Which CFD package is appropriate for your organization?

Due to my theoretical and practical experience in Computational Fluid Dynamics (CFD) I was asked to investigate and select a proper CFD package for our R&D group. I actually find it useful to summarize and share it here. 

There are basically four main groups available when one wants to select a CFD package:

• Group 1: Commercial professional CFD packages (e.g. ANSYS Fluent, Star-CCM+, FloTHERM)
• Group 2: Commercial CFD add-ins embedded in existing CAD software (e.g. SolidWorks Flow Simulation, FloEFD)
• Group 3: Open source CFD software with commercial GUI (e.g. OpenFOAM/Visual-CFD, OpenFOAM/ANSA-µETA post-processor)
• Group 4: Open source CFD package (e.g. OpenFOAM/Paraview)

Group 1 as one can see includes some famous CFD software. They are very powerful and can model different types of simple and complicated fluid/thermal assignments (either generalized e.g. ANSYS Fluent and Star-CCM+ or specialized e.g. FloTHERM for electronic cooling). Furthermore, one has a very good control on important issues such as surface and volume mesh generation while pre-processing. They also normally offer good customer supports. However, generally some modification on imported CADs is required during pre-processing. Moreover, the license fee is quite costly and users need some sort of CFD knowledge and training to work with them.

Group 2 has the main benefits in its ability to be simply embedded in existence CAD software. They are also very easy to be used and require only few CFD knowledge and training. However, one can’t have full control on pre-processing e.g. on mesh generation. Basically these software are appropriate for less complicated physical assignments compared to group 1. Particularly when people do not have enough time and competence in their organization and only wants to perform CFD assignments occasionally, this group is a very good candidate. License fee is also much cheaper than the former group.

Group 3 in many cases is as good as group 1 particularly in common single phase flow assignments. However, for problems with complicated physics (e.g. two phase flow) it might be time consuming to develop simulations in open source codes with accurate results. As the name shows there is no license fee for open source software (e.g. OpenFOAM); however, some license fee is needed for commercial GUI. These GUI software are normally used to make the tedious time consuming work with text interface in open source codes quicker and far easier during pre-processing. On the other hand one can run a CFD simulation in open source codes even without any GUI (Group 4), but it takes longer to set up pre-processing specially for beginners. 

Group 4 is similar to group 3; however, no GUI is used for pre-processing. Furthermore, there is absolutely no license fee for the package. It should be added that pre-processing in open source codes is time consuming specially for beginners. Furthermore, some training and even some consultancy support from experienced users might be required at the beginning to employ this option effectively. This is the most cost effective solution in long run specially when only small variations in geometrical topology is required and same type of physics is modelling.

The below table summarizes the most important parameters differentiating the above four groups.

As you see there is no definite answer to the question “which CFD package is appropriate for your organization?”. It is totally dependent on your organization's requirements, resources, available time, competence and other factors. However, I believe the above short note can shed some light in the process for people who are investigating to select a proper CFD package.

At the end please remember this tip: 

“Nobody trusts a computer simulation except the guy who did it, and everybody trusts experimental data except the guy who did it”!!!

Actually CFD and experiments always must be used to support each other in different stages of product development. Please remember that at the end we always need to make a full scale prototype and perform experiments on the worst case scenarios, which is actually necessary before lunching our products! CFD is just a tool to help us to make this process quicker, cheaper and more effective.