A Comparison of CFD Software Packages
The website CFD-Online lists over 200 CFD related software packages, with new packages coming online monthly claiming capability and performance improvements over established packages. Such a variety can be a little overwhelming for those of you who are trying to identify which is the right tool for the job. That is why we've written this review based on first hand experience with many of the codes discussed here and our impression of capabilities based on our research where we don't have first hand experience.
CFD software packages fall into one of the following five broad categories, more-or-less;
Open-Source: Open-source software is provided under a software license that permits users to study, change, and improve the software. Such a license structure generally ensure that the software remains free of cost and retains a wide audience and developer base.
The most widely used general purpose open-source CFD software package is known as OpenFOAM. While the official OpenFOAM release is maintained by the OpenFOAM Foundation, a few splinter cell groups have broken off with code variations in order to commercialize some aspect of their additions to the code, typically through consulting. The major flavors include blueCFD-core and openFOAM+. There is a big dropoff in usage to other free codes such as Stanford University’s SU2 and the Lattice-Boltzmann solver Palabos.
The lead arguments for the adoption of open-source are the following. It is freely licensed, making it increasingly cost effective as your demand increases. If it is a widely distributed code it will be reliable and accurate as a result of being scrutinized and improved by a large group of diverse developers all motivated to ensure that the code performs well. In addition, if a user has the skill and desire they can add functionality through additional coding. The major arguments against open-source are the limited user-support, increased cost of ownership relating to reduced usability, the lack of specialized capabilities, and the requirement of additional software, such as pre- and post-processors.
Open Source wrappers: In order to make open-source more user friendly developers have wrapped codes such as Open-FOAM into more user friendly GUI environments bundled with additional software such as pre- and post-processors. Examples are Visual-CFD, HELYX and simFlow. An interesting recent twist on this concept is that of web browser based simulation, as provided, for example, by SimScale. Wrappers do provide the convenience of a single interface, but suffer from the fact that the platform is an additional level of separation between the user and the execution code. The obvious arguments for adopting a wrapper platform is that they can provide some of the convenience of a full-service commercial platform with a much lower price. The arguments against wrapper platforms are that they don’t overcome some of the key limitations of open-source, i.e. limited user-support and lack of specialized capabilities, while adding another level of software with its own potential for bugs and which may be poorly supported and developed in its own right.
CAD integrated: The most widely used CFD platforms are the SolidWorks and Autodesk Inventor CFD add-ons integrated within those native 3-D solid modeling platforms. This type of CFD package is marketed to product designers who are primarily seeking to solve steady-state, single-phase, non-reacting flow problems and with a focus on ease of use. These packages typically include native meshing and post-processing tools. Conjugate heat transfer, fluid-structure interactions, chemical reactions, multiphase flows and other high-end capabilities are typically out of reach for these packages.
Specialty: Meanwhile, there are many codes that are targeted to niche markets with specialized functionality. CONVERGE is a multipurpose code with a high level of sophistication with regards to moving meshes, multiphase flows and turbulent combustion as needed for their focus on the automotive, internal combustion market segment. AVL Fire is similarly focused on the automotive engine market. Other heavily targeted platforms include the FloTHERM suite targeting the electronics industry, FINE/Marine for marine applications, 6Sigma for data center ventilation, EXA for external aerodynamics, XFlowCFD for Lattice-Boltazman simulations, SPH-flow for smoothed particle hydrodynamics simulations, CPFD for fluidized bed reactors, and CFX for turbomachinery, among many others. A relative newcomer is EXN/Aero with its focus on improving performance on very large scale simulations through the combined use of CPU and GPU processing. These platforms can be cost effective if you can match their capabilities to your needs with a high level of confidence.
Comprehensive Packages: For many years, the gold standards in CFD simulation have been Fluent and Star-CCM+ and they are both excellent and diverse tools. Fluent seems to capture more market share in electronic and industrial product markets and Star-CCM+ in the aerospace, automotive and energy industries. COMSOL’s CFD Module and Altair’s AcuSolve are less widely used and are components of broader multiphysics simulation platforms. Never-the-less, they have quickly grown in scope with additional capabilities that are now approaching those of the big two. All four come equipped with meshing and post-processing capabilities and can input from, and output to, all of the popular filetypes and formats. The primary drawback to these packages is their price tag.
CFD packages are relatively inexpensive compared to the personnel costs required to maintain and utilize them. The relative cost difference between commercial and open-source packages are also small and are typically outweighed by the increased overhead needed to setup and interface with open-source software (and the Linux based hardware typically required). The relative cost savings of the CAD integrated package are minimal and such packages are mostly applicable where product designers prefer to have CFD capability natively integrated within the CAD framework. For more on the costs of these software packages, please download our free Ebook on the "Costs of CFD".
In 2016 we took an informal poll of our colleagues preferred software package. The results are shown in the figure on the left. We plan to update this survey in 2017 with a more thorough treatment including industry-by-industry preferences. Stay tuned.