Here the most important terminology and variable names are collected.
Terminology
| Term | Description |
| AMR | Adaptive Mesh Refinement |
| quadtree/octree | Afivo uses adaptively refined grids of the quadtree and octree type |
| box | A box contains \(N^D\) grid cells, where \(D\) is the problem dimension and \(N\) is e.g. 8 or 16, see Important data structures |
| tree | The full grid, containing all the boxes at all refinement levels |
| neighbors | A box can have neighbors (adjacent boxes at the same refinement level) in the x, y, and z-direction |
| parent | When a box is refined, it becomes a parent (since it now has refined 'children') |
| children | When a box is refined, it is covered by its children, which 4 (2D) or 8 (3D) boxes with half the grid spacing |
| leaf | A box that is not refined / which does not have children |
Variable names
| name | Typically used for |
| tree | Data structure containing the full grid |
| boxes | List of all the boxes, at all refinement levels |
| id | Integer indicating the index of a boxes in the boxes array |
| nc | The number of cells along each dimension of a box (a box contains \(nc^D\) cells) |
| iv | Index of a variable |
| nb | Index giving the direction to a neighboring box (left, right, ...), from 1 to 2 * NDIM |
| lvl | Integer indicating the refinement level (1, 2, ...) |
| neighbors | List of \(2D\) integers to indicate the neighbors of a box. They can be positive (index of neighbor in boxes array), zero (refinement boundary) or negative (physical boundary) |
| parent | An integer with the index of the parent, or zero if there is no parent |
| children | List of \(2^D\) integers with the indices of the children, and zero if there are no children |
af_no_box | The integer value zero |
| fc | face-centered |
| cc | cell-centered |
