1. CCA (unstructured) Mesh & Data Manager (aka Central Data Object) Component Abstractions - prelim thoughts & status - CCA Working Group Meeting Gatlinburg, TN 12-7-00 Robert Clay, Lori Freitag, Ray Loy, & Lee Taylor

2. Some Basic Definitions Mesh (unstructured) – that ‘class’ which holds nodes (coordinates) and elements (connectivity). Data Manager – that ‘class’ which holds Fields, used in association with a Mesh (and mesh extents). Mesh extent – some part (subset) of a mesh, e.g., all the nodes. Field – where you put results (e.g., pressure, temp, displacement) values, defined on a mesh extent. Fields have ‘data type’ (e.g., int, double, complex) and ‘math type’ (e.g., scalar, vector, symmetric tensor – mininal case is scalar).

3. Brief Status Report (‘unstructured’ group) We’ve met three times (SC00, grid-con last week, yesterday), where we primarily worked to inform each other and get on the same page. –Several models exist in pre-CCA-blessed state, and they share core functionality (i.e., mesh/field I/O capabilities) –None of these have been blessed, since we’re just getting the group underway. –TeraScale has relatively complete (probably too complete for this group ) model, but the group has not settled on any interfaces yet. Yesterday we listed a basic set of definitions & capabilities that we agree on – so we have a concrete start. Hopefully, will have a meeting in early Jan 01 to hammer out some prototype API’s for mesh & data manager (field) classes/components.

4. Agreed-Upon Requirements Meshes have nodes (vertices), elements, and dimensionality. –Nodes have coodinates. –Elements have connectivities. –Dimension (e.g., 1D,2D, or 3D)is homogeneous across mesh. Fields are defined on meshes (mesh extents). [fields are not necessarily embedded in meshes] –Fields have ‘data’ and ‘math’ types. –Fields can be registered/instantiated w/ a unique handle. –Fields have get/put type operations (range, single, all). Subsetting capability is required (still in discussion) (e.g., to identify BC’s). SPMD capability (at least not precluded) – will impact (i.e., add functions to) the API’s.

5. ‘Optional’ Items - or at least 2 nd tier requirements - Edges and connectivity. Faces and connectivity. Mesh modification & associated field interpolation (tough problem). Mesh instancing (may be required for some ‘extreme’ problems). Fields being saved to file (or other IO stream).