Memorial Meeting For Paul Garabedian: Talk Abstracts
Paul Garabedian Memorial Conference
Saturday, December 4th, 2010
Warren Weaver Hall (251 Mercer Street), room 109
with a reception to follow in the 13th floor lounge
Professor of Mathematics, Emeritus, Courant Institute
Allen H. Boozer
Consistency of integrated computations with constraints
Integrated computational models are often assumed preferable to a separation of information based on its scientific generality. However, innocent appearing mathematical equations can imply constraints that are violated even in integrated computations supposedly based on those equations. An example is magnetic reconnection. Two conditions, Faraday's law from electrodynamics and the requirement that natural systems be robust against small perturbations, give constraints that are violated in standard computations of magnetic reconnection in non-toroidal plasmas. Constraints on the evolution of magnetic fields that follow from these two conditions will be derived. The issue of the consistency of integrated computations with constraints is especially subtle when the computations are based on physical models of widely differing levels of scientific generality as in plasma simulations in which heuristic plasma models are coupled with Maxwell's equations.
Dick and Jane Design a Fusion Reactor
The quest for fusion energy has now been going on for more than half a century. The research has been, and continues to be, dominated by plasma physicists trying to understand how to confine and heat a plasma to thermonuclear conditions. The basic strategy is to first master the plasma science and then transfer this knowledge to the engineering community so they can develop a viable power plant design. In today’s talk I examine this strategy by considering the basic engineering and nuclear physics constraints that apply to a fusion reactor. This examination leads to an essentially complete design of the reactor that remarkably requires virtually no knowledge of plasma physics! Instead, the engineering design makes “demands” on the plasma physics that must be met if the design is going to be viable from an engineering perspective. One can then question whether or not the present strategy overemphasizes the plasma physics at the expense of fusion technology. Perhaps progress in fusion technology would have a comparable or larger payoff than progress in plasma physics in terms of reaching the final goal – a fusion power plant.
Oak Ridge National Laboratory
This talk will give an overview of my work with Paul Garabedian from 1965 to 1976 in the area of transonic flow focusing on the design and analysis of supercritical airfoils and turbine blades.
This work has been used by virtually all airfoil manufacturers for the wing design of modern commercial aircraft.
Fire Research Division
National Institute of Standards and Technology
Computational Fluid Dynamics Modeling of Fire
The Fire Research Division of NIST (formerly the National Bureau of Standards) has developed and maintained a variety of numerical models over the past 40 years that simulate the effect of fires on buildings. In the past decade, a computational fluid dynamics model has been developed to simulate fire scenarios on scales ranging from a centimeters to kilometers. The model software is used by fire protection engineers to investigate a wide variety of scenarios for both design and forensic applications. The talk will present some of the basic assumptions unique to fire and several applications, including the investigation of the collapse of the World Trade Center.
Sandia National Laboratories
CFD approaches for atmospheric global circulation modeling
Paul Garabedian's applied work focused on design: he made remarkable contributions to the design of efficient airfoils for passenger airplanes and the design of complex magnetic coils needed for stellarators. His main tool for this work was computational fluid dynamics. I will discuss some of the computational methods Paul and his collaborators used to model the three-dimensional magnetic confinement of plasmas in stellarators. Stellarators have a toroidal geometry, with two periodic directions and one radial direction, motivating a hybrid spectral/finite difference approach. My thesis work with Paul on these methods has served me well in other fields, such as atmospheric model development. The Earth's atmosphere is also described by two periodic and one radial direction, and a very similar hybrid spectral/finite different approach is the dominant technique used in global atmospheric models. It is used by both U.S. operational global forecast models, the joint European operational model, and several of the climate models participating in the Intergovernmental Panel on Climate Change (IPCC) assessment reports.