range of validity and to the relative importance of its various terms. The method employed is dimensional analysis, which is systematically applied to derive the 'first effects' of a series of phenomena that are neglected in the derivation of the MRE. Chapter 3 is dedicated to the numerical resolution of the MRE. Here we present improvements to the method of van Hinsberg et al. (2011) for the calculation of the history term and analyse the method thoroughly. We include several tests to show the efficiency and utility of the proposed approach. The MRE is directly applicable to flows where the particle-based Reynolds number is Re “ 1. But its relevance reaches further, as its structure is the basis for the majority of extensions that model the movement of suspended particles outside the range of validity of the MRE. Chapter 4 is markedly more applied than the two preceding ones. It treats various industrial flux types with particles where we employ several extensions of the MRE of the type mentioned above. In the first part of this chapter we review the most important of these extensions and study the process of derivative recovery, necessary to calculate several terms in the equation of motion. The tests examples considered include bubble trapping in 'T'-junction tubes, the simulation of drilling systems of the oil industry based on the bombardment of steel particles and fluidized beds. For the latter we use a discrete filtering-based coupling approach, that mirrors the continuous theory sketched above. This set of three chapters (2, 3, 4) is the core of the Thesis, which is completed with an introduction (chapter 1) and the conclusions (chapter 5).
Author: David Schellander Publisher: GRIN Verlag ISBN: 3656501920 Category : Technology & Engineering Languages : en Pages : 155
Book Description
Doctoral Thesis / Dissertation from the year 2013 in the subject Engineering - Mechanical Engineering, grade: 1, University of Linz (Department on Particulate Flow Modelling), language: English, abstract: The numerical hybrid model EUgran+, which is an Eulerian-Eulerian granular phase model extended with models from the Eulerian-Lagrangian model for dense rapid particulate flows, is modified to account for poly-dispersed particle diameter distributions. These modifications include the implementation of I) a new poly-dispersed drag law and of II) new particle boundary conditions distinguishing between sliding and non-sliding particle-wall collisions and III) a new implementation of the population balance equation in the agglomeration model using the Eulerian-Lagrangian approach, referred to as Bus-stop model. Further, the applicability of the EUgran+ model is extended to cover dilute to dense poly-disperse particulate flows. Furthermore, this provides an improvement in the numerical simulation of dust separation and the formation of particle strands in industrial scale cyclones. In this PHD thesis, the EUgran+Poly model is validated at 3 specific cases with different mass loadings: I) poly-dispersed particle conveying in a square pipe with a 90 degree bend at low mass loading (L = 0:00206); II) a particle conveying case in a rectangular pipe with a double-loop at high mass loading (L = 1:5); III) in a vertical pipe the implementation of the agglomeration model is validated. To show the applicability of the presented models a simulation of an industrial cyclone in experimental scale is presented. The validation and application shows that considering a poly-disperse Eulerian-Eulerian granular phase improves the accordance of the simulation results with measurements significantly. Finally, the hybrid model is a good compromise for a computational efficient simulation of particulate transport and separation with different mass loading regimes.
Author: Publisher: ISBN: Category : Languages : en Pages : 40
Book Description
Five benchmark problems are developed and simulated with the computational fluid dynamics and discrete element model code MFiX. The benchmark problems span dilute and dense regimes, consider statistically homogeneous and inhomogeneous (both clusters and bubbles) particle concentrations and a range of particle and fluid dynamic computational loads. Several variations of the benchmark problems are also discussed to extend the computational phase space to cover granular (particles only), bidisperse and heat transfer cases. A weak scaling analysis is performed for each benchmark problem and, in most cases, the scalability of the code appears reasonable up to approx. 103 cores. Profiling of the benchmark problems indicate that the most substantial computational time is being spent on particle-particle force calculations, drag force calculations and interpolating between discrete particle and continuum fields. Hardware performance analysis was also carried out showing significant Level 2 cache miss ratios and a rather low degree of vectorization. These results are intended to serve as a baseline for future developments to the code as well as a preliminary indicator of where to best focus performance optimizations.
Author: Shankar Subramaniam Publisher: Academic Press ISBN: 0323901344 Category : Science Languages : en Pages : 588
Book Description
Modelling Approaches and Computational Methods for Particle-laden Turbulent Flows introduces the principal phenomena observed in applications where turbulence in particle-laden flow is encountered while also analyzing the main methods for analyzing numerically. The book takes a practical approach, providing advice on how to select and apply the correct model or tool by drawing on the latest research. Sections provide scales of particle-laden turbulence and the principal analytical frameworks and computational approaches used to simulate particles in turbulent flow. Each chapter opens with a section on fundamental concepts and theory before describing the applications of the modelling approach or numerical method. Featuring explanations of key concepts, definitions, and fundamental physics and equations, as well as recent research advances and detailed simulation methods, this book is the ideal starting point for students new to this subject, as well as an essential reference for experienced researchers. Provides a comprehensive introduction to the phenomena of particle laden turbulent flow Explains a wide range of numerical methods, including Eulerian-Eulerian, Eulerian-Lagrange, and volume-filtered computation Describes a wide range of innovative applications of these models
Author: Publisher: Academic Press ISBN: 0128013540 Category : Technology & Engineering Languages : en Pages : 389
Book Description
Focusing Mesoscales of Multiscale Problems in Chemical Engineering, a volume in the Advances in Chemical Engineering series provides readers with the personal views of recognized authorities who present assessments of the state-of-the-art in the field and help readers develop an understanding of its further evolution. Subjects covered in the book are not limited to the classical chemical engineering disciplines. Contributions connecting chemical engineering to related scientific fields, either providing a fundamental basis or introducing new concepts and tools, are encouraged. This volume aims to create a balance between well developed areas such as process industry, transformation of materials, energy, and environmental issues, and areas where applications of chemical engineering are more recent or emerging. Contains reviews by leading authorities in their respective areas Provides up-to-date reviews of the latest techniques in the modeling of catalytic processes Includes a broad mix of US and European authors, as well as academic/industrial/research institute perspectives Provides discussions on the connections between computation and experimental methods
Author: Ravi Ghanshyam Patel
Author: Ravi Ghanshyam Patel
Author: Daniel Guedes de Oliveira
Author: Guillermo Casas González
Author: David Schellander
Author: Dazhi Guo
Author: 
Author: Kulwinder Singh
Author: Shankar Subramaniam
Author: 
Author: Ying Xu