Mesh Editing & History

The preview is not read-only: the Edit and Mesh Modification sidebar sections apply in-place operations to the loaded mesh, all recorded into an undoable, replayable operation history. The edited mesh is what File ▸ Save / Export writes to disk.

Linear → Quadratic

Convert Linear → Quadratic (Mesh Modification) inserts mid-edge nodes to raise every linear cell to its quadratic ("serendipity") counterpart:

Linear	Quadratic
Triangle2D3	Triangle2D6
Quadrilateral2D4	Quadrilateral2D8
Tetrahedra3D4	Tetrahedra3D10
Hexahedra3D8	Hexahedra3D20
Prism3D6 (wedge)	Prism3D15
Pyramid3D5	Pyramid3D13
Line2	Line3

Adjacent cells that share an edge get a single welded mid-edge node, nodal fields are interpolated at the new nodes, and SubModelParts are extended with the mid nodes of their fully-enclosed edges. Cells that are already quadratic or have no quadratic counterpart are left untouched. The new mid nodes are drawn as a semitransparent Quadratic mid-nodes overlay (a toggleable outline row), so you can see exactly what was added.

For MMG-based remeshing and level-set splitting, see MMG Remesh & Level-set.

Additional mesh operations

The Mesh Modification section also surfaces the extension's bundled meshio++ as an oracle — it computes something (moved coordinates, a node permutation, a per-cell label) that gets applied onto your own mesh, so SubModelParts, ids and material assignments are never lost the way a raw meshio++ round-trip would lose them — plus several operations implemented natively. These, together with Convert Linear → Quadratic, Remesh (MMG), Level-set split (MMG) and Set element radius, are grouped into six collapsible subcategories — Element order & topology, Remeshing (MMG), Smoothing & renumbering, Selection & combination, Fields, and Sphere elements — so the section reads as a short list of categories rather than a long flat list of forms:

Smooth, Reorder, Partition and Merge mesh run asynchronously — the same inline progress bar and play/stop cancel button as the MMG operations. The rest apply instantly. Every one of these joins the same undoable operation history and JSON recipe as the operations above, and is reachable from the mesh_transform tool on the MCP server, same as every other mesh operation, for scripting.

Reading the screenshots below

Where an operation changes geometry or topology, the shot places the mesh before it (blue, left) next to the result (orange, right) in one view, with the operation's own form open in the sidebar showing the exact parameters that produced it. Where it instead produces a field, the shot colours the result by that new variable through the Field panel.

Element order & topology

Refine

Uniform subdivision: triangles/quadrilaterals/tetrahedra/hexahedra/wedges split into 4 or 8 children, lines into 2, up to 4 levels. Shared edges and faces are deduplicated to a single new node — so there are no hanging nodes — nodal fields interpolate exactly at the new nodes, and elemental/conditional fields and SubModelPart membership extend to the children. The 8 elements above become 64; a second level would make it 512, which is why the level count is capped.

Quadratic → Linear

The inverse of Convert Linear → Quadratic: drops the mid-side nodes and restores the underlying linear cell type (Tetrahedra3D10 → Tetrahedra3D4, Hexahedra3D20 → Hexahedra3D8, …), then removes whatever is left unreferenced. With Node IDs turned on the difference is literal — the same 8 cells, 81 nodes before and 27 after.

Simplexify

Converts non-simplex cells to simplices: hexahedra → 6 tetrahedra, wedges → 3, pyramids → 2, quadrilaterals → 2 triangles. The first child keeps the parent's id and its siblings get fresh ones, with elemental/conditional fields and SubModelPart membership replicated to each. A mesh that is already all-simplex is a no-op.

Smoothing & renumbering

Smooth

Taubin (the default — it alternates a shrink and an anti-shrink pass, so a closed surface keeps its volume) or Laplacian mesh smoothing. Boundary nodes and sharp-feature edges are pinned by default, and a move that would invert a cell is rejected by default (guard inversion). Only coordinates change — node count, connectivity, SubModelParts and every field come through untouched, which is what makes this safe to apply to a mesh you have already set a case up on.

Reorder

Renumbers nodes for RCM bandwidth reduction, or along a Morton / Hilbert space-filling curve for cache locality. This is the one operation with nothing to see in the geometry — it is a pure permutation, so the shot turns Node IDs on, since the numbering is precisely what changed. The coordinates, the cells, the SubModelParts and the fields are all the same mesh, just renumbered; the payoff is in how a solver's sparse matrix assembles.

Partition

Space-filling-curve domain decomposition into N parts balanced by cell count, attached as a real Kratos PARTITION_INDEX Elemental field (so it exports, and Kratos can read it) and optionally also created as one SubModelPart per part. Colouring by that field through the Field panel is how you check the result, as above. The bundled WASM build has no KaHIP, so only the space-filling-curve method is offered — good for previewing a decomposition and for a quick run, but it minimizes no edge cut and is not a substitute for METIS.

Selection & combination

Crop

Keeps only the cells inside a bounding box or on one side of a plane, either requiring all of a cell's nodes to qualify or any one of them; anything left unreferenced afterwards is removed. SubModelParts narrow to the survivors rather than disappearing. Above, a box cutting at x = 4.5 keeps half the block.

Merge mesh

Appends another mesh file's nodes and cells, offsetting their ids past the current mesh's maximum and wrapping the merged-in geometry in its own SubModelPart (MergedMesh above) so you can still tell the two apart — frame it, export it or delete it from the outline like any other part. Optionally welds coincident nodes across the seam, using the same tolerance grid as Merge coincident nodes.

Fields

Field calculator

Derives a new nodal/elemental/conditional field from a formula over the node or cell-centroid coordinates (x, y, z) and any existing field at that location — a vector field's components are reachable as NAME_X/NAME_Y/ NAME_Z. It uses the same safe recursive-descent evaluator as the MMG size = ƒ(h) remesh mode, never eval, which matters because a formula can arrive from a saved recipe or a problem archive. A bad formula is rejected inline before anything is applied; a value that cannot be computed (a referenced field is silent at that entity) drops that row, while a genuine infinity from e.g. 1/0 is kept.

Average field

Moves a field between the nodal and elemental/conditional locations by averaging: nodal → elemental takes the mean over a cell's own nodes, elemental → nodal the mean over a node's incident cells (unweighted, not measure-weighted). Above it turns the nodal RADIAL_DISTANCE from the field calculator into a per-element one — note the flat, per-cell colouring against the smooth nodal gradient in the previous shot.

Export skin

Advanced ▸ Export skin… is not an in-place edit but an export: it extracts the boundary of the mesh's volume cells (plus any pre-existing surface cells) as a standalone surface mesh and writes it to a file of your choice, through the same format picker as File ▸ Export. It is a native boundary-face walk — a face seen by exactly one cell is boundary — rather than meshio++'s own surface/skin extractors, so SubModelParts survive the extraction (narrowed to node membership; element/condition membership cannot follow, since the skin's faces get fresh entity ids). Also reachable from the mesh_extract_skin MCP tool.

Edit operations

The Edit section hosts interactive, form-driven operations — enter the values inline and press Apply (or Enter in a field):

• Remove orphan nodes — drop nodes referenced by no cell and listed in no SubModelPart.
• Merge coincident nodes — weld nodes within a tolerance into one.
• Scale — per-axis scale factors (x, y, z).
• Translate — offset by (dx, dy, dz).
• Rotate — by an angle in degrees about the X, Y, or Z axis, through a configurable center point (defaults to the origin).
• Delete a SubModelPart — triggered from the ✕ button on a SubModelPart row in the outline tree; its entities and any orphaned nodes are removed.
• Set element radius — set or scale the RADIUS of one-node (sphere/particle) elements, optionally limited to one SubModelPart. See Sphere / Particle Elements.

Each transform form is a collapsible dropdown — click its title to expand its inputs.

Operation history

Every applied edit — including Linear → Quadratic and the MMG operations — is recorded in the history:

• Undo / Redo / Clear controls.
• A clickable list of the applied operations. Clicking an entry partially reverts the mesh to that step; later steps stay redoable until you apply a new operation.

Because the operations are pure and deterministic, the history is a replayable recipe:

• Save operations… writes the applied operations to a JSON file.
• Load operations… replays a recipe onto the current mesh.

TIP

The history is tied to the loaded mesh. Re-reading the file from disk — or, for a VTK time series, changing the frame — starts a fresh history. Use File ▸ Save / Export to persist the edited mesh before reloading.