An algorithm that helps engineers design better helicopters
may help astronomers more precisely envision the formation of
planets and galaxies.
Yale researchers Darryl Seligman and Greg Laughlin have created
a new model for understanding how black holes,
planets, and galaxies emerge from the vortex-rich environments
of space. They drew inspiration from a mechanical engineering
algorithm that shows how air flows past a helicopter’s rotor
“Space is full of gas, dust, fluids, and turbulence. We wanted
to do a better job of accounting for the swirling of all this
material,” said Seligman, a graduate student and first author
of the study.
That swirling comes from a vortex—or rather, multiple
vortices—which spin and pull things toward their center. In
particular, Laughlin and Seligman sought to replicate the
interaction of vortices in an accretion disk, which is the rotating field of
matter that surrounds massive cosmic bodies such as black holes. Accretion disks are the breeding
grounds for new planets, solar systems, and galaxies.
Traditional models for planet formations and similar phenomena
have been based on an explosive cosmic environment, full of
strong shocks. Laughlin and Seligman decided to create a new
model, called Maelstrom3D, that focuses on the
interplay of vortices in a less combustible cosmic environment.
Initially, the researchers looked at computer graphics
simulations of explosions as a model. But they eventually
decided such simulations did not contain the required level of
complexity to model the turbulence of space.
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A new study by Darryl Seligman and Greg Laughlin of Yale’s
Department of Astronomy applies algorithms used to model
helicopter rotors to model vortices in space. Credit: Yale
That’s when they came across a decade-old study by a group of
mechanical engineers. The study presented an algorithm for
showing how helicopter rotor blades interacted with vortices they
“When designing a helicopter, it’s literally mission-critical
to get the blade-vortex interaction right,” Laughlin said.
“Darryl has been able to transfer the rigorous aeronautical
modeling framework to simulations of astrophysical
environments, and it’s clear that this makes a major
Using their new model, the researchers applied it to a pair of
vortices inserted into a hypothetical patch of accretion disk.
They found two main differences from previous models: The
vortices may be shedding Rossby waves (atmospheric waves) as
they spin, and the number of orbits between the two vortices,
which is related to the viscosity of the environment, is
different as rendered with their model.
“We were stunned by the level of detail we were able to
achieve,” Seligman said.
The findings appear online in The Astrophysical Journal.
He added that Maelstrom3D might have other applications beyond
astronomy. For example, a recent study suggested that ancient
plesiosaurs generated vortices with their front flippers, which
helped their back flippers generate more energy for propulsion.
“That type of fluid dynamics is very similar to the vortices
generated by blade vortex interactions in a helicopter rotor or
airplane wing, and is exactly the type of phenomenon our code
is designed to handle,” Seligman said.
More information: “A Vorticity-Preserving Hydrodynamical
Scheme for Modeling Accretion Disk Flows,” Darryl Seligman
& Gregory Laughlin, 2017 Oct. 10, Astrophysical
Journal iopscience.iop.org/article/10. …
847/1538-4357/aa8e45 , arxiv.org/abs/1709.07007