Use an Import node () to import a mesh from a file, from another meshing sequence, or from a mesh part. To position, rotate, and scale the mesh, use one or several Transform attributes.

To import additional meshes, add another Import node. Then COMSOL Multiphysics adds the elements of the newly imported mesh to the existing mesh.

In the Source list, choose the type of data to import: Any importable file, Meshing sequence (if applicable meshing sequences are available), and COMSOL Multiphysics file are always available. In addition to the native file formats, you can choose NASTRAN file and Sectionwise file in 2D and 3D. In 3D you can also choose STL file (stereolithography file), PLY file (Polygon File Format or Stanford Triangle Format file), 3MF file (3D Manufacturing Format file), and VRML file (Virtual Reality Modeling Language file). Choose Geometry sequence to import a triangle mesh of a Component’s geometry. Choose Dataset to import the visualization mesh of a Filter or Partition dataset. This option is only available if there is at least one Filter or Partition node under Datasets in Results.

For file import, specify the filename in the Filename field or click the Browse button (). You can also click the downward arrow beside the Browse button and choose Browse From () to open the fullscreen Select File window. Click the downward arrow for the Location menu () to choose Show in Auxiliary Data () to move to the row for this file in the Auxiliary Data window, Copy Location (), and (if you have copied a file location) Paste Location ().

For import from another mesh in the model, select a meshing sequence or mesh part from the Mesh list below. To import a meshing sequence or a mesh part, click the Import button. For import of a dataset in the model, select a Filter or Partition dataset from the Dataset list below.

If you have changed some property, the software automatically reimports the mesh when you click a build button. For import of a meshing sequence, select Build source mesh automatically (selected by default) to automatically build the source sequence and reimport the current version of the mesh. This is required when running a parametric sweep over some parameter that affects the source mesh.

In 3D, you can import 3D meshes and planar 2D meshes from COMSOL Multiphysics files (.mphtxt or .mphbin). Planar 2D meshes, imported to a 3D component, always appear at z = 0.

When you import a mesh from a COMSOL Multiphysics file that contains mesh selections, you need to select the Import selections checkbox (selected by default) to import the selections together with the mesh. If you choose to import mesh selections, corresponding selections are created and appear in the Domain Selections, Boundary Selections, Edge Selections, or Point Selections sections, depending on space dimension and the entity level for the imported selections. You can use the imported selections, for example, to add as a selection to a dataset or plot during results processing. See also Entity Selections below.

To import the second-order elements in 2D and 3D as linear elements (that is, ignoring node points not in element vertices), select the Import as linear elements checkbox (not selected by default).

In 3D, select the Import domain elements checkbox to import volumetric elements, such as tetrahedrons, hexahedrons, prisms, and pyramids. Clear this checkbox to only import boundary elements. The checkbox is selected by default for the following options from the Source list: Meshing Sequence, COMSOL Multiphysics file, NASTRAN file, and Sectionwise file. However, when the software adds the Import operation automatically in a new meshing sequence, the default is OFF for Source: Meshing Sequence to allow for editing.

This setting is available with the following option from the Source list: Meshing Sequence.

In 3D, select the Import unmeshed domains to import domain information from the source meshing sequence. Clear this checkbox to get voids inside surface meshes that form watertight regions. Domains can be created later, if needed, using the Create Domains operation. When Source is set to COMSOL Multiphysics file, NASTRAN, or Sectionwise, the default is ON. For Source: Sequence, the default depends on how the operation is added. When you add the Import operation manually from The Mesh Toolbar or The Model Builder Context Menu, the default is OFF. When the software adds the Import operation automatically in a new meshing sequence, the default is ON.

These settings are available with the following options from the Source list: COMSOL Multiphysics file, Dataset, STL file, VRML file, NASTRAN file, PLY file, Sectionwise file, and 3MF file.

When a mesh is imported into COMSOL Multiphysics, the operation automatically determines a partitioning of the mesh into domains, boundaries, edges, and points. If the automatically performed partitioning does not match the requirements, you can use the Boundary partitioning list to control the partitioning:

The partitioning algorithm aims to split boundary elements (edge elements in 2D, face elements in 3D) into boundary entities in such a way that no large angles appear between neighboring elements within the same boundary entity. In 2D, you can limit the angle between any two elements within the same boundary entity using the Maximum angle within boundary field. The maximum accepted neighbor angle can be set using the Maximum neighbor angle field (default: 40 degrees).

If the Detect planar faces checkbox (3D) or the Detect straight edges checkbox (2D) is selected (both are selected by default), the mesh import detects (approximately) planar faces or straight edges, respectively. The minimum size of a straight or planar boundary entity, relative to the entire boundary, can be set using the Minimum relative length field (2D) and Minimum relative area field (3D). The maximum accepted angle (in degrees) between elements for a boundary to be considered straight or planar can be set using the Maximum deviation angle field. If the Detect adjacent fillet faces checkbox (3D) is selected, the algorithm also searches for adjacent groups of boundary elements that form cylindrical faces.

The partitioning algorithm aims to split edge elements into edge entities in such a way that no large angles appear between neighboring elements within the same edge entity. The maximum accepted neighbor angle can be set using the Maximum edge neighbor angle field (default: 60 degrees).

If the Detect planar edges checkbox is selected (it is selected by default), the mesh import detects (approximately) planar edges. The Detection parameter specifies to which extent the operation searches for planar edges. Use the slider to tune the detection level, where Strict means that only fully planar edges are searched for, and Tolerant means that the algorithm searches for planar edges with a wider tolerance. You can also enter the parameter value directly as a value between 0 (strict) and 1 (tolerant).

If the Detect straight edges checkbox is selected (it is selected by default), the mesh import detects (approximately) straight edges. The Detection parameter specifies to which extent the operation searches for straight edges. Use the slider to tune the detection level, where Strict means that only fully straight edges are searched for, and Tolerant means that the algorithm searches for straight edges with a wider tolerance. You can also enter the parameter value directly as a value between 0 (strict) and 1 (tolerant).

From the Minimum edge length list, choose one of the following options: Automatic (the default), Relative, or Absolute to specify the minimum required length of an edge to be detected. If you select Relative, specify a minimum relative length in the Minimum relative length field that appears, and if you select Absolute, specify a minimum absolute length in the Minimum absolute length field that appears.

The sections Domain Selections, Boundary Selections, Edge Selections (3D only), and Point Selections appear after building the Import operation. The selections are generated during the import based on selections defined in the source. In the Name column, the name of each selection appears. For COMSOL Multiphysics file import, the Name in file column contains the names available in the file. Select the name in the Name column to highlight the selection in the Graphics window. You can change the name of a selection by editing the corresponding table entry in the Name column. If the Keep checkbox (ON by default) is selected, the Physics checkbox (Instance in parts), when selected (ON by default), makes that selection also available when defining, for example, physics and materials as well as in instances of the mesh part.

The selections can be used to specify entity selections in operations and attributes within the same mesh-based geometry or meshing sequence and, if the mesh defines the component’s geometric model, for physics and material settings. For more information about the component’s geometric model, see The Mesh Node.