Download or read book Solution Adaptive Refinement of Unstructured Meshes for Transonic Flows written by Robert James Walsh and published by . This book was released on 1995 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Zonal Multigrid Solution of Compressible Flow Problems on Unstructured and Adaptive Meshes written by Dimitri J. Mavriplis and published by . This book was released on 1989 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mesh Adaption Strategies for Vortex dominated Flows written by Sean Javad Kamkar and published by Stanford University. This book was released on 2011 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new adaptive mesh refinement strategy that is based on a coupled feature-detection and error-estimation approach is developed. The overall goal is to apply the proper degree of refinement to key vortical features in aircraft and rotorcraft wakes. The refinement paradigm is based on a two-stage process wherein the vortical regions are initially identified for refinement using feature-detection, and then the appropriate resolution is determined by the local solution error. The feature-detection scheme uses a local normalization procedure that allows it to automatically identify regions for refinement with threshold values that are not dependent upon the convective scales of the problem. An error estimator, based on the Richardson Extrapolation method, then supplies the identified features with appropriate levels of refinement. The estimator is shown to be well-behaved for steady-state and time-accurate aerodynamic flows. The above strategy is implemented within the Helios code, which features a dual-mesh paradigm of unstructured grids in the near-body domain, and adaptive Cartesian grids in the off-body domain. A main objective of this work is to control the adaption process so that high fidelity wake resolution is obtained in the off-body domain. The approach is tested on several theoretical and practical vortex-dominated flow-fields in an attempt to resolve wingtip vortices and rotor wakes. Accuracy improvements to rotorcraft performance metrics and increased wake resolution are simultaneously documented.

Download or read book Multigrid Solution Strategies for Adaptive Meshing Problems written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1995 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multigrid Solution of the Euler Equations on Unstructured and Adaptive Meshes written by Dimitri Mavriplis and published by . This book was released on 1987 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adaptive Meshing Techniques for Viscous Flow Calculations on Mixed Element Unstructured Meshes written by D. J. Mavriplis and published by . This book was released on 1997 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adaptive Mesh Refinement Theory and Applications written by Tomasz Plewa and published by Springer Science & Business Media. This book was released on 2005-12-20 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced numerical simulations that use adaptive mesh refinement (AMR) methods have now become routine in engineering and science. Originally developed for computational fluid dynamics applications these methods have propagated to fields as diverse as astrophysics, climate modeling, combustion, biophysics and many others. The underlying physical models and equations used in these disciplines are rather different, yet algorithmic and implementation issues facing practitioners are often remarkably similar. Unfortunately, there has been little effort to review the advances and outstanding issues of adaptive mesh refinement methods across such a variety of fields. This book attempts to bridge this gap. The book presents a collection of papers by experts in the field of AMR who analyze past advances in the field and evaluate the current state of adaptive mesh refinement methods in scientific computing.

Download or read book Adaptive Meshing Techniques for Viscous Flow Calculations on Mixed Element Unstructured Meshes written by Dimitri Mavriplis and published by . This book was released on 1997 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Accurate Multigrid Solution of the Euler Equations on Unstructured and Adaptive Meshes written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1988 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Unstructured Mesh Algorithms for Aerodynamic Calculations written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1992 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of unstructured mesh techniques for solving complex aerodynamic flows is discussed. The principle advantages of unstructured mesh strategies, as they relate to complex geometries, adaptive meshing capabilities, and parallel processing are emphasized. The various aspects required for the efficient and accurate solution of aerodynamic flows are addressed. These include mesh generation, mesh adaptivity, solution algorithms, convergence acceleration and turbulence modeling. Computations of viscous turbulent two-dimensional flows and inviscid three-dimensional flows about complex configurations are demonstrated. Remaining obstacles and directions for future research are also outlined. unstructured; grids; computational; aerodynamics.

Download or read book Solution adaptive Calculation of Unsteady Blade Row Interactions in Transonic Turbomachinery written by Scott M. Richardson and published by . This book was released on 1996 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the development of an implicit, viscous method for the solution of the quasi-three-dimensional flow equations for rotor-stator interaction in transonic turbomachinery. The flow algorithm is described, followed by the implicit time-marching scheme, and the one-equation turbulence model. The algorithm is implemented on an unstructured grid arrangement of locally structured micro-blocks called 'patches.' Solution-dependent adaptation is used to refine the grid in regions containing flow features which require enhanced resolution. An overlapped sliding grid interface is used to transfer flow equation information between the respective blade grids. The resulting computational algorithm has been used to perform a number of validation exercises and has been demonstrated on a modern transonic turbine stage. Where possible, these results are compared with experimental data and show the ability of the method to accurately capture the unsteady flow physics in a robust and computationally efficient manner.

Download or read book Turbulent Flow Calculations Using Unstructured and Adaptive Meshes written by D. J. Mavriplis and published by . This book was released on 1990 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adaptive Mesh Refinement Method for CFD Applications written by Oscar Luis Antepara Zambrano and published by . This book was released on 2019 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this thesis is the development of an adaptive mesh refinement (AMR) algorithm for computational fluid dynamics simulations using hexahedral and tetrahedral meshes. This numerical methodology is applied in the context of large-eddy simulations (LES) of turbulent flows and direct numerical simulations (DNS) of interfacial flows, to bring new numerical research and physical insight. For the fluid dynamics simulations, the governing equations, the spatial discretization on unstructured grids and the numerical schemes for solving Navier-Stokes equations are presented. The equations follow a discretization by conservative finite-volume on collocated meshes. For the turbulent flows formulation, the spatial discretization preserves symmetry properties of the continuous differential operators and the time integration follows a self-adaptive strategy, which has been well tested on unstructured grids. Moreover, LES model consisting of a wall adapting local-eddy-viscosity within a variational multi-scale formulation is used for the applications showed in this thesis. For the two-phase flow formulation, a conservative level-set method is applied for capturing the interface between two fluids and is implemented with a variable density projection scheme to simulate incompressible two-phase flows on unstructured meshes. The AMR algorithm developed in this thesis is based on a quad/octree data structure and keeps a relation of 1:2 between levels of refinement. In the case of tetrahedral meshes, a geometrical criterion is followed to keep the quality metric of the mesh on a reasonable basis. The parallelization strategy consists mainly in the creation of mesh elements in each sub-domain and establishes a unique global identification number, to avoid duplicate elements. Load balance is assured at each AMR iteration to keep the parallel performance of the CFD code. Moreover, a mesh multiplication algorithm (02) is reported to create large meshes, with different kind of mesh elements, but preserving the topology from a coarser original mesh. This thesis focuses on the study of turbulent flows and two-phase flows using an AMR framework. The cases studied for LES of turbulent flows applications are the flow around one and two separated square cylinders, and the flow around a simplified car model. In this context, a physics-based refinement criterion is developed, consisting of the residual velocity calculated from a multi-scale decomposition of the instantaneous velocity. This criteria ensures grid adaptation following the main vortical structures and giving enough mesh resolution on the zones of interest, i.e., flow separation, turbulent wakes, and vortex shedding. The cases studied for the two-phase flows are the DNS of 2D and 3D gravity-driven bubble, with a particular focus on the wobbling regime. A study of rising bubbles in the wobbling regime and the effect of dimensionless numbers on the dynamic behavior of the bubbles are presented. Moreover, the use of tetrahedral AMR is applied for the numerical simulation of gravity-driven bubbles in complex domains. On this topic, the methodology is validated on bubbles rising in cylindrical channels with different topology, where the study of these cases contributed to having new numerical research and physical insight in the development of a rising bubble with wall effects.

Download or read book Zonal Multigrid Solution of Compressible Flow Problems on Unstructured and Adaptive Meshes written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-15 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The simultaneous use of adaptive meshing techniques with a multigrid strategy for solving the 2-D Euler equations in the context of unstructured meshes is studied. To obtain optimal efficiency, methods capable of computing locally improved solutions without recourse to global recalculations are pursued. A method for locally refining an existing unstructured mesh, without regenerating a new global mesh is employed, and the domain is automatically partitioned into refined and unrefined regions. Two multigrid strategies are developed. In the first, time-stepping is performed on a global fine mesh covering the entire domain, and convergence acceleration is achieved through the use of zonal coarse grid accelerator meshes, which lie under the adaptively refined regions of the global fine mesh. Both schemes are shown to produce similar convergence rates to each other, and also with respect to a previously developed global multigrid algorithm, which performs time-stepping throughout the entire domain, on each mesh level. However, the present schemes exhibit higher computational efficiency due to the smaller number of operations on each level. Mavriplis, Dimitri J. Unspecified Center NAS1-18107; NAS1-18605; RTOP 505-90-21-01...

Download or read book A Structured grid Adaptive Mesh Refinement Multigrid Algorithm for Steady state Flows written by Scott Andrew Dudek and published by . This book was released on 1996 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adaptive Meshing Techniques for Viscous Flow Calculations on Mixed Element Unstructured Meshes written by National Aeronautics and Space Administration NASA and published by . This book was released on 2018-10-23 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: An adaptive refinement strategy based on hierarchical element subdivision is formulated and implemented for meshes containing arbitrary mixtures of tetrahendra, hexahendra, prisms and pyramids. Special attention is given to keeping memory overheads as low as possible. This procedure is coupled with an algebraic multigrid flow solver which operates on mixed-element meshes. Inviscid flows as well as viscous flows are computed an adaptively refined tetrahedral, hexahedral, and hybrid meshes. The efficiency of the method is demonstrated by generating an adapted hexahedral mesh containing 3 million vertices on a relatively inexpensive workstation. Mavriplis, D. J. Langley Research Center NAS1-19480; RTOP 505-90-52-01...

Download or read book Adaptive Mesh Generation for Viscous Flows Using Delaunay Triangulation written by Dimitri J. Mavriplis and published by . This book was released on 1988 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: