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Event Type:

Applied Mathematics and Computation Seminar

Date/Time:

Wednesday, April 22, 2009 - 05:00

Location:

GLK 113

Guest Speaker:

Institution:

Idaho National Laboratory

Abstract:

Historically, Semi-Implicit (SI) methods in CFD have been developed to step over stiff wave time scale in a stable fashion for compressible flow (or MHD), or to handle the elliptic constraint in incompressible flow. SI methods generate a reduce set of scalar implicit systems which are inverted on each time step or within each outer iteration. This is typically achieved via some linearization and time splitting. Both of these can produce additional time integration errors for once through methods, or produce convergence issues for methods which iterate within a time step. In this talk, the concept of using SI methods as preconditioners to Jacobian-Free Newton-Krylov (JFNK) methods is developed. This algorithmic approach results in an implicitly balanced method (no linearization or time splitting). We will provide an overview along with results from all-speed compressible flow, geophysical fluid dynamics (GFD) and magnetohydrodynamics (MHD).