CSE Symposium Keynote
TITLE: Dust in the Wind: Challenges for Urban Aerodynamics
DATE: Thursday, April 21, 2005
TIME: 3:00 P.M.
PLACE: 2240 DCL
1304 W. Springfield Ave., Urbana, IL
ABSTRACT
The fluid dynamics of airflow through a city controls the transport and
dispersion of airborne contaminants. This is primarily a problem of
urban aerodynamics rather than of meteorology. The space scales are
short, tens of meters to a few kilometers, so meteorological effects
enter primarily through the aerodynamic boundary conditions. The
average flow, large-scale fluctuations and turbulence are closely
coupled to the building geometry. Buildings create large rooster-tail
wakes; there are systematic fountain flows up the backs of tall
buildings; and dust in the wind also moves perpendicular to or even
against the locally prevailing wind. The fact that surfaces are rough
and have sharp edges somewhat simplifies the aerodynamics but realistic
atmospheric factors also play a role. Requirements for better
prediction accuracy demand time-dependent, three-dimensional CFD
computations that include solar heating and buoyancy, complete
landscape and building geometry specification including foliage,
realistic
Computing urban aerodynamics accurately is a time-dependent,
High-Performance Computing (HPC) problem. On the other hand, using
this technology in the emergency assessment of industrial spills,
transportation accidents, or terrorist attacks has very tight time
requirements that suggest simple approximations that unfortunately
produce inaccurate models. The trade-off has been the need to choose
either a fast model or to live with accurate results. Using new
fluid-dynamic principles, an urban-oriented emergency assessment system
called CT-Analyst has been invented to solve this dilemma. It produces
accurate results for airborne contaminant scenarios nearly instantly.
Designed to predict all airborne contaminants including Chemical,
Biological, and Radiological (CBR) threats, CT-Analyst has unique new
capabilities and gives HPC accuracy while running much faster than
other current alternatives.
This presentation explains how applied aerodynamics enables CT-Analyst
to do this. A relatively few detailed CFD computations for a given
area can be generalized to describe a wide range of wind directions and
speeds, and all likely source locations using a new data structure
called Dispersion Nomografs. We have developed a portable, entirely
graphical software tool that embodies this new, high-resolution
technology and runs on small personal computers. Real-time users do not
have to wait for results because accurate answers are available with
near zero-latency (that is 10 - 20 scenarios per second). Sequences of
individual cases, such as a continuously changed source location or
wind direction scans, can be computed and displayed as
continuous-action movies. Since the underlying nomograf database is
precomputed, qualitatively new real-time functions such as sensor data
fusion, backtracking to an unknown source location, and evacuation
route planning are possible with almost no computing delay.
BIOGRAPHY
Dr. Boris is an internationally recognized expert in developing and
applying advanced computer technology to the solution of large-scale
scientific and engineering problems, having conceived and led
computational and theoretical studies in many areas of fluid dynamics,
many-body dynamics, reactive flow, and plasma physics and developed
many fluid and chemical kinetic models now in current use for
simulating chemically reactive flows, hydrodynamics, solar physics, and
astrophysical and atmospheric fluid dynamics. He is currently
responsible for developing, supervising, and leading the theoretical
and numerical research of the Laboratory for Computational Physics &
Fluid Dynamics, an interdisciplinary group of engineers, numericists,
fluid dynamicists, and reactive flow physicists. His current research
interests include applications of parallel computing to CFD and
reactive flow, development of parallel near-neighbor algorithms for
molecular dynamics, and computational hydrodynamics for naval
applications.