Suche
Ergebnisse
-
Two notes on the implementation of wavelet Galerkin boundary element methods
(1997)SAM Research ReportWe report, in two notes, recent progress in the implementation of wavelet-based Galerkin BEM on polyhedra and study the performance.Report -
An Accuracy Barrier for Stable Three-Time-Level DifferenceSchemes for Hyperbolic Equations
(1997)SAM Research ReportWe consider three-time-level difference schemes for the linear constant coefficient advection equation $u_t$ = $cu_x$. In 1985 it was conjectured that the varrier to the local order $p$ of schemes which are stable is giben by $p \le $2 min {$R$,$S$}. Here $R$ and $S$ denote the number of downwind and upwind points, respectively, in the difference stencil with respect to the characteristic of the differential equation through the update ...Report -
Regularity of interacting nonspherical Fermi surfaces: the exact self-energy
(1997)FIM's preprintsReport -
Wavelet Galerkin Algorithms for Boundary Integral Equations
(1997)SAM Research ReportThe implementation of a fast, wavelet-based Galerkin discretization of second kind integral equations on piecewise smooth surfaces $\Gamma\subset \R^3$ is described. It allows meshes consisting of triangles as well as quadrilaterals. The algorithm generates a sparse, approximate stiffness matrix with $N=O(N(log N)^2)$ nonvanishing entries in $O(N(\log N)^4)$ operations where N is the number of degrees of freedom on the boundary while ...Report -
-
-
HP90: a general & flexible fortran 90 hp-FE code
(1997)SAM Research ReportA general 2D-$hp$-adaptive Finite Element (FE) implementation inFortran 90 is described. The implementation is based on an abstractdata structure, which allows to incorporate the full $hp$-adaptivityof triangular and quadrilateral finite elements.The $h$-refinement strategies are based on $h2$-refinement ofquadrilaterals and $h4$-refinement of triangles. For $p$-refinementwe allow the approximation order to vary within any element. The ...Report -
Hierarchic Models for Laminated Plates and Shells
(1997)SAM Research ReportThe definition, essential properties and formulation of hierarchic models for laminated plates and shells are presented. The hierarchic models satisfy three essential requirements: approximability; asymptotic consistency, and optimality of convergence rate. Aspects of implementation are discussed and the performance characteristics are illustrated by examples.Report -
The method of transport for nonlinear systems of hyperbolic conservation laws in several space dimensions
(1997)SAM Research ReportThe idea of the method of transport is introduced by means of non-linear conservation laws. The systems are rewritten in an advection form accounting for the characteristic propagation directions. A straightforward linearization of this advection form leads to a genuinely multi-dimensional method. Approximations using infinitely many or a finite number of propagation directions are shown.Report -
The Method of Transport for mixed hyperbolic-parabolic systems
(1997)SAM Research ReportStarting from a numerical scheme for solving systems of hyperbolic partial differential equations the transition to parabolic equations of the type of advection-diffusion equations needs a different treatment of the viscous part. Since we are using a genuine multi-dimensional scheme also the fact that the diffusion acts in infinitely many directions shall be captured properly. Therefore, to be able to use this scheme we have developed a ...Report