Title: Building Blocks for Reliable Complex Nonlinear Numerical Simulations

Speaker: Helen Yee, Exploration Technologies Directorate, NASA Ames Research Center

Date/Time: Wednesday, May 25, 2005, 9:00-10:30 am

Location: Building 980, Room 95 (Sandia NM)

Brief Abstract: This talk describes some of the building blocks to ensure a higher level of confidence in the predictability and reliability (PAR) of numerical simulation of multiscale complex nonlinear problems. The focus is on relating PAR of numerical simulations with complex nonlinear phenomena of numerics.
To isolate sources of numerical uncertainties, the possible discrepancy between the chosen partial differential equation (PDE) model and the real physics and/or experimental data is set aside. The discussion is restricted to how well numerical schemes can mimic the solution behavior of the underlying PDE model for finite time steps and grid spacings. The situation is complicated by the fact that the available theory for the understanding of nonlinear behavior of numerics is not at a stage to fully analyze the nonlinear Euler, Navier-Stokes and MHD equations. The discussion is based on the knowledge gained for nonlinear model problems with known analytical solutions to identify and explain the possible sources and remedies of numerical uncertainties in practical computations. Examples relevant to numerical prediction of flow transition/chaos by direct simulation are included.

CSRI POC: Randall M. Summers, (505) 844-6296