Software

Numerous software are available for performing CFD simulations. They differ, for example, in the numerical methods they employ, the physical models available, whether or not the source code can be accessed and modified, and their ease of use.

This page reviews the various software packages used at OptiFluides. Note that there are many others, and that this list is far from exhaustive.

1. ANSYS Fluent

• General: ANSYS Fluent is the most widely used CFD software in industry. Its versatility and robustness make it an extremely powerful tool for modeling a wide range of physical phenomena and therefore industrial problems. Aerodynamics, heat transfer, multiphase or reactive flows, aeroacoustics, rotating machines, with of course a wide choice of turbulence models, ANSYS Fluent remains the most widely used tool at OptiFluides.
• Advantages: Precision and versatility, large library of physical models, parallelization possible on CPUs and, progressively, on GPUs, user-friendly interface, pre-processing, meshing and post-processing integrated into the software suite. Another advantage is its widespread use, so that it remains a validated “gold standard” for many industries.
• Drawbacks: Very high cost, learning curve requiring support for novice users, editor’s opacity on certain numerical methods and physical models.
• Target audience: Any company/laboratory looking for a versatile, reliable software package that has been widely validated in industry, while maintaining a reasonable budget.

2. OpenFOAM

• General: OpenFOAM (Open Field Operation and Manipulation) is an open-source software suite, widely used in academic research and industry. It offers a wide range of solvers for fluid flow, heat transfer and other physical processes. In a way, it’s the free counterpart to Fluent. 
• Advantages: Free access, extremely flexible and customizable, supported by a large community of developers. Direct access to code. Enables a large number of calculations to be carried out simultaneously or over long periods of time without licensing problems.
• Drawbacks : The lack of a user-friendly graphical interface can make it difficult for beginners to use. Set-up time can be lengthy, requiring in-depth knowledge of programming and fluid mechanics. Once you’ve mastered the logic of programming models, this disadvantage becomes an advantage, making it easy to script a large number of cases and carry out complex parametric studies in a very short space of time.
• Target audience: Researchers and engineers with solid experience in numerical simulation and code development.

3. STAR-CCM+

• General: Developed by Siemens, STAR-CCM+ is a well-known CFD software, based like its predecessors on the finite volume method. Less established than ANSYS Fluent on the market, it is nevertheless an equally reliable and versatile commercial software, well suited to use in industry and research. 
• Advantages: Intuitive user interface, precision and versatility, large library of physical models, parallelization on CPUs, pre-processing, meshing and post-processing (including advanced automated and adaptive meshing functionalities). Excellent technical support.
• Drawbacks : High cost, user guidance required for novice users.
• Target audience: Any company/laboratory looking for versatile, reliable and industry-validated software.

   

4. NEK5000

• General: NEK5000 is an open-source software package based on the spectral element method, providing very high accuracy. Originally developed at Argonne National Laboratory, it is mainly used for CFD simulations of complex flows. NEK5000 is an excellent choice for users seeking to solve problems requiring fine, accurate simulations, with total control over numerical parameters. However, its complexity and steep learning curve make it better suited to users with experience in numerical simulation and HPC computing. 
• Advantages: NEK5000 stands out for its very high accuracy and scalability. The spectral element method employed by NEK5000 can solve problems requiring fine resolution of turbulent structures. It is also optimized for complex thermal flows.
• Drawbacks : The interface is not the most user-friendly, and using NEK5000 requires in-depth knowledge of numerical methods and Fortran programming.
• Target audience: Researchers and engineers in advanced fluid dynamics, particularly in the aeronautics, nuclear and fundamental research sectors, with a specialization in high-precision simulations and turbulent flows.

5. Code_Saturne

• General:Developed by EDF (Électricité de France), Code_Saturne is an open-source software package for CFD simulations. It is used in a variety of fields, including energy, industry, the environment and scientific research. Code_Saturne is recognized for its ability to handle complex geometries and multiphase phenomena, with a special focus on industrial applications. 
• Advantages: High capacity for multiphase modeling and management of reactive and turbulent flows. Its modular architecture means it can be integrated with external solvers or coupled with other codes (such as SYRTHES for heat transfer). It is also well optimized for CPU parallelization.
• Drawbacks: Less intuitive user interface than commercial software such as Fluent. Configuration and handling can be complex for beginners, although the community and documentation are well-supported.
• Target audience: Industry and researchers, particularly in the energy and environmental fields (dams, nuclear power plants, thermal installations), as well as engineers specializing in industrial flow simulation.

6. Fire Dynamics Simulator

• General: Fire Dynamics Simulator (FDS) is a CFD software package developed by the National Institute of Standards and Technology (NIST), specifically designed to simulate fire phenomena, such as smoke propagation, heat, and gas behavior in enclosed and open environments. FDS uses an approach based on the Navier-Stokes equations for low-velocity flows, with particular emphasis on combustion processes, thermal radiation and smoke dispersion. 
• Advantages: FDS is optimized for fire and fire safety simulations. It includes sophisticated combustion, heat release and radiative heat transfer models, as well as specific options for modeling ventilation and extinguishing systems. Its compatibility with Smokeview, a visual post-processing software, enables the generation of highly detailed graphical representations and animations of fire and smoke evolution.
• Drawbacks: FDS is particularly specialized in fire simulations, which makes it less flexible than other general-purpose CFD software for applications outside the fire domain. Users must have a good knowledge of combustion and fire safety principles to take full advantage of its features. Options for simulating complex (non-combustion) flows are more limited than in software such as ANSYS Fluent or Star-CCM+.
• Target audience: Fire safety engineers, architects and researchers in the fields of fire protection and risk management.

7. TELEMAC

• General:TELEMAC is a set of open-source numerical simulation modules developed by the Laboratoire National d’Hydraulique et Environnement (LNHE). It is specifically designed for hydraulic simulations and modeling of free-surface flows, such as rivers, estuaries, coastal and marine areas. Main modules include TELEMAC-2D for 2D flows, TELEMAC-3D for 3D flows and TOMAWAC for surface wave simulations.
• Advantages: Specialization in the simulation of free-surface flows, including the effects of tides, waves and sediments. Widely used for hydraulic modeling of large infrastructures, such as dams and port facilities. The software is well suited to environmental analyses, thanks to its ability to model complex phenomena related to sedimentation, water quality and interactions between water and structures.
• Drawbacks: Less suited to compressible flows or conventional industrial applications. Technical handling, although documentation is provided and a large community is active.
• Target audience: Hydrologists, civil and environmental engineers working on hydraulic engineering projects. Particularly useful for government agencies and engineering companies working in the field of water management.

Conclusion

The choice of CFD software largely depends on the user’s specific needs, level of expertise and available budget. Among the software used by OptiFluides, ANSYS Fluent (and STAR-CCM+) are often preferred for their advanced capabilities and ease of implementation, but their cost and licensing system represent a major brake on wider use. OpenFOAM, which we are using more and more, offers unrivalled flexibility thanks to its open-source nature, and requires code development skills. For very specific applications, other codes such as NEK5000 and TELEMAC may prove more suitable.