The Institute for Computational Engineering and Sciences (ICES) at The University of Texas at Austin has been selected by the Department of Energy's National Nuclear Security Administration (NNSA) to develop new computer modeling techniques that can provide more reliable predictions of complex systems.
The Center for Predictive Engineering and Computational Sciences (PECOS), a research unit within ICES, will receive $17 million over five years for the project. The university will contribute another $1.7 million to it.
Dr. Robert Moser, professor of Mechanical Engineering and ICES, is the director of PECOS. The lead co-investigators are Dr. J. Tinsley Oden, director of ICES, and Dr. Omar Ghattas, professor in ICES, Mechanical Engineering and the Jackson School of Geosciences.
About a dozen university faculty members from ICES, Mechanical Engineering and Aerospace Engineering are involved. Moser said that the PECOS team will work with partners at NNSA, NASA, Texas AandM University and Florida State University.
Predictive science is the application of verified and validated computational simulations to predict the response of complex systems where routine experimental tests are not feasible. A critical part of predictive science is the quantification of uncertainties. It is important to know how reliable the results of the computer simulations are.
The University of Texas at Austin researchers will focus on the problem of uncertainty quantification as it applies to the re-entry of vehicles from space into Earth's atmosphere.
When a vehicle reenters the atmosphere, it can be at speeds as high as Mach 40 for a return from the moon. This causes the surrounding gas to be heated to temperatures hotter than the surface of the sun. Computational simulations to predict whether the vehicle will survive require modeling the interaction of the complex physical processes that occur at these extreme temperatures, such as thermal radiation, turbulence, thermal degradation of materials, and thermal and chemical non-equilibrium.
Ensuring the validity and quantifying the uncertainty of the models used in predictive simulations of such complex high-energy systems is challenging because of the many models involved and the many sources of uncertainty. This is the challenge that the PECOS center is undertaking.
PECOS scientists along with partners at NNSA and NASA will be developing the computational tools needed to determine the chances that a given vehicle will not survive reentry. Such tools will be valuable to NASA for designing and operating future space vehicles. Predictive simulation is important for reentry vehicles because flight tests are expensive, and the consequences of failure are so dire.
"We're trying to come up with a computer prediction that says not only what the best estimate of the answer is, but what is the level of uncertainty in the answer," Moser said. "We want to be able to say to the decision makers, 'According to this calculation, there's a 5 percent chance of failure if we re-enter in these conditions.' "
Since the 1992 moratorium on underground nuclear testing, the NNSA has used simulation and modeling tools and capabilities to support assessment and certification of the nation's nuclear weapons stockpile. The research results from the PECOS center can be applied across many areas with which the NNSA is concerned, Moser said.