National Center for Computational Sciences

NCCS System Models Hummingbird Flight

Phoenix enables researchers to dissect dynamics of nature’s greatest aviator

Despite the progressive nature of science, many phenomena that we experience in our daily lives remain a mystery. Take gravity for example: we know it exists, yet we haven’t the faintest idea how.

Another perhaps less obvious and more tangible example is the hummingbird. This miniature marvel performs aerial feats that today’s fighter pilots can only dream of. Regardless of its prevalence in America’s backyards, little is understood about this creature’s ability to seemingly defy the laws of aerodynamics. By flapping their wings 15 to 80 times per second, depending on the species, hummingbirds can hover and fly backward (no other bird is capable of this), vertically, and laterally. Simply put, hummingbirds are excellent flyers—perhaps the best in the natural world.

"The mechanisms these animals employ to sustain flight do not seem to follow traditional aerodynamic theory and practice," said Andrew Johnson of Digital Rocket Science, who recently used the Phoenix supercomputer at Oak Ridge National Laboratory’s (ORNL’s) National Center for Computational Sciences (NCCS) to model and better understand the hummingbird’s flight. This research has the potential to greatly advance science in the areas of aerodynamics and biology. "These simulations and analysis could not take place without access to the ORNL/NCCS computers," said Johnson.

One potential application of this research is the more efficient design of micro air vehicles, tiny machines that could mimic hummingbirds to provide military and police units with improved surveillance, reconnaissance, and related activities. (Imagine a tiny hummingbird robot, manually controlled by some distant operator, clandestinely whizzing around a battlefield capturing images and video.) Johnson is comparing his hummingbird flight simulations with experimental data gathered from collaborators at Oregon State University (Doug Warrick) and the University of Portland (Bret Tobalske). However, because of the inherent limitations of experimental analysis, said Johnson, simulation is necessary to gain a more thorough understanding of the aerodynamics involved in the hummingbird’s flight.

For example, the collaborators at Oregon State use real hummingbirds in a laboratory wind tunnel, which produces plenty of useful data. However, said Johnson, you cannot tell the hummingbird what to do (in a laboratory) to study it at different angles and configurations; and because the team uses lasers to achieve a cross-sectional picture of air flow around the wings, the resulting images are sometimes limited in showing the full three-dimensional behavior of the flow. With simulation, he said, you can tell the "computational bird" to do just what you want it to, perfect for studying different phenomena, angles, and configurations.

"The results achieved from simulation are more comprehensive," said Johnson, adding that researchers can "plug in different wing types, frequencies, maneuvers, etc." He used approximately 10,000 hours on the NCCS’s Cray X1E Phoenix supercomputer to do just that. The end product: a series of movies that show air pressure on the top and bottom of the hummingbird wing, computed lift-and-drag curves, and animations of cross-section velocity vectors at various locations.

Phoenix is one of the few remaining global address-space vector systems in the world available for research. "The vector system at Oak Ridge National Laboratory is a great resource for the entire community," said Johnson. He further described his experience at the NCCS as "an ideal situation" because of Phoenix’s availability and an "efficient process." Furthermore, he said, all of the necessary documentation was readily available online, and all of his jobs got through quickly. When he did have a small problem, he said, the NCCS staff worked tirelessly to resolve it.

Johnson’s results will be compared with the experimental results obtained by the Oregon team and with further experiments yet to be designed and carried out, possibly bringing researchers one step closer to technologically mimicking hummingbird flight and giving those in security situations a priceless advantage.

ORNL Introduces Supercomputing to Summer Students

NCCS seminar explains basics

The NCCS recently hosted a "Supercomputing Crash Course" to familiarize summer students with the science of high-performance computing.

Approximately 60 students and faculty members attended two workshops, hosted by NCCS staff members Arnold Tharrington and Rebecca Hartmann-Baker. The workshops aimed both to educate the summer students already involved in computational science and to gauge the interests of students who are new to supercomputing.

An overview of the UNIX operating system was a major theme of the workshops, as they were aimed at students with little to no UNIX experience. The instructors also briefly discussed MPI, demonstrating simple MPI programs on the NCCS’s 263-teraflop Jaguar supercomputer, one of the world’s premier high-performance computing systems.

"The main objective [of the MPI workshop] was to get the students to understand the MPI programming model," said Tharrington. "It was a great experience for both the students and the instructors," added Hartmann-Baker. "I look forward to conducting similar workshops in the future."

NCCS Launches New File Management System

Spider up and crawling

NCCS users will find it easier to manage the data files from their calculations with the advent of a new center-wide shared file system that saves all files to one location.

"Spider" (as it has been named) will replace multiple islands of file systems in various locations on the NCCS network with a single scalable system that eventually will serve all the NCCS systems and will connect to the InfiniBand and Ethernet internal networks. Because all simulation data will eventually reside on Spider, users will not need to transfer files among multiple computers and data management systems.

By the end of 2008, Spider will have been expanded to support the petaflop computer, which will use the new file management system exclusively and will have no local scratch files. At that point, Spider will provide 10 PB of storage space and over 200 GB per second of bandwidth and will be mounted on all major NCCS systems.

Deployment of Spider will be a welcome development for researchers. Having a single repository of simulation data will increase their productivity, allowing more time to pursue research goals. By simplifying the use of the data analysis and visualization tools, it may encourage more researchers to take advantage of them and thus increase the value of their data.