Papers & Reports 2006

High fidelity computations were carried out to analyze the orbiter LH2 feedline flowliner. Computations were performed on the Columbia platform which is a 10,240-processor supercluster consisting of 20 Altix nodes with 512 processors each. Various computational models were used to characterize the unsteady flow features in the turbopump, including the orbiter Low-Pressure-Fuel-Turbopump (LPFTP) inducer, the orbiter manifold and an experimental test article used to represent the manifold.
High Fidelity Simulations of Unsteady Flow Through Turbopumps and Flowliners,NAS Technical Report, NAS-06-001, February 2006.

A measurement on a quantum system is said to cause the “collapse” of the quantum state vector or density matrix. An analogous collapse occurs with measurements on a classical stochastic process. This paper addresses the question of describing the response of a classical stochastic process when there is feedback from the output of a measurement to the input, and is intended to give a simplified model for quantum-mechanical processes that occur along a space-like reaction coordinate.
Bidirectional Classical Stochastic Processes with Measurements and Feedback,NAS Technical Report, NAS-06-002, January 2006.

Adaptive mesh refinement (AMR) is a powerful technique that reduces the resources necessary to solve otherwise intractable problems in computational science. The AMR strategy solves the problem on a relatively coarse grid, and dynamically refines it in regions requiring higher resolution
Performance Characteristics of an Adaptive Mesh Refinement Calculation on Scalar and Vector Platforms,NAS Technical Report, NAS-06-003, May 2006.

The NASA Columbia supercomputer was ranked second on the TOP500 List in November, 2004. Such a quantum jump in computing power provides unprecedented opportunities to conduct ultra-high resolution simulations with the finite-volume General Circulation Model (fvGCM).
The 0.125 Degree Finite-Volume General Circulation Model on the NASA Columbia Supercomputer: Preliminary Simulations of Mesoscale Vortices,NAS Technical Report, NAS-06-004, June 2006.

A study is performed to ascertain the validity of the use of inviscid and viscous simulation methods to predict the axial and normal forces during a launch abort scenario for manned space flight vehicles. The proximity drag character of the Apollo launch escape vehicle (LEV) was studied in detail in a wind tunnel during the Apollo program.
Capsule Abort Recontact Simulation,NAS Technical Report, NAS-06-005, June 2006.

This work considers the discontinuous Galerkin (DG) finite element discretization of first-order systems of conservation laws derivable as moments of the kinetic Boltzmann equation with Levermore (1996) closure. Using standard energy analysis techniques, a new class of energy stable numerical flux functions are devised for the DG discretization of Boltzmann moment systems.
On Discontinuous Galerkin Approximations of Boltzmann Moment Systems With Levermore Closure,NAS Technical Report, NAS-06-006, July 2006.

We present a new approach for the computation of shape sensitivities using the discrete adjoint and flow-sensitivity methods on Cartesian meshes with general polyhedral cells (cutcells) at the wall boundaries. By directly linearizing the cut-cell geometric constructors of the mesh generator, an efficient and robust computation of shape sensitivities is achieved.
Aerodynamic Shape Optimization Using a Cartesian Adjoint Method and CAD Geometry,NAS Technical Report, NAS-06-007, July 2006.

Many large-scale parallel scientific and engineering applications, especially climate modeling, often run for lengthy periods and require data checkpointing periodically to save the state of the computation for a program restart. In addition, such applications need to write data to disks for post-processing, e.g., visualization.
A Scalability Study of SGI Clustered XFS Using HDF Based AMR Application,NAS Technical Report, NAS-06-008, July 2006.

As part of the database for building up a biochemical model of DNA radiation damage, electron impact ionization cross sections of sugar-phosphate backbone and DNA bases have been calculated using the improved binary-encounter dipole (iBED) model.
Molecular Data for a Biochemical Model of DNA Damage: Electron Impact Ionization and Dissociative Ionization Cross Sections of DNA Bases and Sugar-Phosphate Backbone,NAS Technical Report, NAS-06-009, August 2006.

The HPC Challenge (HPCC) benchmark suite and the Intel MPI Benchmark (IMB) are used to compare and evaluate the combined performance of processor, memory subsystem and interconnect fabric of five leading supercomputers - SGI Altix BX2, Cray X1, Cray Opteron Cluster, Dell Xeon cluster, and NEC SX-8. These five systems use five different networks (SGI NUMALINK4, Cray network, Myrinet, InfiniBand, and NEC IXS).
Performance Evaluation of Supercomputers using HPCC and IMB Benchmarks,NAS Technical Report, NAS-06-010, August 2006.

The Columbia system at the NASA Advanced Supercomputing (NAS) facility is a cluster of 20 SGI Altix nodes, each with 512 Itanium 2 processors and 1 terabyte (TB) of shared-access memory. Four of the nodes are organized as a 2048-processor capability-computing platform connected by two low-latency interconnects—NUMALink4 (NL4) and InfiniBand (IB).
A Scalability Study of Columbia using the NAS Parallel Benchmarks,NAS Technical Report, NAS-06-011, August 2006.

We study the performance of inter-process communication on four high-speed multiprocessor systems using a set of communication benchmarks. The goal is to identify certain limiting factors and bottlenecks with the interconnect of these systems as well as to compare these interconnects.
Interconnect Performance Evaluation of SGI Altix 3700 BX2, Cray X1, Cray Opteron Cluster, and Dell PowerEdge,NAS Technical Report, NAS-06-012, August 2006.

It is known that General Circulation Models (GCMs) have insufficient resolution to accurately simulate hurricane near-eye structure and intensity. The increasing capabilities of high-end computers have changed this. The mesoscaleresolving finite-volume GCM (fvGCM) has been experimentally deployed on the NASA Columbia supercomputer, and its performance is evaluated in this study by choosing hurricane Katrina as an example.
Hurricane forecasts with a global mesoscale-resolving model: Preliminary results with Hurricane Katrina (2005),Geophysical Research Letters, vol. 33, NAS Technical Report, NAS-06-013, July 2006.
Supplemental Material

The NASA Space Communications Architecture Working Group (SCAWG) has recently been developing an integrated agency-wide space communications architecture in order to provide the necessary communication and navigation capabilities to support NASA’s new Exploration and Science Programs.
The NASA Space Communications Data Networking Architecture,NAS Technical Report, NAS-06-014, August 2006.

A numerical approach is described that simplifies and automates the CFD solution process so that Earth scientists can utilize high-resolution NavierStokes flow solvers as a research tool to investigate wind events on the Earth’s surface.
Navier-Stokes Simulation of Local Winds Over the Earth's Topography,NAS Technical Report, NAS-06-015, September 2006.

High-end computing (HEC) has always played a major role in meeting the modeling and simulation needs of various NASA missions. Two years ago, NASA was on the verge of dramatically enhancing its HEC capability and capacity by significantly increasing its computational and storage resources.
Role of High-End Computing in Meeting NASA's Science and Engineering Challenges,NAS Technical Report, NAS-06-016, September 2006.

The HPC Challenge (HPCC) benchmark suite and the Intel MPI Benchmark (IMB) are used to compare and evaluate the combined performance of processor, memory subsystem and interconnect fabric of six leading supercomputers - SGI Altix BX2, Cray X1, Cray Opteron Cluster, Dell Xeon cluster, NEC SX-8, Cray XT3 and IBM Blue Gene/L. These six systems use also six different networks (SGI NUMALINK4, Cray network, Myrinet, InfiniBand, NEC IXS and IBM Blue Gen/L Torus). T
Performance Comparison of Cray X1 and Cray Opteron Cluster with Other Leading Platforms using HPCC and IMB Benchmarks,NAS Technical Report, NAS-06-017, September 2006.

The mathematical framework for a-posteriori error estimation of functionals elucidated by Eriksson et al. and Becker and Rannacher is revisited in a space-time context. Using these theories, a hierarchy of exact and approximate error representation formulas are presented for use in error estimation and mesh adaptivity.
Space-Time Error Representation and Estimation in Navier-Stokes Calculations,Lecture Notes in Computational Science and Engineering, vol. 56, NAS Technical Report, NAS-06-018, December 2006.

This paper describes four case studies of application performance enhancements on the Columbia supercomputer. The Columbia supercomputer is a cluster of twenty SGI Altix systems, each with 512 Itanium 2 processors and 1 terabyte of global shared-memory, and is located at the NASA Advanced Supercomputing (NAS) facility in Moffett Field.
Columbia Application Performance Tuning Case Studies,Lecture Notes in Computational Science and Engineering, vol. 56, NAS Technical Report, NAS-06-019, December 2006.