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betti volume poly

Fill a closed surface with polyhedra, for finite volumes, with prism layers on walls.

volume module Granted on request: see access and licensing.

Usage

Shell

betti volume poly [flags] in out

in is a closed surface mesh, or a STEP, IGES, JT or Parasolid part (with the cad module too). The surface must be closed, facing outward, without crossings: run betti fix repair first if not. Each solid it encloses is a region; voids stay empty. A CAD part's surface is meshed at -size first (2% of the part if unset), each CAD face a tag. The boundary faces are pieces of the surface's triangles, merged where flat and of one tag.

With -layers, the cells next to the walls (the boundary faces of the tags -layers-on names, or all) are layers of prisms, the first -first high and each -growth times the one below; where cells would fold, the layers are thinner.

In a script this is volume.poly(…), its flags as keywords; for coding agents, the tool volume_poly.

Examples

Shell

betti volume poly part.obj case/constant/polyMesh
betti volume poly -size 2% -layers 5 -first 0.1 -layers-on wall duct.obj duct.vtu

Formats, by the extension of out

.vtu	VTK unstructured grid: cells, regions in the cell data array "region"; no boundary tags (use .msh for those)
polyMesh	an OpenFOAM polyMesh folder (a path ending in polyMesh): every cell by its faces, regions as cell zones, boundary tags as patches, walls but those named inlet, outlet or symmetry

Flags

Flag	Takes	Default	Meaning
`-first`	length or number	none	the first layer's height, such as 0.1 or 0.05%, with `-layers`
`-growth`	number	`1.2`	each layer's height over the one below it, with `-layers`
`-keep-surface`	switch	off	keep the surface's triangles as the boundary: no points added on it; fails where the tetrahedra need one
`-layers`	integer	none	layers of prisms on the walls, for boundary layers; 0 for none
`-layers-on`	text	none	the boundary tags the layers grow from, by number or name, separated by commas; unset, all
`-min-dihedral`	number	`10`	smallest dihedral angle, in degrees, tetrahedra are improved towards
`-radius-edge`	number	`2`	largest ratio of a tetrahedron's circumradius to its shortest edge (0.61 for a regular one)
`-size`	length or number	none	target edge length, such as 2 or 1%; unset, cells as large as their shape and the surface allow

Output flags

Flag	Takes	Default	Meaning
`-json`	switch	off	print the result as JSON
`-q`	switch	off	print nothing but errors
`-skip`	names	none	switch off steps of the work by their names, separated by commas, as the built-in help lists them
`-v`	switch	off	also show the stages of each step, and their times

This page is generated from betti help volume poly. Lengths are absolute, or a percentage of the part's bounding-box diagonal, as in -size 1%.