CSE Symposium Keynote
Accurate, Stable, and Scalable Algorithms for Convection-Dominated Flows
Tuesday, April 10, 2007, 3:00 P.M.
2240 DCL, 1304 W. Springfield Ave., Urbana, IL
Abstract
Accuracy and stability have long been essential pillars of numerical
algorithms for the simulation of fluid flow. With the advent of tera-
and petascale parallel computers comprising thousands or hundreds of
thousands of processors, scalability is emerging as another essential
pillar. To first order, scalability implies that the solution time be
only weakly dependent on the number of processors P, with n/P fixed,
where n is the number of degrees of freedom in the problem.
Time-dependent transport problems having minimal dissipation, such as
electromagnetics and convection-dominated flow, face an additional
scalability challenge, namely, that dispersion errors accumulated at
small scales may become dominant when propagated through the large
domains that are afforded by petaflops computers.
This talk will cover several critical developments that make it
possible to use spectral element simulations in large-scale
convection-dominated incompressible flow simulations on tens of
thousands of processors. Discretization advances that have made the
SEM viable for these problems include stabilizing filters and spectral
element dealiasing. Solver advances include spectral element multigrid
methods that employ robust Schwarz-based smoothers and scalable
parallel coarse-grid solvers. In addition to these fundamental
elements, we touch upon a few technical details that were required to
exceed processor counts in excess of 10,000. We present the results of
several spectral element simulations, including turbulent vascular
flows, heat transfer in reactor core subchannels, and MHD results
computed using > 100 million grid points on 32000 processors of IBM's
Blue Gene Watson platform.
Biography
Dr. Paul Fischer is a computational scientist in the Mathematics and
Computer Science Division of Argonne National Laboratory. He received
his M.S. in mechanical engineering at Stanford and Ph.D at MIT. Before
joining Argonne, he was on the applied mathematics faculty at Brown
University. He has a long-standing interest in advanced scientific
computing applied to flow simulation. He was co-author of the first
three-dimensional spectral element code for computational fluid
dynamics, which was also one of the first software products for
distributed memory parallel computers. His current work is focused on
development of petascale software for simulation of fluid flow and heat
transfer with applications in vascular flows, ocean currents, reactor
thermal-hydraulics, and astrophysics. He is the author of over 80
articles in computational fluid mechanics and co-author of the book
High-Order Methods for Incompressible Fluid Flows. He was a
recipient of the 1999 Gordon Bell Prize in high performance computing.
Guest speaker co-sponsored by
Student Chapter of SIAM.