Shockwaves play roles in everything from high-speed aircraft to supernovae – and now, supercomputer-powered research from the Texas A&M University and the Texas Advanced Computing Center (TACC) is helping to shed light on critical shockwave interactions.
“We proposed a number of new ways in which shock turbulence interactions can be understood,” said Diego Donzis, an associate professor at Texas A&M University and co-author of the study. The new research proposes that shocks should not be treated as discontinuities, contradicting the established understanding of shock turbulence interactions that can be traced back to the 1950s.
Whereas prior understandings had relied primarily on the shock’s “Mach number” (the ratio of an object’s speed to the speed of sound around it), Donzis and his fellow researchers theorized that that shock turbulence interactions also depended on the “Reynolds number” (a measure of turbulence strength) and the “turbulent Mach number.” But, Donzis said, when they proposed that idea, they didn’t have the necessary data at the necessary resolutions to prove it.
The researchers turned to TACC’s Stampede2 supercomputer, on which they were awarded compute time through XSEDE (the Extreme Science and Engineering Discovery Environment). Stampede2, a Dell EMC system with Intel Xeon Phi CPUs, rates at 10.7 Linpack petaflops and ranked 19th on the June 2019 Top500 list of the world’s most powerful supercomputers.
“On Stampede2, we ran a very large data set of shock turbulence interactions at different conditions, especially at high turbulence intensity levels, with a degree of realism that is beyond what is typically found in the literature in terms of resolution at the small scales,” Donzis said.
“We also looked at the structure of the shock and, through highly resolved simulations, we were able to understand how turbulence creates holes on the shock,” added Chang Hsin Chen, lead author of the paper. “This was only possible due to the computational power provided by Stampede2.”
The researchers also explored “shock jumps” – abrupt changes in pressure and temperature of matter as it moves along a shock. They are hopeful that their research will help to pave the way for material improvements in day-to-day lives.
“Advances in the understanding of shock turbulence interactions could lead to supersonic and hypersonic flight, to make them a reality for people to fly in a few hours from here to Europe; space exploration; and even our understanding of the structure of the observable universe,” said Donzis. “It could help answer, why are we here? More down to Earth, understanding turbulence in compressible flows could lead to great improvements in combustion efficiency, drag reduction and general transportation.”
About the research
The research referenced in this article was published as “Shock-turbulence interactions at high turbulence intensities” in the May 2019 issue of Journal of Fluid Mechanics. It was written by Chang Hsin Chen and Diego A. Donzis.
The original article describing the research was written by Jorge Salazar and can be found on TACC’s website at this link.
Feature image: A new theoretical framework was developed and tested using the Stampede2 supercomputer to understand turbulent jumps of mean thermodynamic quantities, shock structure and amplification factors. Turbulence comes in from the left in this image, hitting the shock, and leaving the domain from the right. This three-dimensional picture shows the structure of enstrophy and colored by local Mach number with the shock at gray. Credit: Chang-Hsin Chen, TAMU.