name: gmsh-meshing-initialization-and-model-management
description: 'Sub-skill of gmsh-meshing: Initialization and Model Management (+6).'
version: 1.0.0
category: engineering
type: reference
scripts_exempt: true
Initialization and Model Management (+6)
Initialization and Model Management
import gmsh
# Initialize
gmsh.initialize()
gmsh.option.setNumber("General.Verbosity", 3)
# Create a new model
gmsh.model.add("my_model")
*See sub-skills for full details.*
## Built-in Kernel (gmsh.model.geo)
```python
# Points
p1 = gmsh.model.geo.addPoint(0, 0, 0, meshSize=1.0)
p2 = gmsh.model.geo.addPoint(10, 0, 0, meshSize=1.0)
p3 = gmsh.model.geo.addPoint(10, 5, 0, meshSize=0.5)
# Lines
l1 = gmsh.model.geo.addLine(p1, p2)
l2 = gmsh.model.geo.addLine(p2, p3)
*See sub-skills for full details.*
## OpenCASCADE Kernel (gmsh.model.occ)
```python
# Box: addBox(x, y, z, dx, dy, dz)
box = gmsh.model.occ.addBox(0, 0, 0, 100, 20, 10)
# Sphere: addSphere(xc, yc, zc, radius)
sphere = gmsh.model.occ.addSphere(0, 0, 0, 5.0)
# Cylinder: addCylinder(x, y, z, dx, dy, dz, r)
cyl = gmsh.model.occ.addCylinder(0, 0, 0, 0, 0, 10, 5.0)
*See sub-skills for full details.*
## Mesh Generation (gmsh.model.mesh)
```python
# Generate mesh
gmsh.model.mesh.generate(1) # 1D
gmsh.model.mesh.generate(2) # 2D surface
gmsh.model.mesh.generate(3) # 3D volume
# Recombine triangles to quads
gmsh.model.mesh.recombine()
# Set transfinite constraints
*See sub-skills for full details.*
## Options (gmsh.option)
```python
# Mesh algorithm selection
gmsh.option.setNumber("Mesh.Algorithm", 6) # Frontal-Delaunay 2D
gmsh.option.setNumber("Mesh.Algorithm3D", 1) # Delaunay 3D
# Size controls
gmsh.option.setNumber("Mesh.MeshSizeFactor", 0.5)
gmsh.option.setNumber("Mesh.MeshSizeMin", 0.1)
gmsh.option.setNumber("Mesh.MeshSizeMax", 2.0)
gmsh.option.setNumber("Mesh.MeshSizeFromCurvature", 12)
*See sub-skills for full details.*
## Mesh Size Fields (gmsh.model.mesh.field)
```python
# Distance field — distance from curves or points
f_dist = gmsh.model.mesh.field.add("Distance")
gmsh.model.mesh.field.setNumbers(f_dist, "CurvesList", [1, 2, 3])
gmsh.model.mesh.field.setNumber(f_dist, "Sampling", 100)
# Threshold field — size based on distance
f_thresh = gmsh.model.mesh.field.add("Threshold")
gmsh.model.mesh.field.setNumber(f_thresh, "InField", f_dist)
gmsh.model.mesh.field.setNumber(f_thresh, "SizeMin", 0.1) # size at DistMin
*See sub-skills for full details.*
## File I/O
```python
# Write mesh
gmsh.write("output.msh") # Default format
gmsh.write("output.stl") # STL
gmsh.write("output.vtk") # VTK
gmsh.write("output.unv") # Universal
gmsh.write("output.bdf") # Nastran
# Write specific format version
gmsh.option.setNumber("Mesh.MshFileVersion", 2.2)
*See sub-skills for full details.*
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