Large-scale density-driven flow simulations using parallel unstructured Grid adaptation and local multigrid methods

2005 ◽  
Vol 17 (11) ◽  
pp. 1415-1440 ◽  
Author(s):  
Stefan Lang ◽  
Gabriel Wittum
Keyword(s):  
Large Scale ◽  
Unstructured Grid ◽  
Multigrid Methods ◽  
Flow Simulations ◽  
Density Driven Flow ◽  
Grid Adaptation

scholarly journals An Initial Investigation of Adjoint-Based Unstructured Grid Adaptation for Vortical Flow Simulations

2011 ◽  
Vol 2011 ◽  
pp. 1-9
Author(s):  
Li Li
Keyword(s):  
Unstructured Grid ◽  
Delta Wing ◽  
Leading Edge ◽  
Grid Resolution ◽  
Vortical Flow ◽  
Delta Wings ◽  
Flow Simulations ◽  
Grid Adaptation ◽  
Grid Points ◽  
Adaptation Method

A computational fluid dynamics (CFDs) method utilizing unstructured grid technology has been employed to compute vortical flow around a65°delta wing with sharp leading edge, which is specially known as the geometry of the second international vortex flow experiment (VFE-2). In VFE-2,65°delta wings with different leading edges had been broadly investigated by experiments, which resulted in a special database for CFDs codes validation. The emphasis of this paper is to investigate the effectiveness of an adjoint-base grid adaptation method for unstructured grid in capturing concentrated vortices generated at sharp edges or flow separation lines of lifting surfaces flying at high angles of attack. Earlier experiences in vortical flow simulations had indicated that the vortex behavior is highly dependent on the local grid resolution both on body surface and space. The adjoint-based adaptation method used here is hoped to save grid points with a reasonable grid resolution for vortical flow simulations. The basic idea is to construct a new adaptive sensor in a grid adaptation process with the intent to tell where the elements should be smaller or larger by introducing an adjoint formulation to relate the estimated functional error to local residual errors of both the primal and adjoint solutions.

scholarly journals Parallel Anisotropic Unstructured Grid Adaptation

2019 ◽  
Author(s):  
Christos Tsolakis ◽  
Nikos Chrisochoides ◽  
Michael A. Park ◽  
Adrien Loseille ◽  
Todd R. Michal
Keyword(s):  
Unstructured Grid ◽  
Grid Adaptation

Grid adaptation in vortical flow simulations

1997 ◽  
Author(s):  
N. Ceresola ◽  
M. Arthur ◽  
W. Kordulla ◽  
M. Arthur ◽  
W. Kordulla ◽  
...  
Keyword(s):  
Vortical Flow ◽  
Flow Simulations ◽  
Grid Adaptation

scholarly journals Algebraic multigrid methods

Acta Numerica ◽  
2017 ◽  
Vol 26 ◽  
pp. 591-721 ◽  
Author(s):  
Jinchao Xu ◽  
Ludmil Zikatanov
Keyword(s):  
Minimization Problem ◽  
Large Scale ◽  
Multigrid Method ◽  
Approximate Solutions ◽  
Multigrid Methods ◽  
Algebraic Multigrid ◽  
Unified Framework ◽  
Smoothed Aggregation ◽  
Algebraic Multigrid Methods ◽  
Coarse Space

This paper provides an overview of AMG methods for solving large-scale systems of equations, such as those from discretizations of partial differential equations. AMG is often understood as the acronym of ‘algebraic multigrid’, but it can also be understood as ‘abstract multigrid’. Indeed, we demonstrate in this paper how and why an algebraic multigrid method can be better understood at a more abstract level. In the literature, there are many different algebraic multigrid methods that have been developed from different perspectives. In this paper we try to develop a unified framework and theory that can be used to derive and analyse different algebraic multigrid methods in a coherent manner. Given a smoother$R$for a matrix$A$, such as Gauss–Seidel or Jacobi, we prove that the optimal coarse space of dimension$n_{c}$is the span of the eigenvectors corresponding to the first$n_{c}$eigenvectors$\bar{R}A$(with$\bar{R}=R+R^{T}-R^{T}AR$). We also prove that this optimal coarse space can be obtained via a constrained trace-minimization problem for a matrix associated with$\bar{R}A$, and demonstrate that coarse spaces of most existing AMG methods can be viewed as approximate solutions of this trace-minimization problem. Furthermore, we provide a general approach to the construction of quasi-optimal coarse spaces, and we prove that under appropriate assumptions the resulting two-level AMG method for the underlying linear system converges uniformly with respect to the size of the problem, the coefficient variation and the anisotropy. Our theory applies to most existing multigrid methods, including the standard geometric multigrid method, classical AMG, energy-minimization AMG, unsmoothed and smoothed aggregation AMG and spectral AMGe.

scholarly journals Verification of Unstructured Grid Adaptation Components

AIAA Journal ◽  
2020 ◽  
Vol 58 (9) ◽  
pp. 3947-3962
Author(s):  
Marshall C. Galbraith ◽  
Philip C. Caplan ◽  
Hugh A. Carson ◽  
Michael A. Park ◽  
Aravind Balan ◽  
...  
Keyword(s):  
Unstructured Grid ◽  
Grid Adaptation

Compressible Flow Simulations on a Massively Parallel Computer

1991 ◽  
Vol 02 (01) ◽  
pp. 430-436
Author(s):  
ELAINE S. ORAN ◽  
JAY P. BORIS
Keyword(s):  
Compressible Flow ◽  
Chemical Reactions ◽  
Large Scale ◽  
Model Development ◽  
Time Dependent ◽  
Parallel Computer ◽  
Massively Parallel ◽  
Parallel Solution ◽  
Flow Simulations ◽  
Connection Machine

This paper describes model development and computations of multidimensional, highly compressible, time-dependent reacting on a Connection Machine (CM). We briefly discuss computational timings compared to a Cray YMP speed, optimal use of the hardware and software available, treatment of boundary conditions, and parallel solution of terms representing chemical reactions. In addition, we show the practical use of the system for large-scale reacting and nonreacting flows.

Some challenges of realistic flow simulations by unstructured grid CFD

2003 ◽  
Vol 43 (6-7) ◽  
pp. 769-783 ◽  
Author(s):  
Kazuhiro Nakahashi ◽  
Yasushi Ito ◽  
Fumiya Togashi
Keyword(s):  
Unstructured Grid ◽  
Flow Simulations
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