Auto cutcell mesh
auto_cutcell_meshGenerate a cut-cell multi-mesh for fire simulation from triangulated geometry, refining narrow gaps and curved surfaces while enforcing engine tiling constraints.
Instructions
Build a cut-cell multi-mesh deck from &GEOM triangulated shapes (plus OBSTs). Cells shrink where the fluid gap is narrow (gap / gap_cells), the GEOM surface band always gets the finest cell so the engine keeps its cut-cell wall physics there, sharp curvature gets one level finer, and levels change at most 2:1 between neighbouring blocks. Cell sizes are min_cell x 2^k. If the deck has no GEOM this is identical to auto_multimesh. Over budget it relaxes curvature, buffer, gap_cells, then raises min_cell and reports what it changed; a gapped, overlapping or misaligned deck is refused. Engine constraints (engine multimesh ratio_union_grid): (1) every mesh must use CUBIC cells whose size is the finest cell x 2^k (k in 1,2,4,8,16); (2) every mesh boundary and the union extent must land on a fine-grid index that is a multiple of the LARGEST ratio actually used; (3) meshes must tile the domain with no overlap and no gap; (4) a 1:4 or larger ratio makes the engine print an experimental-feature warning and switches it to per-mesh storage (MM2) plus the composite block-CG v2 pressure solve, both automatically. Verify with list_meshes.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| max_cell | Yes | Coarsest cell size (m), e.g. 0.2. Rounded DOWN to min_cell x 2^k. | |
| min_cell | Yes | Finest cell size (m), e.g. 0.05 — used on the GEOM surface band and in narrow gaps. | |
| gap_cells | No | Minimum cells across a narrow gap (default 4, floor 3). |