Fluid Dynamic Software (free)

Free fluid simulation enginees:

GFSSP is a general-purpose computer program for analyzing steady state and time-dependent flowrate, pressure, temperature and concentrations in a complex flow network.
https://www.nasa.gov/gfssp

Blender. Visual FX, Fluid physics are used to simulate physical properties of liquids especially water.
https://docs.blender.org/manual/en/latest/physics/fluid/introduction.html

OpenFOAM has an extensive range of features to solve anything from complex fluid flows involving chemical reactions, turbulence and heat transfer, to acoustics, solid mechanics and electromagnetics.
https://openfoam.com/

Advanced Simulation Library (ASL) is a free and open source hardware accelerated multiphysics simulation platform
http://asl.org.il/

Elmer is an open source multiphysical simulation software mainly developed by CSC - IT Center for Science (CSC).
https://www.csc.fi/web/elmer

Find a detailed description of the code philosophy, components, and implementations in the SU2 AIAA Journal article. Whether it's discrete adjoints, non-ideal compressible CFD, high-performance computing, or incompressible flows with heat transfer, SU2 has something for you.
**** https://su2code.github.io/