What is OpenFOAM and CFD?

OpenFOAM (Open source Field Operation And Manipulation) is a free/libre and open source toolbox which is used in academia and industry to solve continuum mechanics problems, including Computational Fluid Dynamics (CFD). CFD is a branch of fluid mechanics that uses numerical analysis and data structures to solve and analyse problems that involve fluid flow

You can learn OpenFOAM through Spoken Tutorials.