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RTMsim
What RTMsim is
RTMsim is a free desktop application for simulating mould filling in resin transfer moulding. It runs on Windows and Linux, supports offline use, and allows data export. The model represents resin moving through a porous cavity and follows the advancing flow front with a volume-of-fluid equation. Users supply a three-node triangular shell mesh describing the part’s mid-surface; RTMsim does not generate this mesh, so a separate meshing tool is required. Material regions can include preform thickness, porosity, permeability and principal permeability directions, including non-isotropic permeability. Its GUI inspects meshes, starts or continues simulations, supports interactive inlet selection and plots filling and pressure distributions. Tutorials describe cascade injection and validation cases compared with analytical results, ANSYS Fluent and myRTM. Julia package functions permit terminal or programmatic runs, plotting and equation extensions. RTMsim was developed with Julia 1.8, installs through Julia’s package manager and is licensed under GPL-2.0.
Who it suits
It suits mould designers studying inlet and vent placement, filling patterns and filling times. Users should be comfortable preparing compatible triangular meshes separately and using Julia, especially on Linux.
What it does well
- Free plan and offline desktop use
- Windows and Linux support
- Interactive inlet selection and result plots
- Supports non-isotropic permeability
- Julia API enables extensions
What to know first
- Mesh generation is not included
- Linux GUI is experimental
- Headless machines are unsupported
- Coarse meshes can cause filling-time error
Verdict
RTMsim combines a focused RTM filling model with GUI and Julia workflows. It is most suitable when you can prepare the required mesh and accept the documented Linux and headless limitations.
Facts from RTMsim's own pages
- Command line and API
- After installing the Julia package, users can run simulations and access RTMsim functions without using the GUI. · obertscheiderfhwn.github.io, 11 Oct 2026
- Data export
- Yes · obertscheiderfhwn.github.io, 24 Sept 2026
- Delivery mode
- desktop · obertscheiderfhwn.github.io, 24 Sept 2026
- Extensibility
- Additional equations, such as degree-of-cure modeling, can be added, and existing equations can be modified for cases such as variable cavity thickness. · obertscheiderfhwn.github.io, 12 Oct 2026
- Free plan
- Yes · obertscheiderfhwn.github.io, 24 Sept 2026
- GUI
- The GUI can start and continue simulations, inspect meshes and plot filling and pressure distributions. · obertscheiderfhwn.github.io, 11 Oct 2026
- Headless limitation
- The repository README says running RTMsim on headless machines is currently unsupported due to package GLMakie issues. · github.com, 12 Oct 2026
- Inlet selection
- Users can select inlet ports interactively, and the tutorials describe cascade injection using additional inlet ports. · obertscheiderfhwn.github.io, 11 Oct 2026
- Installation requirement
- RTMsim was developed and tested with Julia 1.8 and is installed through Julia’s package manager from its GitHub repository. · obertscheiderfhwn.github.io, 12 Oct 2026
- Intended users
- The documentation describes using filling simulations during mould design to study inlet and vent placement and avoid incomplete filling or trapped air. · obertscheiderfhwn.github.io, 12 Oct 2026
- Interface and plotting
- The GUI supports mesh inspection, simulation start and continuation, interactive inlet selection, and plots of filling and pressure results. · obertscheiderfhwn.github.io, 12 Oct 2026
- License
- The public repository identifies RTMsim as licensed under GPL-2.0. · github.com, 12 Oct 2026
- Linux limitation
- The Linux GUI is described as experimental, and the documented Linux workflow runs simulations from the Julia terminal. · obertscheiderfhwn.github.io, 12 Oct 2026
- Linux support
- The Linux GUI is described as experimental; the guide documents running simulations from the Julia terminal. · obertscheiderfhwn.github.io, 11 Oct 2026
- Material properties
- Users can specify preform thickness, porosity, permeability and principal permeability directions for multiple regions. · obertscheiderfhwn.github.io, 11 Oct 2026
- Mesh accuracy
- The documentation says a mesh refinement study is needed because coarse meshes can predict filling time with an error of approximately 20% in the described case. · obertscheiderfhwn.github.io, 11 Oct 2026
- Mesh input
- The simulation uses a three-node triangular shell mesh on the part’s mid-surface, which must be generated with a separate meshing tool. · obertscheiderfhwn.github.io, 11 Oct 2026
- Mesh limitation
- RTMsim does not include mesh generation; a compatible triangular shell mesh with predefined regions must be prepared separately. · obertscheiderfhwn.github.io, 11 Oct 2026
- Model capabilities
- The documentation says the model targets accurate filling patterns and filling times and supports non-isotropic preform permeability. · obertscheiderfhwn.github.io, 12 Oct 2026
- Offline access
- Yes · obertscheiderfhwn.github.io, 24 Sept 2026
- Programming interface
- The installed package exposes functions for running simulations and plotting meshes, sets, and results without using the GUI. · obertscheiderfhwn.github.io, 12 Oct 2026
- Purpose
- RTMsim is a Julia module for simulating resin transfer mould filling. · obertscheiderfhwn.github.io, 12 Oct 2026
- Simulation inputs
- The model uses a triangular shell mesh of the part’s mid-surface, with cell sets for injection ports and regions with differing preform thickness, porosity, and permeability. · obertscheiderfhwn.github.io, 12 Oct 2026
- Simulation model
- The model simulates flow through a porous cavity and tracks the flow front using a volume-of-fluid equation. · obertscheiderfhwn.github.io, 11 Oct 2026
Where RTMsim stands on Freedom251
- Physics Simulation Software#54 of 89