When an aircraft goes supersonic, the boundary layer of the “separation bubble” along the aircraft’s surface can be disrupted by the impact of the resulting sonic boom — and if that happens, there are significant performance losses. At Argonne National Laboratory, researchers are using supercomputing to study this shock/boundary-layer interaction (SBLI), hoping to improve the performance of high-speed aircraft.

More specifically, the team — led by researchers from the University of Maryland — investigated how crossflow (flow parallel to the wingspan) affects SBLI with the aim of developing a predictive theory for the physics of SBLI. To do this, they ran direct numerical simulations of SBLI and crossflow, aiming to mimic the conditions that can negatively affect aircraft performance.

To run these simulations, the researchers turned to the Theta supercomputer at the Argonne Leadership Computing Facility (ALCF). Theta, an HPE-built system powered by Intel CPUs, delivers 6.92 Linpack petaflops and ranked 78th on the most recent Top500 list. Theta also has a sister machine, ThetaGPU, that delivers 3.9 peak petaflops. Thanks to a grant from the DOE’s INCITE program, the team was able to use Theta and a Navier-Stokes solver called Hybrid to run their simulations.

“In addition to showing that — keeping all other things equal — adding crossflow will yield a separation bubble almost 50 percent larger than without, our simulations captured the skew of the flow,” said Johan Larsson, research team lead and a mechanical engineer at the University of Maryland, in an interview with Argonne’s Nils Heinonen. “Because of this, our results were able to show that crossflow gives many different flow angles across the separation bubble’s boundary layer.”

“Models able to account for the effects of crossflow would carry important ramifications for a range of applications, including turbomachinery and swept-wing flows, engine inlets and nozzles, and control surfaces,” he continued.

Beyond increasing efficiency, this type of improvement could have serious implications for aircraft safety: SBLI can, in severe cases, lead to a flameout, which happens when the combustion chamber of an aircraft engine stops combusting, and thus stops propelling the aircraft.

To learn more about this research, read the coverage from Argonne’s Nils Heinonen here.

The research discussed in this article was published as “Crossflow effects on shock wave/turbulent boundary layer interactions” in Theoretical and Computational Fluid Dynamics and the American Institute of Aeronautics and Astronautics Journal. The paper was written by Johan Larsson, Vedant Kumar, Nikhil Oberoi, Mario Di Renzo and Sergio Pirozzoli. It can be accessed at this link.