Select a boundary region

Use a boundary region to apply a condition to all or part of an axis-aligned domain or cuboid face.

Select the owning surface

Put the boundary entry in:

• domain.boundary_conditions for an exterior-domain face; or
• an insulating cuboid’s boundary_conditions for a component face.

Explicit boundary conditions are not assigned to conducting components, compact thermal models, or CAD components.

Select the face and shape

Use full when the condition covers an entire face:

{
  "boundary": {
    "full": {
      "side": "x_min"
    }
  },
  "condition": {
    "velocity_inlet": {
      "speed": 1.0,
      "temperature": 20.0
    }
  }
}

Use a rectangle, circle, or annulus for a partial opening. For a rectangle on an x face, center and size use the y and z coordinates:

{
  "boundary": {
    "rectangle": {
      "side": "x_min",
      "center": [0.05, 0.04],
      "size": [0.02, 0.015],
      "mesh_resolution": 8
    }
  },
  "condition": {
    "velocity_inlet": {
      "speed": 1.0,
      "temperature": 20.0
    }
  }
}

On a y face the two coordinates are x and z; on a z face they are x and y. Coordinates are measured in the global domain coordinate system, even when the boundary region belongs to a component.

Do not combine a full boundary region with another condition on the same face. Partial boundary regions replace the default behavior only on their selected cells.

See also

• Boundary placement and defaults explains the defaults being overridden.
• API reference defines every shape available for boundary regions and every boundary condition.