Multi-Block with Splitting

A multi-block input grid (for example one read from a Tortuga file with ImportTurtleGrid) is split with SplitMultiBlock:

newBlocks, newBndInfo, newInterInfo = SplitMultiBlock(blocks, splitRequests, bndInfo, interInfo)

• blocks is a vector of [2, Ni, Nj] arrays.
• splitRequests lists, for each block to split, the i indices and the j indices to split at. It is either a vector of (blockId, [[i_splits...], [j_splits...]]) tuples or a Dict(blockId => [[i_splits...], [j_splits...]]).
• bndInfo and interInfo use the package's 1-based indexing.

Split propagation

Point-to-point matching across block interfaces must survive the split. A split line that ends on an interface is therefore propagated into the neighbouring block at the matching index, and from there onward until no new splits appear. For example, in a 2×2 layout, a j-split of the lower-left block is carried across the vertical interface into the lower-right block. The upper blocks are left alone.

Before                 After splitting block 1 at j = s
┌─────┬─────┐          ┌─────┬─────┐
│  3  │  4  │          │  5  │  6  │
├─────┼─────┤          ├─────┼─────┤
│  1  │  2  │          │  2  │  4  │
└─────┴─────┘          ├─────┼─────┤
                       │  1  │  3  │
                       └─────┴─────┘

Blocks are renumbered globally after splitting. Boundary faces are reassigned to the sub-blocks that touch them, and interfaces are created between the new sub-blocks and remapped onto the neighbours.

Single-block input

For a single block, GenerateGrid uses SplitBlock(block, splitLocations, bndInfo, interInfo), where splitLocations = [[i_splits...], [j_splits...]]; see Single Block with Splitting.