SPEChpc™ 2021 Benchmark Description

Benchmark Name

528.pot3d (POT3D)

Benchmark Author

Submitted by Ron Caplan <caplanr_at_predsci_dot_com>

Authors listed in alphabetic order:

Benchmark Program General Category

Solar Physics

Benchmark Description

POT3D computes potential field solutions used to approximate the 3D solar coronal magnetic field using observed photospheric magnetic fields as a boundary condition. It is used for numerous studies of coronal structure and dynamics. It is also part of the CORHEL package at NASA's CCMC where it is used to generate WSA solar wind solutions for use in analysis and providing boundary conditions for heliospheric simulations. POT3D uses a preconditioned conjugate gradient sparse matrix solver for the Laplace equation in 3D spherical coordinates. The Laplacian is evaluated using finite differences on a logically-rectangular non-uniform spherical grid. Polar boundary conditions involve small collective operations to compute polar averages.

Input Description

POT3D uses a namelist in an input file called "pot3d.dat" to set all parameters of a run. It also requires an input 2D data set in HDF5 format to use for the lower boundary condition. This file in the tests provided are called "br_input_.h5" where is the specific test name. The code can optionally output the potential solution in HDF5 by setting "phifile" to a filename such as "phi.h5". To refrain from writing the solution, set phifile=''.

Output Description

POT3D outputs the norm of the solved potential, as well as the magnetic energy for each component of the derived magnetic field (as well as the total). These values are printed to the screen and can be used for validation.

If selected, POT3D also writes the potential solution to a 3D HDF5 file called phi.h5. This involves gathering the solution to rank 0, so it is not recommended for large runs. The resulting file can be validated with the provided files through the included DIFFV program.

Programming Language


External Dependencies

HDF5 Library, MPI Library

Runtime Limitations (such as number of ranks)

Size of local grid on each rank must be smaller than the 32-bit integer limit of 2.14 billion points.

Known portability issues

Version and Licensing

Application Version: 2.21-SPEC

License: Apache 2.0 with the following additional notice:

POT3D's development and support requires substantial effort and we therefore request that Predictive Science Inc. should be acknowledged as the creators of POTS3D by any authors who use it (or derivatives thereof) in their published works.


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