Download or read book Towards High Order Compact Discretization of Unsteady Navier Stokes Equations for Incompressible Flows on Unstructured Grids written by Hashim Ibrahim Mohamed Elzaabalawy and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A high-order energy-stable method for solving the incompressible Navier-Stokes equations based on hybrid discontinuous Galerkin method is presented for which the mass and momentum are conserved. The formulation computes exactly pointwise divergence-free velocity fields for standard element types without post-processing operators nor using textit{H}(div)-conforming spaces. This is achieved by proposing a simple and novel definition to the functional space of the pressure, such that it contains the divergence of the approximate velocity. Specific focus is given on applying this method on different element shapes by introducing the concept of reduced-order elements for all standard shapes in 2D and 3D. Further, the incompressibility constraint is handled via the static condensation to solve the saddle point problem. Furthermore, with the aim to simulate high Reynolds numbers flows, the significance of the diffusion stabilization in the hybridizable discontinuous Galerkin framework is analyzed. Referring to literature, the diffusion stabilization term is directly proportional to the diffusivity or the viscosity for the Navier-Stokes equations. In this work, a new expression for the diffusion stabilization term is mathematically derived, where the term is inversely proportional to the diffusivity or viscosity. Its importance for convection dominated flows is emphasized and supported by numerical examples.Moreover, the proposed formulation for the incompressible Navier-Stokes is extended to solve the RANSE for the TNT, BSL, and SST k- omega models for Reynolds numbers up to 10^9.Solving RANSE is a resilient task for high-order methods, due to the non-smooth profiles of the turbulence quantities. In the discontinuous Galerkin framework, the polynomial approximation for these quantities leads to large oscillations that obstruct the non-linear solver. Taking into account the complexity with high-order methods and the fairly large modeling errors of the RANS modeling, low-order methods are believed to be more pragmatic. However, it is illustrated that solving RANSE with high-order methods leads to significantly smaller error magnitudes compared with second-order finite volume based solvers. Additionally, there is a remarkable improvement regarding the number of iterations to obtain a converged solution. Attention is given to the treatment of the specific rate of turbulence dissipation omega in the high-order framework. The possibilities and limitations of simulating industrial incompressible flows using discontinuous Galerkin based methods are assessed in order to draw some general conclusions for industrial applications.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1989 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 A Numerical Resolution Study of High Order Essentially Non oscillatory Schemes Applied to Incompressible Flow written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1992 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Genuinely Multi dimensional Upwinding Algorithm for the Navier Stokes Equations on Unstructured Grids Using a Compact Highly parallelizable Spatial Discretization written by George Timothy Tomaich and published by . This book was released on 1995 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Performance Computing in Science and Engineering 10 written by Wolfgang E. Nagel and published by Springer Science & Business Media. This book was released on 2010-12-14 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the state-of-the-art in simulation on supercomputers. Leading researchers present results achieved on systems of the High Performance Computing Center Stuttgart (HLRS) for the year 2010. The reports cover all fields of computational science and engineering, ranging from CFD to computational physics and chemistry to computer science, with a special emphasis on industrially relevant applications. Presenting results for both vector systems and microprocessor-based systems, the book makes it possible to compare the performance levels and usability of various architectures. As HLRS operates the largest NEC SX-8 vector system in the world, this book gives an excellent insight into the potential of vector systems, covering the main methods in high performance computing. Its outstanding results in achieving the highest performance for production codes are of particular interest for both scientists and engineers. The book includes a wealth of color illustrations and tables.
Download or read book Turbulence in River and Maritime Hydraulics written by Michele Mossa and published by MDPI. This book was released on 2019-03-08 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding of the role of turbulence in controlling transport processes is of paramount importance for the preservation and protection of aquatic ecosystems, the minimization of the deleterious consequences of anthropogenic activity, and the successful sustainable development of river and maritime areas. In this context, the present Special Issue collects 15 papers which provide a representation of the present understanding of turbulent processes and their effects in river and maritime environments. The presented collection of papers is not exhaustive, but it highlights the key priority areas and knowledge gaps in this field of research. The published papers present the state-of-the-art knowledge of complex environmental flows which are useful for researchers and practitioners. The paper contents are an overview of some recent topics of research and an exposure of the current and future challenges associated with these topics.
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2007 with total page 990 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Methods in Turbulence Simulation written by Robert Moser and published by Elsevier. This book was released on 2022-11-30 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical Methods in Turbulence Simulation provides detailed specifications of the numerical methods needed to solve important problems in turbulence simulation. Numerical simulation of turbulent fluid flows is challenging because of the range of space and time scales that must be represented. This book provides explanations of the numerical error and stability characteristics of numerical techniques, along with treatments of the additional numerical challenges that arise in large eddy simulations. Chapters are written as tutorials by experts in the field, covering specific both contexts and applications. Three classes of turbulent flow are addressed, including incompressible, compressible and reactive, with a wide range of the best numerical practices covered. A thorough introduction to the numerical methods is provided for those without a background in turbulence, as is everything needed for a thorough understanding of the fundamental equations. The small scales that must be resolved are generally not localized around some distinct small-scale feature, but instead are distributed throughout a volume. These characteristics put particular strain on the numerical methods used to simulate turbulent flows. - Includes a detailed review of the numerical approximation issues that impact the simulation of turbulence - Provides a range of examples of large eddy simulation techniques - Discusses the challenges posed by boundary conditions in turbulence simulation and provides approaches to addressing them
Download or read book Mathematical Reviews written by and published by . This book was released on 2005 with total page 1852 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA SP written by and published by . This book was released on 1992 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aeronautical Engineering written by and published by . This book was released on 1992 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA).
Download or read book Proceedings of the ASME Fluids Engineering Division written by and published by . This book was released on 2003 with total page 866 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Order Numerical Methods for Inviscid and Viscous Flows on Unstructured Grids written by Yuzhi Sun and published by . This book was released on 2004 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An incompressible 3 D Navier Stokes method with adaptive hybrid grids written by Alice Josephine Chen and published by . This book was released on 1995 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt:
