Add a cuboid component

Add an axis-aligned cuboid when a box captures the component geometry closely enough for the required flow and thermal results. Cuboid components can represent either a volume or a zero-thickness surface.

Define its position and size

Add an object to cuboid_components with a unique tag. Set bbox.origin to its minimum [x, y, z] corner and bbox.size to its dimensions, all in meters. A volumetric cuboid has three positive dimensions:

{
  "tag": "power_module",
  "bbox": {
    "origin": [0.04, 0.02, 0.005],
    "size": [0.03, 0.02, 0.008]
  },
  "thermal_model": {
    ...
  }
}

Keep the cuboid inside the computational domain and avoid overlaps with other components. Its faces remain aligned with the coordinate axes; use an imported CAD component when rotation or non-box geometry matters.

Choose its thermal behavior

For a volumetric cuboid, set thermal_model according to the job the component performs:

• use insulating for a flow obstruction with no internal heat transfer;
• use conducting to resolve temperature through a solid;
• use a compact thermal model to predict a chip’s junction temperature from thermal resistances.

Refine and check the component

Add max_cell_size to the component if the global mesh does not retain its thickness or the surrounding clearances:

{
  "tag": "power_module",
  "max_cell_size": 0.001
}

Merge this field into the component rather than adding a second object with the same tag. Run a dry run and inspect the resulting solid and fluid regions. Confirm that the component occupies the intended cells, leaves required flow passages open, and contacts the intended thermal regions.

Represent a thin object with a surface

Set exactly one dimension in bbox.size to zero to create a surface; the other two dimensions must remain positive. Use this for objects much thinner than the scale of interest, such as thermal interface materials (TIMs) or thin airflow baffles, so their thickness does not require very small mesh cells.

Surface components support two thermal models:

• "insulating" creates an impermeable sheet with adiabatic thermal defaults;
• conducting_surface adds thermal resistance normal to the sheet, determined by its thickness divided by its conductivity.

The thermal model’s thickness represents the unmeshed material thickness; it does not expand the bounding box. See Add a thermal interface layer for a TIM example and the contact setup workflow.

See also

• CAD voxelization explains the mesh representation when replacing a cuboid with rotated or more detailed CAD geometry.
• Conducting and insulating domains explains which regions participate in the temperature solve.
• Compact thermal models explains the resistor networks used to calculate junction temperature.
• Geometry and the computational domain explains how components displace fluid.
• Configure the mesh shows how to refine components and nearby clearances.
• Tutorial: Add solid components to the duct uses cuboid components in a complete electronics cooling simulation.