Trelis Overview


Advanced Meshing for Challenging Simulation

Trelis is a high-end, commercial-grade pre-processor for complex FEA and CFD simulation. It is based on the time-proven CUBIT™ software from Sandia National Laboratories. For more than two decades, csimsoft and Sandia have co-developed CUBIT to do Sandia's really challenging simulation. Now, commercial and academic users can use the tool for their tough simulation problems.

Three versions of Trelis.

Because CFD and FEA needs are different, csimsoft offers three Trelis versions:


Trelis FEA has features and mesh schemes specifically designed to meet the needs of FEA users. Trelis CFD includes powerful tools and boundary layer features for doing difficult CFD simulation. Trelis Pro combines all the features of Trelis FEA and Trelis CFD into one robust package.

Compare versions

Trelis features.

Trelis raises the standard for FEA and CFD pre-processing. Companies worldwide realize how critical mesh generation is to FEA and CFD analysis. Our customers use Trelis to get high-quality meshes that give them the very best results. Here are some of the reasons why people are using Trelis for challenging simulation.

ITEM Wizard

Immersive Topology Environment for Meshing (ITEM) is a wizard-like tool that walks users through the meshing process. It uses Trelis's power tools for easy geometry cleanup and for generating the best possible mesh. The ITEM process includes:

  • Import/Create Geometry
  • Setup Mesh Parameters
  • Prepare Geometry
  • Mesh the Model
  • Validate Mesh Quality
  • Define Boundary Conditions
  • Export the Mesh

ITEM Watch the video on how to use ITEM

Geometry Creation

Engineers spend up to 65% or more of their time preparing geometry for meshing. Trelis has powerful tools for easier clean up and defeaturing so that you can spend more time with the results.

There are three primary ways of creating geometry for meshing in Trelis.

  • Geometry primitives for building models
  • "Bottom up" geometry from vertex, curves, and surfaces
  • CAD files imported from another application

Trelis supports many common CAD formats. See Trelis Data Translators for more information about supported file formats.

Geometry Transforms

Geometric entities can be modified in Trelis using transform operations, which include align, copy, move, reflect, restore, rotate, and scale.

Boolean Operations

Trelis supports powerful boolean operations to intersect, subtract, and unite geometric entities.


Geometry decomposition is often required to generate an all-hexahedral mesh for three-dimensional solids. "Web cutting" is cutting an existing body into two or more pieces through the use of a cutting tool. Trelis has several methods for making web cuts.

ITEM Watch our tutorials and vidoes on using Trelis's tool to decompose models for meshing.

Cleanup and Defeaturing

Sometimes models imported from a CAD program will either provide too much detail for mesh generation or the geometry is deficient. This can be corrected by making changes to the model. Trelis has excellent tools for cleanup and defeaturing including.

  • Healing
  • Tweaking Geometry
  • Removing Geometric Features
  • Automatic Geometry Clean-up
  • Regularizing Geometry
  • Finding Surface Overlap
  • Validating Geometry
  • Debugging Geometry
  • Trimming and Extending Curves
  • Stitching Sheet Bodies
  • Defeaturing Tool
  • ...and many more

Power Tools

Trelis's Power Tools help users to identify problems with geometry before meshing and recommend solutions for getting it ready for meshing. After a mesh is generated, additional Power Tools check the mesh quality based on various metrics and values the user specifies.

  • Geometry Tree
  • Diagnose Geometry
  • Defeature Geometry
  • Diagnose Meshability
  • Diagnose Mesh Quality
  • ITEM
Geometry Tree

The Geometry Tree power tool contains a hierarchy of all the entities in the model. It includes boundary conditions, groups, geometry entities, and boundary layers. Selecting an entity in the tree will select the same entity in the graphics window. The geometry tree's context menu is sensitive to the type of item and the number of items selected.

Diagnose Geometry and Defeature Geometry

The Diagnose Geometry and Defeature Geometry power tools contain diagnostics and tools for analyzing, identifying, and repairing geometry.

Diagnose Meshability and Diagnose Mesh Quality

The Diagnose Meshability power tool can be used to ascertain the meshability of the model. Trelis can check a model and identify which surfaces or volumes are not meshable and offer solutions for fixing the problem. After the mesh has been generated, the Diagnose Mesh Quality power tool can perform element quality checks. These checks will warn users of any elements that are below a default or user-specified threshold, allowing various visualization options for displaying element quality. If the current element quality is unacceptable, Trelis can present several possible mesh improvement solutions.

Scripting, Journal Files, and Parameterization

Trelis utilizes a rich command language that can be stored as a journal file. These scripts can be used to parameterize the construction of models to determine design sensitivity and to capture repetitive meshing processes.

Trelis commands can be saved in journal files that can be reused and shared. These journal files can be used to automate specific tasks or the entire meshing process. Trelis also has the ability to interpret Python scripts, giving users the full capability of the Python scripting language.

The Trelis GUI commands are automatically saved to an external temporary journal file on the user's hard drive and in the History window. Reviewing these commands is a great way to become familiar with Trelis's command language. Journal files can be created and played to reproduce a part of or the entire process of building an analysis model.

Journal Files Watch the video on how to use journal files

Trelis gives users the ability to parameterize the construction of the model and evaluate design sensitivity. Parameters representing dimensions of objects may be defined in the script and easily adjusted to modify the geometry.

Learn More Watch the webinar: Customizaton and Scripting with CUBIT (41:05 minutes)

Boundary Conditions

Trelis support the application of boundary conditions to sidesets, nodesets, element blocks, and to geometric entities. Trelis FEA and Trelis CFD support a variety of FEA and CFD boundary conditions, respectively. Trelis Pro supports both FEA and CFD boundary conditions.

Supported File Format

Meshes generated with Trelis are exported with specified boundary conditions to many standard FEA and CFD formats. If Trelis doesn't support a particular file format, Trelis's public mesh export API allows users to write their own exporter for any file format.

Learn More Learn more about supported formats

Customizable Components

Trelis users use the CubitInterface API (C++ and Python) to extend Trelis by building custom components that are focused on solving a specific problem or type of problem. Trelis's GUI components are extensible and modifiable so users can customize the interface to suite their needs.

Learn More Watch the webinar: Developing CUBIT Components (27:15 minutes)

Intuitive Environment

Trelis includes both a convenient command line interface with an extensive command language as well as a polished graphical user interface environment.

CubitInterface API Watch the Overview video to learn more about the Trelis GUI

CUBIT and Trelis.

For decades, our team has worked with Sandia National Laboratories to develop the CUBIT Geometry and Mesh Generation Toolkit. Sandia distributes CUBIT to U.S. government entities and asked csimsoft to handle licenses to non-government users. Trelis is CUBIT for commercial and academic users. Over the years, we've added additional features and provided timely maintenance updates for non-government users.

Many companies, universities, and national labs have developed software that uses the CUBIT format. Trelis supports the CUBIT .cub and .jou files and Python scripting, so you can use Trelis with third-party software just as you would CUBIT.

Have questions about Trelis? Contact csimsoft today.

Try Trelis for yourself.

See for yourself why Trelis is the pre-processor of choice of engineers worldwide. Try Trelis Pro on your own models free for 30 days.