Geometry and Mesh Updates
COMSOL Multiphysics® version 5.3a brings several geometry and mesh updates, including expanded functionality for removing thin domains, a new option for defining a size expression using predefined variables, and more. View all of the geometry and mesh updates below.
Automatic Removal of Thin Domains
The Remove Details operation has expanded functionality to remove thin domains from your geometry. By making sure that the Thin domains check box is selected (it is selected by default), located in the Details to Remove section, the operation will find and remove any thin domains from your geometry automatically.

Size Expression Edit Field for Element Size
There is a new option in the Size Expression node that allows you to define a size expression using variables defined in physics, materials, and settings made in the study, such as a frequency. The ability to include variables in the Size expression edit field to define the expression enables more customized meshes that can update as changes are made in other parts of the model. The evaluation context is the same as when running "Get Initial Value for Step" on the specified study step.
Selections in Mesh File Format
The COMSOL mesh file format (.mphbin and .mphtxt) now supports selections associated with the file. This makes it possible to transfer information on selections together with the mesh when importing from third-party software. These selections will be available for use when specifying materials, physics, etc. Correspondingly, when exporting a mesh from the COMSOL Multiphysics® software to a COMSOL mesh file, you can choose to export the selections of the corresponding component.
Isolated Entities in Mapped Meshes
The mapped mesh feature can now handle isolated vertices and edges that exist within 2D domains and 3D faces. This makes it possible to generate structured meshes without needing to partition the geometry before meshing.