Papers & Reports 2013
Time-Accurate Aeroelastic Computations of a Full Helicopter Model using the Navier-Stokes Equations
A time-accurate procedure to model fluid/structure interactions of helicopter blades is presented. The Navier-Stokes equations in conjunction with the one-equation Spalart-Allmaras turbulence model are used to compute the flow. Structural dynamics is modeled using the modal equations. The aerodynamic and structural dynamic equations are coupled time-accurately using the linear acceleration method of Newmark (direct integration scheme).
Time-Accurate Aeroelastic Computations of a Full Helicopter Model using the Navier-Stokes Equations,International Journal of Aerospace Innovations, Vol. 5, No 3+4, pp. 73-82, December 2013.
An Extension of the Time-Spectral Method to Overset Solvers
A presentation of work developing a robust and consistent method for handling relative motion with the Time-Spectral approach within an overset or Cartesian mesh framework, while still approaching the spectral convergence rate of the non-overset scheme.
An Extension of the Time-Spectral Method to Overset Solvers,AIAA Aerospace Sciences Meeting, Dallas, TX, January 2013.
Output Error Estimates and Mesh Refinement in Aerodynamic Shape Optimization
An investigation of the control of discretization error in gradient-based aerodynamic shape optimization through the use of adaptive mesh refinement. Shape optimization is usually performed on meshes with cell spacing and total mesh size determined a priori. This work adapts the mesh at each design iteration to improve accuracy and reduce optimization setup time by eliminating the need to hand-craft a mesh that is suitable for all design iterations.
Output Error Estimates and Mesh Refinement in Aerodynamic Shape Optimization,AIAA Aerospace Sciences Meeting, Dallas, TX, January 2013.
Visualization and Analysis of Vortex Features in Helicopter Rotor Wakes
This paper addresses the topic of flow visualization for complex, vortex-dominated flow fields, like those associated with rotorcraft in hover and forward flight. Vortex interactions in helicopter rotor wakes are visualized using enhanced flow visualization techniques, including iso-surface clipping and flow texture improvements. These techniques, in turn, play a crucial role in understanding the dynamics of complex flows. The visualization techniques are applied to three computational fluid dynamics simulations of helicopter flow fields, and provide a good depiction of rotor tip vortices in these flows. Winner of the 2014 Shahyar Pirzadeh Memorial Award for Outstanding Paper in Meshing Visualization and Computational Environments. (Full article requires login).
Visualization and Analysis of Vortex Features in Helicopter Rotor Wakes,51st AIAA Aerospace Sciences Meeting, Dallas, TX, January 2013.
Navier-Stokes Based Unsteady Aerodynamic Computations of Launch Vehicles Undergoing Forced Coupled Oscillations
A procedure is presented to accurately model transient motions of launch vehicles associated with complex flow conditions. The flow is modeled using the Reynolds-Averaged Navier-Stokes equations with the one-equation Spalart-Allmaras turbulence model. An overset grid system with a curvilinear near-body grid and a Cartesian off body is used.
Navier-Stokes Based Unsteady Aerodynamic Computations of Launch Vehicles Undergoing Forced Coupled Oscillations,54th AIAA Structures, Structural Dynamics, and Materials Conference, Boston, MA, April 8-11, 2013.
Transparent Optimization of Parallel File System I/O via Standard System Tool Enhancement
Standard system tools employed by users on a daily basis do not take full advantage of parallel file system I/O bandwidth and do not understand associated idiosyncrasies such as Lustre striping. This can lead to non-optimal utilization of both the user's time and system resources. This paper describes a set of modifications made to existing tools that increase parallelism and automatically handle striping.
Transparent Optimization of Parallel File System I/O via Standard System Tool Enhancement,2nd International Workshop on High Performance Data Intensive Computing, Boston, MA, May 24, 2013.
Variations in Atmospheric CO2 Growth Rates Coupled With Tropical Temperature
Previous studies have highlighted the occurrence and intensity of El Nino-Southern Oscillation as important drivers of the interannual variability of the atmospheric CO2 growth rate, but the underlying biogeophysical mechanisms governing such connections remain unclear. This paper shows a strong and persistent coupling between interannual variations of the CO2 growth rate and tropical land-surface air temperature during 1959 to 2011. (Full article requires login).
Variations in Atmospheric CO2 Growth Rates Coupled With Tropical Temperature,Proceedings of the National Academy of Sciences of the United States of America (PNAS), July 24, 2013 (Early Edition).
Dual Level Parallel Computations for Large Scale High-Fidelity Database to Design Aerospace Vehicles
A dual-level parallel procedure is presented for computing large databases to support aerospace vehicle design. This procedure has been developed as a single Unix script within the Parallel Batch Submission environment utilizing MPIexec and runs MPI based analysis software. It has been developed to provide a process for aerospace designers to generate data for large numbers of cases with the highest possible fidelity and reasonable wall clock time.
Dual Level Parallel Computations for Large Scale High-Fidelity Database to Design Aerospace Vehicles,NASA/TM-2013-216602, September 2013.
