Our Planet

Parallel Mesh Adaptation for Unsteady Asteroid Blast Simulations

Adaptive mesh simulations of a hypothetical asteriod airburst
Blast footprints (maximum overpressure on ground throughout time) for a fixed-mesh simulation (left) and the finest adaptation cycle (right) of a hypothetical asteroid with a 50-megaton airburst. Near the blast center, 10-pounds-per-square inch (psi) contours are very similar. However, adaptive meshes carry 4-psi and 2-psi overpressure to farther distances both crossrange and downrange. Wade Spurlock, NASA/Ames

Mesh adaptation—the modification of an existing mesh to accurately capture flow features—is essential for controlling the cost of large-scale, high-resolution simulations. Research scientists at NASA’s Ames Research Center developed an efficient parallel unsteady mesh adaptation approach and applied this method to simulations of a full-scale, 3D asteroid entry with a 50-megaton airburst and blast propagation in a heavy atmosphere. Their approach uses multiple sweeps over the time domain and constructs adapted meshes simultaneously in an embarrassingly parallel fashion in order to avoid the typical bottleneck of sequential adaptation that inhibits scalability. Simulated ground footprints of asteroid blast overpressure describe the hypothetical damage that could be caused by an asteroid of this size and energy. When compared to previous fixed-mesh results, the adaptive mesh approach produces more accurate results using slightly less computational time, with all meshing and adaptation work accounting for less than 2% of the total simulation time.

Quick Facts

Asteroid entry simulations are computationally challenging, as they require large domains but must resolve relatively small and short-duration flow features. This wide range of both spatial and temporal scales leads to immense computational cost and must be approached with massively parallel simulations on supercomputers.

Wade Spurlock,
NASA Ames Research Center
  • Simulations were done using NASA’s Cart3D simulation code on 4,000 Cascade Lake cores on the Aitken supercomputer and took roughly 10 hours to complete.
  • Mesh adaptation can be applied efficiently to unsteady simulations on large parallel systems. Solving on adapted meshes that are tailored to the solution at any point in time increases simulation accuracy for roughly the same or even less computational cost, and significantly reduces total simulation time.
  • While an impact of this magnitude is extremely unlikely, data from these simulations helps quantify the risk associated with planetary impact of large asteroids. It also helps researchers understand what simulation tools are needed for accurate prediction and identifies gaps in existing tools.
  • This work explores a mesh adaptation technique that can increase accuracy and reduce computational cost of unsteady simulations and will be used for future high-fidelity simulations of asteroid entry.

Researchers

  • Wade Spurlock, NASA Ames Research Center
  • Michael Aftosmis, NASA Ames Research Center

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