Figure 1

Example schematic illustrating data movement of block-structured grids from the simulation MPI group to the sidecar group when running in-transit. Each Box is uniquely numbered, and Boxes shaded in the same color are located on the same MPI process, whose rank is identified in parentheses. In this example, a grid composed of 16 Boxes moves from a distribution across 4 processes, with 4 Boxes per process, to a new distribution across 2 processes, with 8 Boxes per process.