INCITE Update: Turbulence Researchers Find Smooth Sailing at NERSC

There are real advantages in computing at NERSC, and a project led by Professor P. K. Yeung of the Georgia Institute of Technology to study “Fluid Turbulence and Mixing at High Reynolds Number” now wants to take full advantage of those advantages.

The project, one of three selected by DOE’s INCITE program, was initially awarded 1.2 million processor hours at NERSC. The project team was also awarded a similar allocation at an NSF computing center. Because the two grants had different expiration dates, the team planned to do their first calculations on the NSF system, then complete the project at NERSC.

“Unfortunately, our progress at the other center has been affected by some issues concerning system reliability and job scheduling,” Yeung noted. “The recent NERSC announcement about a 50 percent discount on charging for jobs using 512 or more processors has now created a great opportunity for us to perform our 20483 simulation for a decent length entirely using NERSC resources alone.”

The team is conducting a simulation of rotating turbulent flow subject to Coriolis forces in the equation of motion. As a lead-in to full simulations, Yeung has been running a number of jobs at 10243 grid resolution. “While further analyses of the data are to be performed, preliminary results indicate that the major features of the flow are similar to those previously obtained at lower grid resolutions but at a higher Reynolds number, which implies increased relevance to actual turbulent flows in engineering applications,” he reported.

Although turbulence is a phenomenon that has applications in a wide range of natural and human activities, it is not well understood and is extremely difficult to model accurately on supercomputers. With improved modeling capability of fluid turbulence, scientists will gain greater insight into meteorology, astrophysics, oceanography, environmental quality, combustion, and propulsion, among other research areas. Because of the complexity of turbulence, it is difficult for scientists to accurately predict natural phenomena, such as severe storms, and engineering solutions in areas such as aircraft design, internal combustion engines and industrial flows. Improved models could lead to more efficient jet engines and cleaner-running automobiles.

NERSC staff worked with the research group to examine the code, concluding that “it is reasonably efficient and deemed ready for production, although we can always implement minor improvements when available," Yeung said.

The researchers also praised NERSC’s scheduling of INCITE jobs.

“We really appreciate the priority privilege that has been granted to us in job scheduling,” Yeung wrote to NERSC staff. “This has allowed most of our jobs to start relatively quickly compared to what we experience at other sites. We are excited at the prospect of the great opportunities so uniquely available to us.”