Geometry has central role in setting up multiphysics simulations, said Lorant Olasz, Comsol’s technical product manager working with CAD.
He spoke earlier this month at the Comsol Conference held in Boston. Comsol makes Multiphysics modeling software.
The software contains two engines for creating and managing geometry: the native geometric kernel that’s part of the basic package, and then a CAD import module for, as the name implies, directly importing CAD geometry. The former kernel allows users to create their own geometry within the multiphysics package.
Regardless of how you get CAD into the software, “you must set up the geometry inside the software to work with the geometry,” he said. “When selecting the physical phenomenon you want to apply, you select geometry for forces to apply it. You need to make sure all the different domains are meshed properly.”
Users can even apply different materials to different parts of the model.
Both CAD import and the CAD design kernel allow users to import and then repair geometries, “and if you’re using the design kernel you have a few extra g operations like fillets or the option to thicken the surface of a solid,” he said.
The CAD Import Module supports the import of a variety of different file formats including the Parasolid and ACIS formats, and standard formats like STEP and IGES. Users import their files by saving them in any of these formats. The import module also allows users to import the native file formats of a number of CAD systems, such as Inventor, Creo Parametric, and SOLIDWORKS. The optional file import for Catia V5 provides support for importing the native file format for this system.
All imported CAD files are automatically converted to a Parasolid geometry, using the Parasolid geometry engine that is included with the module.
The native CAD kernel offers a solution for geometry not created inside Comsol, he said. It also provides a lot of functionality for geometrical operations, including extra functions that don’t exist within the CAD import module.
When importing, it’s possible to change the geometrical representations, or one of the settings of geometry nodes, “But it’s generally not something you have to think a great deal about,” Olasz told attendees to his workshop, which was part of the conference.
“The native geometry kernel isn’t a CAD software, of course, he said. “We’re not creating geometrical models for manufacturability. But you can actually create pretty much the same things as you would in a CAD software package. Perhaps it’s not the most advanced geometrical forms, of course, but in general whatever you’d like to model in CAD you can draw it in the native kernel nowadays.”
After setting up the geometry and ensuring it’s correct, the user can then leave that geometrical mode to apply physical forces to the model or to mesh the model, he added.
A “form union” step brings all the geometries together into one object, Olasz said. “So you have one object with several domains.”
Or, users could choose the “form assembly’ function for objects that should be treated separately, such as parts that move in relation to one another.
Either way, “this creates the final object that will be seen by the physics or the mesher,” Olasz said.
