A 3D Unstructured Mesh-based Global Impurity Transport Code *

This presentation will overview the GITRm code which is a fully 3D mesh-based impurity transport code based on the physics models contained in the GITR impurity transport code. GITRm builds on the PUMIPic library which is an unstructured mesh PIC infrastructure which supports the use of highly anisotropic meshes that allow for the effective distribution of calculation effort to critical regions of the domain. PUMIPic’s scalability is supported by the use of both distributed mesh and particle representations. The presentation will briefly introduce PUMIPic with a focus on the implementation of critical operations of importance to impurity transport calculations including particle containment search, distance to boundary in critical regions and dynamic load balancing to account for both the evolving distribution of particles and numbers of particles due to deposition as the simulation proceeds.  Scaling results for cases run on GPU-based supercomputers (e.g., Summit) will be presented. Finally, the status of results obtained to date using GITRm to address specific simulation scenarios will be presented.