1. OpenFOAM-4.x installation guide:

    Installation/Linux/OpenFOAM-4.x/Ubuntu

  2. OpenFOAM shell commands and advanced use:

    Installation/Working with the Shell

  3. OpenFOAM wiki : Link to lot of OpenFOAM resources

    OpenFOAMWiki

  4. Building a solver from scratch:

    programming_scratch_app.pdf

  5. Chalmers university OpenFoam course material. very good.

    PhD course in CFD with OpenSource software, Quarter 2, 2008

  6. Syntaxes of functions and expressions in OpenFOAM like exp, sqrt. pos(x), etc.

    OpenFOAM

  7. Lot of great OpenFOAM CFD tutorials, book, videos, etc.

    Basic tutorial and even written text guide is very good. well organised content. Holzmann has also written a book on OpenOFAM.

    Numerical Solutions - OpenFOAM Knowledge Base

  8. Resources by OpenFOAM Foundation: Includes C++ source guide, technical guide, training and user guide.

    C++ source guide is the most imp thing here.

    OpenFOAM Resources - OpenFOAM

  9. Basic essential Linux commands you should know to better use OpenFOAM:

    OpenFOAM Linux Guide - CFD Direct

  10. Accessing mesh info:

    How to get mesh information in OpenFOAM?

  11. Matrices in OpenFOAM:

    OpenFOAM guide/Matrices in OpenFOAM

  12. Introductory C++ for OpenFOAM:

    Introductory C++ for OpenFoam Users

  13. OpenFOAM and C++ coding style guide:

    [Coding Style Guide OpenFOAM](https://openfoam.org/dev/coding-style-guide/)

    theodoreOnzGit/C-_YouTube_OpenFoam

  14. OpenFOAM bash commands:

    OpenFOAM Bash

  15. Solvers related study material

    Tim Behrens-OpenFOAM basic solvers for linear systems of equations-slides.pdf

    Tim Behrens-OpenFOAM basic solvers for linear systems of equations.pdf