97 research outputs found
Spectral methods for hyperbolic problems
AbstractWe review the current state of Fourier and Chebyshev collocation methods for the solution of hyperbolic problems with an eye to basic questions of accuracy and stability of the numerical approximations. Throughout the discussion we emphasize recent developments in the area such as spectral penalty methods, the use of filters, the resolution of the Gibbs phenomenon, and issues related to the solution of nonlinear conservations laws such as conservation and convergence. We also include a brief discussion on the formulation of multi-domain methods for hyperbolic problems, and conclude with a few examples of the application of pseudospectral/collocation methods for solving nontrivial systems of conservation laws
Nodal Discontinuous Galerkin Methods on Graphics Processors
Discontinuous Galerkin (DG) methods for the numerical solution of partial
differential equations have enjoyed considerable success because they are both
flexible and robust: They allow arbitrary unstructured geometries and easy
control of accuracy without compromising simulation stability. Lately, another
property of DG has been growing in importance: The majority of a DG operator is
applied in an element-local way, with weak penalty-based element-to-element
coupling.
The resulting locality in memory access is one of the factors that enables DG
to run on off-the-shelf, massively parallel graphics processors (GPUs). In
addition, DG's high-order nature lets it require fewer data points per
represented wavelength and hence fewer memory accesses, in exchange for higher
arithmetic intensity. Both of these factors work significantly in favor of a
GPU implementation of DG.
Using a single US$400 Nvidia GTX 280 GPU, we accelerate a solver for
Maxwell's equations on a general 3D unstructured grid by a factor of 40 to 60
relative to a serial computation on a current-generation CPU. In many cases,
our algorithms exhibit full use of the device's available memory bandwidth.
Example computations achieve and surpass 200 gigaflops/s of net
application-level floating point work.
In this article, we describe and derive the techniques used to reach this
level of performance. In addition, we present comprehensive data on the
accuracy and runtime behavior of the method.Comment: 33 pages, 12 figures, 4 table
Computer Algebra meets Finite Elements: an Efficient Implementation for Maxwell's Equations
We consider the numerical discretization of the time-domain Maxwell's
equations with an energy-conserving discontinuous Galerkin finite element
formulation. This particular formulation allows for higher order approximations
of the electric and magnetic field. Special emphasis is placed on an efficient
implementation which is achieved by taking advantage of recurrence properties
and the tensor-product structure of the chosen shape functions. These
recurrences have been derived symbolically with computer algebra methods
reminiscent of the holonomic systems approach.Comment: 16 pages, 1 figure, 1 table; Springer Wien, ISBN 978-3-7091-0793-
On the scaling of entropy viscosity in high order methods
In this work, we outline the entropy viscosity method and discuss how the
choice of scaling influences the size of viscosity for a simple shock problem.
We present examples to illustrate the performance of the entropy viscosity
method under two distinct scalings
Model Reduction for Multiscale Lithium-Ion Battery Simulation
In this contribution we are concerned with efficient model reduction for
multiscale problems arising in lithium-ion battery modeling with spatially
resolved porous electrodes. We present new results on the application of the
reduced basis method to the resulting instationary 3D battery model that
involves strong non-linearities due to Buttler-Volmer kinetics. Empirical
operator interpolation is used to efficiently deal with this issue.
Furthermore, we present the localized reduced basis multiscale method for
parabolic problems applied to a thermal model of batteries with resolved porous
electrodes. Numerical experiments are given that demonstrate the reduction
capabilities of the presented approaches for these real world applications
Comparison of some Reduced Representation Approximations
In the field of numerical approximation, specialists considering highly
complex problems have recently proposed various ways to simplify their
underlying problems. In this field, depending on the problem they were tackling
and the community that are at work, different approaches have been developed
with some success and have even gained some maturity, the applications can now
be applied to information analysis or for numerical simulation of PDE's. At
this point, a crossed analysis and effort for understanding the similarities
and the differences between these approaches that found their starting points
in different backgrounds is of interest. It is the purpose of this paper to
contribute to this effort by comparing some constructive reduced
representations of complex functions. We present here in full details the
Adaptive Cross Approximation (ACA) and the Empirical Interpolation Method (EIM)
together with other approaches that enter in the same category
Reduced-order semi-implicit schemes for fluid-structure interaction problems
POD-Galerkin reduced-order models (ROMs) for fluid-structure interaction problems (incompressible fluid and thin structure) are proposed in this paper. Both the high-fidelity and reduced-order methods are based on a Chorin-Temam operator-splitting approach. Two different reduced-order methods are proposed, which differ on velocity continuity condition, imposed weakly or strongly, respectively. The resulting ROMs are tested and compared on a representative haemodynamics test case characterized by wave propagation, in order to assess the capabilities of the proposed strategies
- …