Meshing Updates

COMSOL Multiphysics® version 6.0 brings significant meshing improvements that make it easier and more efficient to set up simulations on imported mesh data, such as support for uniting meshes, boundary layer meshing, and curved elements. Browse all of the mesh updates below.

Uniting Imported Meshes

The new Union operation can be used to unite intersecting meshes. Use this operation to combine meshes, such as two imported meshes, or to combine an imported mesh with a geometry drawn in either COMSOL Multiphysics® or an external CAD software. As shown in the image below, an imported STL mesh is united with the mesh of a block, where the block has been drawn in the geometry sequence, meshed, and then imported into the same meshing sequence as the STL mesh.

An intersected vertebra model with a block showing the surface mesh.
The intersection of an imported STL mesh of a vertebra with a surface mesh of a block, computed by the new Union operation for meshes.

Boundary Layer Meshing for Imported Meshes

In COMSOL Multiphysics® version 6.0, it is straightforward to add boundary layer elements to all meshes, including imported meshes. To adapt an imported mesh to, for example, a fluid flow simulation, you can simply add a Boundary Layers operation to the sequence of mesh operations. This is shown in the Analyzing Porous Structures on the Microscopic Scale tutorial model.

A porous structure model showing the boundary layer elements in blue and the imported mesh in gray.
Boundary layer elements (blue) added to an imported mesh (gray) defining a porous structure.

Curved Elements for Imported Meshes

Curved elements can be reconstructed for meshes imported from file even in a case where they define linear elements. This includes STL, PLY, 3MF, and NASTRAN files. COMSOL Multiphysics® version 6.0 automatically estimates the shape of the faces and edges from the mesh structure to define curved elements specified by the discretization of the physics. There is no extra step needed and the curved elements are already set up and in use once you click the Compute button. To show the curved elements as displayed in the figure below, add a Mesh plot, and in the settings for the Mesh dataset, select a higher-order geometry shape function.

An imported geometry showing the mesh with linear elements.
Imported mesh with linear elements that is used for the computation.

An imported geometry showing the curved mesh in green-yellow triangular elements.
Imported mesh with corresponding curved mesh that is used for the computation.

Transforming Imported Meshes

It is now possible to move, rotate, and scale an imported mesh using Transform attributes. To rotate the mesh around several axes, add several Transform attributes to the Import node. Previously, transformations were only supported in the geometry sequence.

Improved Usability for Mesh Editing

When you are meshing a geometry, you now have access to all operations for editing the mesh, including those that modify the number of geometric entities (the topology of the geometry), such as the new Union operation for meshes. These improvements make it easier to combine, in the same Component of your model, geometry created under the Geometry node with imported meshes, such as STL files.

The COMSOL Multiphysics UI showing the Model Builder with the Intersect with Plane node highlighted, the corresponding Settings window, and an imported model in the Graphics window.
Model where an imported STL mesh of a vertebra is combined with a geometry block.

Boundary Layer Meshing Improvements

COMSOL Multiphysics® version 6.0 includes improved support for boundary layer meshing on isolated boundaries. The boundary layer elements on interior and exterior wall boundaries now join smoothly at the intersections. This new way of joining boundary layer elements better resolves the physics that are close to such corners.

A mixer model mesh in blue, gray, and orange, with an inset showing a smaller portion of the orange prism elements.
A mixer model with boundary layer elements (blue and orange) along the wall boundaries. The prism elements (orange) in the boundary layers are generated where the isolated boundaries of the baffles connect to the exterior walls. The image in the upper-right corner shows a smaller portion of the prism elements and how they connect in the corners.

With COMSOL Multiphysics® version 6.0, it is also possible to specify the total thickness of the boundary layer elements. This gives more flexibility in the specification of the layers; you can enter the total thickness of all layers or the thickness of the first layer.

Mesh Plot Coloring Improvements

The new color table called Traffic Flow is designed to highlight elements of poor quality more clearly, and it is the default color table when you add a Mesh plot. The color table benefits people with color vision deficiency.

A model with mesh elements in the Traffic Flow color table.
The new default color table, Traffic Flow, makes it easier to locate mesh elements with low quality.

COMSOL Multiphysics® version 6.0 also comes with the possibility to color elements by their type in a mesh plot. You can use this new coloring option together with filtering to inspect the mesh elements inside domains in 3D, as illustrated in the figure.

A sports car model surrounded with a mesh plot with three element types in green, yellow, and magenta.
A mesh plot of the mesh used for the simulation of the flow field around a sports car. The elements are colored by their type (green for tetrahedrons, yellow for prisms, and magenta for pyramids) and are filtered with a logical expression to see the elements inside the air domain.

Information About the Mesh Build

Some warnings that may appear when running mesh operations have been converted into Information nodes to better indicate the severity of the feedback. For all Information, Warning, and Error nodes that contain coordinates, you can now easily zoom and clip around the coordinates with dedicated buttons in the Settings window for these nodes. This makes it easier to closely inspect the region of the geometry featured in the feedback from the mesher.

An Information node with a coordinate specification locating an element of low quality. The new option to clip around the coordinates makes it easier to inspect the problematic region.

A new Information section is added to the Settings windows for all mesh operations. When the operation is built, this section displays the build time, build version, and other information.

More Efficient Mesh Copying

In the case of several similar connected components of entities, it is now possible to use only one Copy operation to copy the mesh from one component to the other components. In the example shown below, each copper coil consists of four domains and defines a connected component. The improved mesh copy makes it straightforward to copy the mesh from one coil to all the other coils in the geometry.

Two motor models with copper coils showing the mesh.
Mesh copying from 4 source domains (the coil in the front) to 28 destination domains, defining 7 connected components, using one copy operation.

Physics-Controlled Meshing for Pressure Acoustics

Physics-controlled meshing is now supported for the Pressure Acoustics, Frequency Domain and Pressure Acoustics, Transient interfaces. This automatically gives suitable mesh size for the current wavelength, structured mesh in perfectly matched layers (PML), mesh copying for boundaries with applied periodic conditions, and boundary layer mesh for Exterior Field calculations.

The COMSOL Multiphysics UI showing the Model Builder with the Mesh node highlighted, the corresponding Settings window, and an ear bud model in the Graphics window.
Model of an ear bud where the element size is automatically determined to resolve the wavelength, and a structured mesh is automatically built in the PML domains. There is also a thin boundary layer closest to the tetrahedral mesh to resolve the exterior field calculation. The mesh elements are colored by their type.

Updated Tutorial Model

COMSOL Multiphysics® version 6.0 brings an updated meshing tutorial model.

Remeshing an Imported Mesh Without Generating a Geometry

An imported vertebra model with a teal block mesh.
Meshing tutorial demonstrating how to combine an imported STL mesh with a block. The simulation mesh is generated without creating a geometry from the mesh.

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