College of Science & Engineering
This group's computational program at MSI centers on pioneering, high fidelity fluid dynamic simulations that address timely and fundamental astrophysical problems, especially those involving the physics of hot, magnetized cosmic plasmas. The simulations use magnetohydrodynamic (MHD) codes developed within the group or by collaborators - including important, complementary physics (e.g., self-gravity, radiative energy balance, relativistic cosmic ray (CR) transport and acceleration, and gravitational interactions with "dark matter" particles). Much of the group's recent effort has gone into developing, in collaboration with the High Performance Group at Cray, Inc., a new generation astrophysical MHD code,"WOMBAT." This code is unique in the astrophysical community in both performance and accuracy. It incorporates state-of-the-art parallelization and vectorization methods along with a unique domain decomposition strategy. It now includes the exceptionally high accuracy WENO 5th order MHD solver along with Constrained Transport of magnetic flux to assure maintenance to machine precision of a divergence-free magnetic field. The group has demonstrated in multiple tests that "WENO-WOMBAT" generally achieves approximately twice the effective resolution of the most popular community MHD codes for a given computational cost. They also have demonstrated sustained single core performance exceeding 20% theoretical on new generation Intel chips and outstanding weak scaling to more than 200,000 cores on external Cray systems (e.g., Blue Waters). The exceptional properties of WENO-WOMBAT are documented in a recent issue of the Astrophysical Journal Supplements. The design aims for superior performance on next generation chip architectures, including GPUs, where vector processing is crucial. With these tools in hand these researchers have for the first time anywhere the ability to simulate the "Holy Grail," cosmological MHD turbulent dynamo. The dynamo is thought (but not verified) to be responsible for amplification of magnetic fields during cosmic structure formation. These fields are observed to be pretty much ubiquitous, but their origins remain problematic. The outstanding and unique capabilities of WENO-WOMBAT open up totally new territories to exploration and position this group at the head of the line to contribute to several vital astrophysical research areas. In addition to the mentioned cosmological questions, these include the basic character of cosmic MHD turbulence, the interactions of hypersonic MHD jets with dynamical cosmic media, and the creation of giant radio emitting structures in galaxy clusters. Additionally, the path forward with WENO-WOMBAT addresses outstanding issues in understanding the origins and interpretation of amazingly rich magnetized structures just now being revealed in and around galaxy clusters by the new generation of radio telescopes that are looking deeper with better spatial and spectral information than could be imagined a few years ago. The structures are visible through emissions by relativistic electrons embedded, accelerated and transported within the local, hot (108 K) plasma. Many of the observed structures appear to be the result of interactions between the local plasma and plasma expelled by high energy plasma jets from the nuclei of embedded galaxies. These interactions are quite complex; WENO-WOMBAT is likely the only code currently able to address these issues successfully
The group is working on three specific projects during 2020:
- Large Scale, High Fidelity MHD Simulations of Galaxy Cluster Formation
- MHD Simulations of Active Galaxy Jets in Galaxy Clusters
This research was featured on the MSI website in October 2014: Computational Astrophysics.