Dear Lukas, it depends from physical model which you want consider; in the case of non rotating flow, Fluent and Comsol-Multiphysics can be good choices, in the case of rotating flow (e.g. pumps and fans simulation) in my experience CFX is better. Gianluca
Generally, the best program to modeling a fluid problem is Fluent due to its accurate results. However, CFX present a good agreement for the rotational problems (For example; turbo, vortex …).
OpenFOAM - I currently use several of its branches such as foam-extend and OpenFOAM+: they are robust and efficient for several applications (especially, incompressible flows) and, for me the most important, open-source. But as stated above, it depends a lot on your problem. For a survey on the most used CFD software, check the link: https://www.resolvedanalytics.com/theflux/comparing-popular-cfd-software-packages
it depends on what your cases that you would like to simulate. According to my knowledge regarding thermal case studies, i believe that ANSYS FLUENT is better for the simulation of Aerodynamics subject as well as to others fluid mechanics and heat transfer subjects such as ventilation, natural convection, combustion ect... but for turbomachinery simulation i think ANSYS CFX is better than ANSYS FLUENT. COMSOL is also favourite by me and i used it now for simulation of some heat transfer cases. however, if the good experiments and instruments such high speed camera, thermal camera, PIV are combined with ANSYS FLUENT, you will have an excellent work. so that i prefer in this cases ANSYS FLEUNT
It possesses a wide range of models to approximate the Navier-Stokes equations together with different meshing schemes. Also it is more efficient in terms of time required to run a simulation.
Each CFD code can have some specific appealing features, depending on both the flow problem and physical model. We tested several CFD codes for this turbulence flow problem:
Conference Paper A comparative test for assessing the performances of large-e...
Clearly ANSYS CFX - because of its proven accuracy for many flow physics (thoroughly validated code), its numerical robustness and the usually obtained speed to solution. Further I appreciate a lot the customization features of ANSYS CFX through its easy and intuitive to use CCL language. Flexible to be used in both GUI and command line mode, fully scriptable for automation of simulations.