4.11. Geometric Paths
[4. Implementation Design]

Modules
	4.11.1. Group Organization
	4.11.2. API Functions
	4.11.3. Spatial Bins

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Detailed Description

Geometric paths store coordinate locations of nodes or particles. In addition:

• The position of each node (x,y,z) varys over time. This requires that the array used to store these positions become a three dimensional array rather than a two dimensional array.

• Since the position is moving, it is difficult to determine what entities intersect a specific region. To address this, the Spatial Bins array can be included.

• There is no connectivity of elements, only strings of locations for a specific geometric entity along its path.

Data sets may be associated with a geometric path group. Individual paths may be inactive for portions of the time range represented by the data. This inactive period could be at the beginning (particle doesn’t start at the start of the time range), in the middle of the time range (particle becomes static or inactive for a period of time), or at the end (particle stops or leaves the domain). In these cases, a data set would be used to store the velocity magnitude of each node at each time. If the velocity magnitude is a NULL data flag, the node is inactive at that time.

In some known applications the number of particles may increase over time. The geometric paths group is setup in such a way that particles may be added after the group is initialized. Datasets associated with these groups will also need to expand. The particle data is written one timestep at a time and is stored in a chunked layout (necessary to allow for growth). It might be advantageous to convert this to a contiguous layout using the repack command-line utility for faster data access (post-processing).