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Cholla-MHD: An Exascale-Capable Magnetohydrodynamic Extension to the Cholla Astrophysical Simulation Code

Caddy, Robert V. (2024) Cholla-MHD: An Exascale-Capable Magnetohydrodynamic Extension to the Cholla Astrophysical Simulation Code. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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We present an extension of the massively parallel, GPU native, astrophysical hydrodynamics code Cholla to magnetohydrodynamics (MHD). Cholla solves the ideal MHD equations in their Eulerian form on a static Cartesian mesh utilizing the Van Leer + Constrained Transport integrator, the HLLD Riemann solver, and reconstruction methods at second and third order. Cholla's MHD module can perform over 200 million cell updates per GPU-second while using the HLLD Riemann solver and second order reconstruction. The inherently parallel nature of GPUs combined with increased memory in new hardware allows Cholla's MHD module to perform simulation with resolutions of $>450^3$ cells on a single GPU. We employ GPU direct MPI to attain nearly perfect weak scaling on the exascale supercomputer \textit{Frontier}, while using up to 74,000 GPUs and simulating a total grid size of over 1.2 trillion cells. A suite of test problems highlights the accuracy of Cholla's MHD module and demonstrates that zero magnetic divergence in solutions is maintained to round off error. We also present new testing and continuous integration tools using GoogleTest, GitHub Actions, and Jenkins that have made development more robust and accurate and ensure reliability in the future.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Caddy, Robert V.r.caddy@pitt.edurvc90000-0002-4475-3181
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairSchneider, Evan E.eschneider@pitt.eduevs340000-0001-9735-7484
Committee MemberBezanson, Rachelrachel.bezanson@pitt.edu0000-0001-5063-8254
Committee MemberBadenes, Carlesbadenes@pitt.edu0000-0003-3494-343X
Committee MemberFreitas, Ayresafreitas@pitt.edu0000-0003-2137-6034
Committee MemberDi Matteo,
Date: 13 May 2024
Date Type: Publication
Defense Date: March 2024
Approval Date: 13 May 2024
Submission Date: 11 January 2024
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 91
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Astronomy
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Magnetohydrodynamics, Magnetohydrodynamical simulations, Galaxy structure, Circumgalactic medium, Astronomical simulations, Astronomy software, Open source software, Publicly available software, Computational methods, Computational astronomy, GPU computing
Date Deposited: 13 May 2024 13:46
Last Modified: 13 May 2024 13:46


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