Welcome to Part 3 of my Computational Fluid Dynamics (CFD) fundamentals course! In this course, the concepts, derivations and examples from Part 1 and Part 2 are extended to look at unstructured meshes and mesh quality metrics (aspect ratio, non-orthogonality, skewness and Jacobian Determinant). The course starts from first principles and you will rapidly develop a working CFD solution using the Excel sheets and Python source code provided. By the end of the course, you will understand how the CFD equations are discretised for unstructured meshes. This discretisation approach is a natural extension of the discretisation approach that is adopted for structured meshes (which were considered in Part 1 and Part 2). CFD codes which are constructed in this unstructured way (such as ANSYS Fluent, OpenFOAM, Star CCM, Saturne) can handle cells of any size and shape. You will learn about the main quality metrics (aspect ratio, non-orthogonality, skewness, Jacobian Determinant) that are used to assess these meshes, how they are calculated and what they actually mean. For this course, no prior experience is required and no specific CFD code/coding experience is required!  You do not need ANSYS Fluent, OpenFOAM, Star CCM or any other CFD code to use this course.