Download or read book High order Energy Stable Flux Reconstruction Schemes for Fluid Flow Simulations on Unstructured Grids written by Patrice Castonguay and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nowadays, most commercial CFD software relies exclusively on low-order methods (methods for which the spatial order of accuracy is at most two) for the simulation of flows over complex geometries. Although these methods are extremely robust and efficient, they are often inadequate when simulations require a very high level of accuracy. As desired error tolerances continue to decrease, high-order methods for unstructured grids will continue to grow in popularity. In the context of fluid flow simulations, applications that require high levels of accuracy (which could therefore benefit greatly from the use of high-order methods) include Direct Numerical Simulations (DNS), Large-Eddy Simulations (LES), Computational Aero-Acoustics (CAA) and vortex dominated flows. In 2007, Huynh presented the Flux Reconstruction (FR) approach to high-order methods. The method is attractive because it is intuitive, straightforward to implement, unifying (in the sense that it can recover various well known high-order methods), computationally efficient (since it does not require the use of numerical integration), and easily parallelizable. However, there remained questions regarding the stability of FR schemes and their applicability to practical fluid flow problems. In this thesis, a new class of FR schemes is identified, and applied to solve the 3D Navier-Stokes equations on mixed unstructured grids. The new schemes are referred to as Energy Stable Flux Reconstruction (ESFR) schemes. Their implementation in 1D, on triangular and quadrilateral elements in 2D, and on prismatic and hexahedral elements in 3D is discussed. The stability and accuracy properties of ESFR schemes are studied thoroughly. An energy stability proof is used to show the linear stability of the schemes for all orders of accuracy, in 1D and on triangular elements in 2D. Various numerical experiments in the field of fluid dynamics are then used to demonstrate their effectiveness. The implementation of ESFR schemes on Graphics Processing Units (GPUs) is also discussed. Because of their high arithmetic intensity and their element-local nature, the schemes are well suited for new massively parallel hardware architectures such as GPUs. The efficient implementation of ESFR schemes on GPUs results in speedups of at least one order of magnitude relative to traditional high-order methods for unstructured grids running on conventional computer hardware.

Download or read book Energy Stable High order Methods for Simulating Unsteady Viscous Compressible Flows on Unstructured Grids written by David Michael Williams and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High-order methods have the potential to dramatically improve the accuracy and efficiency of flow simulations in the field of computational fluid dynamics (CFD). However, there remain questions regarding the stability and robustness of high-order methods for practical problems on unstructured triangular and tetrahedral grids. In this work, a new class of 'energy stable' high-order methods is identified. This class of schemes (referred to as the 'Energy Stable Flux Reconstruction' class of schemes) is proven to be stable for linear advection-diffusion problems, for all orders of accuracy on unstructured triangular grids in 2D and unstructured tetrahedral grids in 3D. Furthermore, this class of schemes is shown to be capable of recovering the well-known collocation-based nodal discontinuous Galerkin scheme, along with new schemes that possess explicit time-step limits which are (in some cases) more than 2x larger than those of the discontinuous Galerkin scheme. In addition, the stability of the Energy Stable Flux Reconstruction schemes is examined for nonlinear problems, and it is shown that stability depends on the degree of nonlinearity in the flux and on the placement of solution and flux points in each element. In particular, it is shown that choosing the solution and flux point locations to coincide with the locations of quadrature points promotes nonlinear stability by minimizing (or eliminating) nonlinear aliasing errors. A new class of symmetric quadrature points is identified on triangles and tetrahedra for this purpose. Finally, the Energy Stable Flux Reconstruction schemes and the new quadrature points are applied to several nonlinear problems with the aim of assessing how well the schemes perform in practice.

Download or read book High order Methods for Unsteady Flows on Unstructured Dynamic Meshes written by Kui Ou and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive study of discontinuous finite element based high-order methods has been performed in this thesis, addressing a wide range of important issues related to high-order methods. The thesis starts with a detailed discussion of nodal based high-order methods and careful analysis of their stability properties. In particular, the formulations of nodal Discontinuous Galerkin method, Spectral Difference method, and Flux Reconstruction method for the scalar conservation laws are discussed first. The differences and similarities among these high-order schemes are carefully examined and effectively used to establish the linear stability of these methods. Stability proofs of nodal Discontinuous Galerkin method, Spectral Difference method, and Flux Reconstruction method subsequently lead to a new type of energy stable high-order scheme called Energy Stable Flux Reconstruction scheme. The extension of this new scheme from linear advection equation to the diffusion equation is formulated and discussed. The fundamental study of the high-order methods for scalar conservation laws lays the theoretical foundation for the subsequent extension to include conservation laws for fluid dynamics. The formulation of spectral difference method for the Navier-Stokes equations is first discussed. Validation tests to verify the resulting flow solver are presented. The extension of the spectral difference based Navier-Stokes flow solver from static fixed computational mesh to include dynamic moving deforming mesh is discussed next. An efficient mesh deformation algorithm that can handle substantial boundary movement is proposed and examined. The invariance of conservation laws mapping between coordinate systems allows the high-order scheme to be formulated on dynamic deforming meshes without deteriorating the formal order of accuracy of the underlying scheme. Detailed formulation, analysis, and validation results are presented. As a result of mesh deformation, the issue of geometric conservation needs to be addressed. The definition and origin of the geometric conservation law are discussed. The differential form of the geometric conservation law is derived from first principles for both the scalar conservation law and the fluid dynamic conservation laws. Subsequently a geometric conservative high-order scheme is formulated. The significance of geometric conservation on the stability and accuracy of the flow solution is examined. Finally a wide range of interesting fluid dynamic phenomena have been studied using the resulting high-order flow solver based on dynamic unstructured meshes. The representative test cases cover fluid dynamic phenomena ranging from completely laminar flows, to unsteady vortex dominated flows, and to flows exhibiting mixed regions of laminar, transitional, and turbulent structures. Other work that has been completed in this thesis is included in the appendix. In particular, continuous unsteady adjoint equations for advection and Burger's equations have been derived and solved using the high-order methods. The method of mesh deformation is reformulated as an optimization problem and used to achieve adaptive mesh refinement.

Download or read book Nodal Discontinuous Galerkin Methods written by Jan S. Hesthaven and published by Springer Science & Business Media. This book was released on 2007-12-18 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers an introduction to the key ideas, basic analysis, and efficient implementation of discontinuous Galerkin finite element methods (DG-FEM) for the solution of partial differential equations. It covers all key theoretical results, including an overview of relevant results from approximation theory, convergence theory for numerical PDE’s, and orthogonal polynomials. Through embedded Matlab codes, coverage discusses and implements the algorithms for a number of classic systems of PDE’s: Maxwell’s equations, Euler equations, incompressible Navier-Stokes equations, and Poisson- and Helmholtz equations.

Download or read book Runge Kutta Discontinuous Galerkin Methods for Convection dominated Problems written by Bernardo Cockburn and published by . This book was released on 2000 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computational Aerodynamics written by Antony Jameson and published by Cambridge University Press. This book was released on 2022-09-01 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational aerodynamics is a relatively new field in engineering that investigates aircraft flow fields via the simulation of fluid motion and sophisticated numerical algorithms. This book provides an excellent reference to the subject for a wide audience, from graduate students to experienced researchers and professionals in the aerospace engineering field. Opening with the essential elements of computational aerodynamics, the relevant mathematical methods of fluid flow and numerical methods for partial differential equations are presented. Stability theory and shock capturing schemes, and vicious flow and time integration methods are then comprehensively outlined. The final chapters treat more advanced material, including energy stability for nonlinear problems, and higher order methods for unstructured and structured meshes. Presenting over 150 illustrations, including representative calculations on unstructured meshes in color. This book is a rich source of information that will be of interest and importance in this pioneering field.

Download or read book Progress in Hybrid RANS LES Modelling written by Sharath Girimaji and published by Springer. This book was released on 2015-02-20 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the proceedings of the Fifth Symposium on Hybrid RANS-LES Methods, which was held on March 19-21 in College Station, Texas, USA. The different chapters, written by leading experts, reports on the most recent developments in flow physics modelling, and gives a special emphasis to industrially relevant applications of hybrid RANS-LES methods and other turbulence-resolving modelling approaches. The book addresses academic researchers, graduate students, industrial engineers, as well as industrial R&D managers and consultants dealing with turbulence modelling, simulation and measurement, and with multidisciplinary applications of computational fluid dynamics (CFD), such as flow control, aero-acoustics, aero-elasticity and CFD-based multidisciplinary optimization. It discusses in particular advanced hybrid RANS-LES methods. Further topics include wall-modelled Large Eddy Simulation (WMLES) methods, embedded LES, and a comparison of the LES methods with both hybrid RANS-LES and URANS methods. Overall, the book provides readers with a snapshot on the state-of-the-art in CFD and turbulence modelling, with a special focus to hybrid RANS-LES methods and their industrial applications.

Download or read book Handbook of Numerical Methods for Hyperbolic Problems written by Remi Abgrall and published by Elsevier. This book was released on 2016-11-17 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Numerical Methods for Hyperbolic Problems explores the changes that have taken place in the past few decades regarding literature in the design, analysis and application of various numerical algorithms for solving hyperbolic equations. This volume provides concise summaries from experts in different types of algorithms, so that readers can find a variety of algorithms under different situations and readily understand their relative advantages and limitations. - Provides detailed, cutting-edge background explanations of existing algorithms and their analysis - Ideal for readers working on the theoretical aspects of algorithm development and its numerical analysis - Presents a method of different algorithms for specific applications and the relative advantages and limitations of different algorithms for engineers or readers involved in applications - Written by leading subject experts in each field who provide breadth and depth of content coverage

Download or read book High Order Methods for Computational Physics written by Timothy J. Barth and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of high-order accurate numerical discretization techniques for irregular domains and meshes is often cited as one of the remaining chal lenges facing the field of computational fluid dynamics. In structural me chanics, the advantages of high-order finite element approximation are widely recognized. This is especially true when high-order element approximation is combined with element refinement (h-p refinement). In computational fluid dynamics, high-order discretization methods are infrequently used in the com putation of compressible fluid flow. The hyperbolic nature of the governing equations and the presence of solution discontinuities makes high-order ac curacy difficult to achieve. Consequently, second-order accurate methods are still predominately used in industrial applications even though evidence sug gests that high-order methods may offer a way to significantly improve the resolution and accuracy for these calculations. To address this important topic, a special course was jointly organized by the Applied Vehicle Technology Panel of NATO's Research and Technology Organization (RTO), the von Karman Institute for Fluid Dynamics, and the Numerical Aerospace Simulation Division at the NASA Ames Research Cen ter. The NATO RTO sponsored course entitled "Higher Order Discretization Methods in Computational Fluid Dynamics" was held September 14-18,1998 at the von Karman Institute for Fluid Dynamics in Belgium and September 21-25,1998 at the NASA Ames Research Center in the United States.

Download or read book Spectral and High Order Methods for Partial Differential Equations ICOSAHOM 2018 written by Spencer J. Sherwin and published by Springer Nature. This book was released on 2020-08-11 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book features a selection of high-quality papers from the presentations at the International Conference on Spectral and High-Order Methods 2018, offering an overview of the depth and breadth of the activities within this important research area. The carefully reviewed papers provide a snapshot of the state of the art, while the extensive bibliography helps initiate new research directions.

Download or read book TILDA Towards Industrial LES DNS in Aeronautics written by Charles Hirsch and published by Springer Nature. This book was released on 2021-06-28 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers detailed insights into new methods for high-fidelity CFD, and their industrially relevant applications in aeronautics. It reports on the H2020 TILDA project, funded by the European Union in 2015-2018. The respective chapters demonstrate the potential of high-order methods for enabling more accurate predictions of non-linear, unsteady flows, ensuring enhanced reliability in CFD predictions. The book highlights industrially relevant findings and representative test cases on the development of high-order methods for unsteady turbulence simulations on unstructured grids; on the development of the LES/DNS methodology by means of multilevel, adaptive, fractal and similar approaches for applications on unstructured grids; and on leveraging existent large-scale HPC networks to facilitate the industrial applications of LES/DNS in daily practice. Furthermore, the book discusses multidisciplinary applications of high-order methods in the area of aero-acoustics. All in all, it offers timely insights into the application and performance of high-order methods for CFD, and an extensive reference guide for researchers, graduate students, and industrial engineers whose work involves CFD and turbulence modeling.

Download or read book Multigrid Techniques written by Achi Brandt and published by SIAM. This book was released on 2011-01-01 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: This classic text presents the best practices of developing multigrid solvers for large-scale computational problems in science and engineering. By representing a problem at multiple scales and employing suitable interscale interactions, multigrid avoids slowdown due to stiffness and reduces the computational cost of classical algorithms by orders of magnitude. Starting from simple examples, this book guides the reader through practical stages for developing reliable multigrid solvers, methodically supported by accurate performance predictors. The revised edition presents discretization and fast solution of linear and nonlinear partial differential systems; treatment of boundary conditions, global constraints and singularities; grid adaptation, high-order approximations, and system design optimization; applications to fluid dynamics, from simple models to advanced systems; new quantitative performance predictors, a MATLAB sample code, and more. Readers will also gain access to the Multigrid Guide 2.0 Web site, where updates and new developments will be continually posted, including a chapter on Algebraic Multigrid.

Download or read book Higher Order Finite Element Methods written by Pavel Solin and published by CRC Press. This book was released on 2003-07-28 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: The finite element method has always been a mainstay for solving engineering problems numerically. The most recent developments in the field clearly indicate that its future lies in higher-order methods, particularly in higher-order hp-adaptive schemes. These techniques respond well to the increasing complexity of engineering simulations and

Download or read book Towards Improvement of Numerical Accuracy for Unstructured Grid Flow Solver written by Qiuying Zhao and published by . This book was released on 2012 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: An effort to improve the numerical accuracy of a three dimensional unstructured grid finite volume scheme is pursued in the present work. Unstructured grid methods have been widely used in computational fluid dynamics for the convenience of modeling complex geometries in realistic applications. In the present work, improvements towards high order unstructured grid schemes are proposed using high order flux formula for spatial discretizations. The Riemann variables on the left and right sides of the interface are reconstructed using quadratic and quartic polynomials composed of both flow variables and their gradients. The high order flux is then calculated using the concept of MUSCL (Monotone Upstream-centered Schemes for Conservation Laws) approach. In order to maintain the accuracy for the finite volume scheme, an innovative method based on Radial Basis Function interpolation is introduced as a substitution to Gaussian quadrature to achieve the higher order surface integration on mixed element unstructured grids. The proposed high order improvements for unstructured grid schemes have been tested for a wide range of flows from very low Mach number to supersonic speeds. The observed accuracy for the improved schemes is verified using a benchmark case about an inviscid vortex transporting in a free stream flow. In addition, the ability to capture the tip trailing vortex, which is a major challenge in computational fluid dynamics today, is extensively verified on two vortex dominated viscous flows, a fixed NACA0015 wing at a subsonic Mach number and a rotating NACA0012 hovering rotor at a transonic tip speed. The numerical validations are also performed on two realistic industrial applications including a marine propeller P5168 and a Bell Helicopter aircraft 427 main rotor. Computational results indicate that the methods proposed in the present work can significantly improve numerical accuracy in predicting the strong vortical flows in smooth regions, while maintaining the stability of the schemes in discontinuous regions such as shockwaves.

Download or read book Adaptive High order Methods in Computational Fluid Dynamics written by Z. J. Wang and published by World Scientific. This book was released on 2011 with total page 471 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book consists of important contributions by world-renowned experts on adaptive high-order methods in computational fluid dynamics (CFD). It covers several widely used, and still intensively researched methods, including the discontinuous Galerkin, residual distribution, finite volume, differential quadrature, spectral volume, spectral difference, PNPM, and correction procedure via reconstruction methods. The main focus is applications in aerospace engineering, but the book should also be useful in many other engineering disciplines including mechanical, chemical and electrical engineering. Since many of these methods are still evolving, the book will be an excellent reference for researchers and graduate students to gain an understanding of the state of the art and remaining challenges in high-order CFD methods.

Download or read book Computational Fluid Dynamics 2006 written by Herman Deconinck and published by Springer. This book was released on 2016-04-01 with total page 916 pages. Available in PDF, EPUB and Kindle. Book excerpt: ThisbookcontainstheproceedingsoftheFourthInternationalConference onComputationalFluidDynamics(ICCFD4), heldinGent, Belgiumfrom July10through16,2006. TheICCFDconferenceseriesisanoutcomeofthe mergeroftwoimportantstreamsofconferencesinComputationalFluid- namics: InternationalConferenceonNumericalMethodsinFluidDynamics, ICNMFD(since1996)andInternationalSymposiumonComputationalFluid Dynamics, ISCFD(since1985). In1998itwasdecidedtojointhetwoand ICCFD emerged as a biannual meeting, held in Kyoto in 2000, Sydney in 2002, Toronto in 2004 and Gent in 2006. Thus, the ICCFD series became theleadinginternationalconferenceseriesforscientists, mathematiciansand engineersinterestedinthecomputationof?uid?ow. The4theditionoftheconferencehasattracted200participantsfromall overtheworld;270abstractswerereceived, ofwhich135wereselectedina carefulpeerreviewprocessbytheexecutivecommittee(C. H. Bruneau, J. -J. Chattot, D. Kwak, N. Satofuka, D. W. Zingg, E. DickandH. Deconinck)for oralpresentationandafurther21forposterpresentation. Thepaperscontainedintheseproceedingsprovideanexcellentsnapshot of the ?eld of Computational Fluid Dynamics as of 2006. Invited keynote lecturesbyrenownedresearchersareincluded, withcontributionsinthe?eld ofdiscretizationschemes, high-endcomputingandengineeringchallenges, and two-phase?ow. Thesekeynotecontributionsarecomplementedby137regular papersonthemostdiverseaspectsofCFD: -Innovativealgorithmdevelopmentfor?owsimulation, optimisationandc- trol: higher-ordermethods(DG, FV, FEandRDmethods), iterativemethods andmultigrid, solutionadaptivemeshtechniques, errorestimationandc- trol, parallelalgorithms. -Innovativemodelingof?owphysicsintheareaofcompressibleandinc- pressible ?ows: hypersonic and reacting ?ows, two-phase ?ows, turbulence (LES, DES, DNS, andtransition), vortexdynamics, boundarylayerstability, multi-scalephysics, magnetohydrodynamics. Preface VII -advancedapplicationsusingtheabovementionedinnovativetechnology, and multidisciplinaryapplicationsincludingaero-elasticityandaero-acoustics. ThanksareduetooursponsorsNASA, theFWOResearchFoundation FlandersandtheEuropeanUnionthroughtheEUA4XMarieCurieproject. Inparticular, thegenerousgrantfromNASAisakeyfactorinthesuccessof thisconferenceseriesandthepublicationoftheseProceedings. Wealsowouldliketothankthesta?andPhDstudentsofthevonKarman InstituteandtheDepartmentof?ow, heatandcombustionmechanicsofthe University of Gent, for the help they provided toward the success of this conference. Sint-Genesius-Rode, Belgium HermanDeconinck vonKarmanInstituteforFluidDynamics Ghent, Belgium ErikDick GhentUniversity September2006 ConferenceChair Contents PartIInvitedSpeakers Twonewtechniquesforgeneratingexactlyincompressible approximatevelocities BernardoCockburn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 RoleofHigh-EndComputinginMeetingNASA'sScience andEngineeringChallenges RupakBiswas, EugeneL. Tu, WilliamR. VanDalsem. . . . . . . . . . . . . . . . 14 RecentAdvancesofMulti-phaseFlowComputationwiththe AdaptiveSoroban-gridCubicInterpolatedPropagation(CIP) Method TakashiYabe, YouichiOgata, KenjiTakizawa. . . . . . . . . . . . . . . . . . . . . . . 29 PartIISchemes OntheComputationofSteady-StateCompressibleFlows UsingaDGMethod HongLuo, JosephD. Baum, RainaldL]ohner. . . . . . . . . . . . . . . . . . . . . . . . 47 Space-TimeDiscontinuousGalerkinMethodforLarge AmplitudeNonlinearWaterWaves YanXu, JaapJ. W. vanderVegt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 AdiscontinuousGalerkinmethodwi

Download or read book Computational Aerodynamics written by Antony Jameson and published by Cambridge University Press. This book was released on 2022-09 with total page 627 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn the design and analysis of numerical algorithms for aerodynamics. Ideal for graduates, researchers, and professionals in the field.