Seminars & Events
Mathematics and Computer Science Division Seminar
"Advances in Wave Propagation with the Discontinuous Galerkin Method"
DATE: November 8, 2007
TIME: 10:30 am
SPEAKER: Tim Warburton, Professor, Rice University
LOCATION: Building 221 Conference Room A216, Argonne Natinal Laboratory
Description:
A range of important features relating to the practical application of discontinuous Galerkin (DG) method for wave propagation will be discussed.
Recent investigations of the spectral properties of the discrete discontinuous Galerkin operators have revealed important connections with their continuous Galerkin counter parts. Theoretical and numerical results will be shown which demonstrate the correct asymptotic behavior of these methods and controls spurious solutions under mild assumptions.
Given the suitability of DG for solving Maxwell's equations and their ability to propagate waves over long distance, it is natural to seek effective boundary treatments for artificial radiation boundary conditions. A new family of far field boundary conditions will be introduced which gracefully transmit propagating and evanescent components out of the domain. These conditions are specifically formulated with DG discretizations in mind, however they are also relevant for a range of numerical methods.
There is an Achilles heel to high order discontinuous Galerkin methods when applied to conservation laws. The methods are typically constructed with polynomial field representations and unfortunately these suffer from excess maximum gradients near the edges of elements. I will describe a simple filtering process that allows us to reduce these anomalous gradients and provably yield a dramatic increase in the maximum allowable time step.
Finally, I will discuss progress in using a posteriori error estimates for mesh adaptivity and demonstrate guaranteed error reduction on refinement for some model (static) problems. These results indicate a need for very fine local refinement of meshes to accurately capture solution singularities. I will show a very simple approach for local time stepping with discontinuous Galerkin methods in order to practically use such meshes in time-domain computations.
More Information:
Visitors from outside Argonne National Laboratory need gate clearance to enter the site.
Please call the Mathematics and Computer Science Division at 630-252-7162.
Non-U.S. citizens need to allow 7 days for gate pass clearance approval.
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