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Planetary Giant Impacts: Convergence of High-Resolution Simulations using Efficient Spherical Initial Conditions and SWIFT

Kegerreis, JA; Eke, VR; Gonnet, P; Korycansky, DG; Massey, RJ; Schaller, M; Teodoro, LFA

Planetary Giant Impacts: Convergence of High-Resolution Simulations using Efficient Spherical Initial Conditions and SWIFT Thumbnail


Authors

P Gonnet

DG Korycansky

M Schaller

LFA Teodoro



Abstract

We perform simulations of giant impacts onto the young Uranus using smoothed particle hydrodynamics (SPH) with over 100 million particles. This 100–1000 × improvement in particle number reveals that simulations with below 107 particles fail to converge on even bulk properties like the post-impact rotation period, or on the detailed erosion of the atmosphere. Higher resolutions appear to determine these large-scale results reliably, but even 108 particles may not be sufficient to study the detailed composition of the debris – finding that almost an order of magnitude more rock is ejected beyond the Roche radius than with 105 particles. We present two software developments that enable this increase in the feasible number of particles. First, we present an algorithm to place any number of particles in a spherical shell such that they all have an SPH density within 1% of the desired value. Particles in model planets built from these nested shells have a root-mean-squared velocity below 1% of the escape speed, which avoids the need for long precursor simulations to produce relaxed initial conditions. Second, we develop the hydrodynamics code SWIFT for planetary simulations. SWIFT uses task-based parallelism and other modern algorithmic approaches to take full advantage of contemporary supercomputer architectures. Both the particle placement code and SWIFT are publicly released.

Citation

Kegerreis, J., Eke, V., Gonnet, P., Korycansky, D., Massey, R., Schaller, M., & Teodoro, L. (2019). Planetary Giant Impacts: Convergence of High-Resolution Simulations using Efficient Spherical Initial Conditions and SWIFT. Monthly Notices of the Royal Astronomical Society, 487(4), 5029-5040. https://doi.org/10.1093/mnras/stz1606

Journal Article Type Article
Acceptance Date Jun 5, 2019
Online Publication Date Jun 10, 2019
Publication Date Aug 31, 2019
Deposit Date Jun 18, 2019
Publicly Available Date Jun 18, 2019
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 487
Issue 4
Pages 5029-5040
DOI https://doi.org/10.1093/mnras/stz1606

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Copyright Statement
© 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.








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