Speaker
Description
COolfluid COrona uNstrUcTured (COCONUT) [1-10] is a data-driven physics-based model for plasma simulations implemented within the open source COOLFluiD platform (https://github.com/andrealani/COOLFluiD/wiki). The core C++ solver implements a second-order accurate Finite Volume (FV) discretization for arbitrary unstructured grids, is fully parallel through the Message Passing Interface (MPI) also supporting parallel I/O capabilities on 1000s of CPU-cores, and provides efficient implicit time integration schemes already allowing for >20X faster-than-real-time simulations. To this end, the Portable Extensible Toolkit for Scientific Computation (PETSc) library is used for solving the resulting linear system of discretized equations via available GMREs algorithms and parallel preconditioners.
While COCONUT’s baseline version [5][9] solves single-fluid magnetohydrodynamics (MHD) equations, a more advanced multi-fluid/Maxwell model [4] is also under development, in particular to better tackle the collisional and radiative processes in the chromosphere. COCONUT features both a polytropic and a full MHD model [2] including heating source term, thermal conduction and radiation cooling.
All simulations are data-driven, i.e. accepting real (pre-processed) magnetic maps as input at the low solar corona or solar surface from various sources (e.g. ADAPT, HMI, GONG) [8][10], providing the radial component of the magnetic field which is used by a Potential-Field Source Surface (PFSS) solver, based upon COOLFluiD’s implicit FV code, to initialize steady MHD simulations. In time-dependent simulations [11], COCONUT accepts a time series of magnetograms as input with arbitrary cadence and can also propagate flux ropes [6] which are injected directly in its initial field.
COCONUT’s computational domain, which is typically meshed with prismatic cells using a Blender-based tool [3], can extend up to 0.1AU, feeding inputs to inhouse-developed open source heliospheric codes such as EUHFORIA [7] and Icarus [1], or all the way up to 2.5AU, as in the most recent simulation efforts.
This presentation will provide an overview of all the above mentioned features, highlighting COCONUT’s strengths and the best results to date (e.g. for solar minimum and maximum cases, solar eclipse [2], CME propagation [7], Sun-to-Earth simulations through couplings to EUHFORIA [7] or Icarus [1] or using COCONUT standalone), also including some performance considerations and insights into future work.
REFERENCES
[1] Baratashvili, T., Brchnelova, M., Linan, L., Lani, A., Poedts, S. (2024). The operational-ready full 3D MHD model from Sun to Earth: COCONUT + Icarus. Astronomy & Astrophysics, 690, Art.No. A184. doi: 10.1051/0004-6361/202449389.
[2] Baratashvili, T., Wang, H., Sorokina, D., Lani, A., Poedts, S. (2026). Modelling the total solar eclipse in 2024 with COCONUT. Astronomy & Astrophysics, 705, Art.No. A145. doi: 10.1051/0004-6361/202556300.
[3] Brchnelova, M., Zhang, F., Leitner, P., Perri, B., Lani, A., Poedts, S. (2022). Effects of Mesh Topology on MHD Solution Features in Coronal Simulations. Journal Of Plasma Physics, 88 (2), Art.No. 905880205, 1-29. doi: 10.1017/S0022377822000241.
[4] Brchnelova, M., Kuźma, B., Zhang, F., Lani, A., Poedts, S. (2023). COCONUT-MF: Two-fluid ion-neutral global coronal modelling. Astronomy & Astrophysics, 678, Art.No. A117. doi: 10.1051/0004-6361/202346525.
[5] Kuźma, B., Brchnelova, M., Perri, B., Baratashvili, T., Zhang, F., Lani, A., Poedts, S. (2023). COCONUT, a novel fast-converging MHD model for solar corona simulations: III. Impact of the pre-processing of the magnetic map on the modeling of the solar cycle activity and comparison with observations. Astrophysical Journal, 942, Art.No. 31. doi: 10.3847/1538-4357/aca483.
[6] Linan, L., Regnault, F., Perri, B., Brchnelova, M., Kuźma, B., Lani, A., Poedts, S., Schmieder, B. (2023). Self-consistent propagation of flux ropes in realistic coronal simulations. Astronomy & Astrophysics, 675, Art.No. A101. doi: 10.1051/0004-6361/202346235.
[7] Linan, L., Baratashvili, T., Lani, A., Schmieder, B., Brchnelova, M., Guo, J.H., Poedts, S. (2025). CME propagation in the dynamically coupled space weather tool: COCONUT + EUHFORIA. Astronomy & Astrophysics, 693, Art.No. A229. doi: 10.1051/0004-6361/202451854.
[8] Murteira, J., Brchnelova, M., Lani, A., Poedts, S. (2025). Magnetogram filtering techniques for global coronal modelling. RAS techniques and instruments, 4, Art.No. rzaf030, 1-15. doi: 10.1093/rasti/rzaf030.
[9] Perri, B., Leitner, P., Brchnelova, M., Baratashvili, T., Kuźma, B., Zhang, F., Lani, A., Poedts, S. with Perri, B. (joint first author), Leitner, P. (joint first author) (2022). COCONUT, a novel fast-converging MHD model for solar corona simulations: I. Benchmarking and optimization of polytropic solutions. Astrophysical Journal, 936, Art.No. 19. doi: 10.3847/1538-4357/ac7237.
[10] Perri, B., Kuźma, B., Brchnelova, M., Baratashvili, T., Zhang, F., Leitner, P., Lani, A., Poedts, S. (2023). COCONUT, a novel fast-converging MHD model for solar corona simulations: II. Assessing the impact of the input magnetic map on space-weather forecasting at minimum of activity. Astrophysical Journal, 943, Art.No. 124. doi: 10.3847/1538-4357/ac9799.
[11] Wang, H., Poedts, S., Lani, A., Linan, L., Baratashvili, T., Zhang, F., Sorokina, D., Jeong, H-J., Li, Y.C., Najafi-Ziyazi, M., Schmieder, B. (2025). Time-evolving coronal modelling of solar maximum around the May 2024 storm by COCONUT. Astronomy & Astrophysics, 702, Art.No. A37. doi: 10.1051/0004-6361/202555760.
| Numerical model | COCONUT |
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