In the filter FilterLagrangianPoints, Lagrangian points can be tracked in parallel. In this
filter, Points are stored in two copies. One copy is the stationary points, which are fixed in the
thread. Another copy is the mobile points, which can move based on the mesh partition. When
evaluating the physics values on the mobile points, we first search the local mesh partition. For
the points that are not found in the local partition, their information is packed into a
global array and synced for all thread. A global search is performed. Once the thread
whose mesh partition contains some unfound mobile points, these points in the
mobile copy are moved to the corresponding thread. After evaluation the physics
values on the mobile points, the data are sent back to thread which contains the
corresponding stationary points. The design detail of this filter is shown in figure 12.3.1.0.
