1. #### GRID / MESH A **mesh** divides a geometry into many elements. These are used by the CFD solver to construct **control volumes**. **Terminology:** • Cell = control volume into which domain is broken up. • Node = grid point. • Cell centre = centre of a cell. • Edge = boundary of a face. • Face = boundary of a cell. • Zone = grouping of nodes, faces, cells • Domain = group of node, face and cell zones.  Points to consider when generating a mesh are: • Mesh resolution • Type of mesh • Computer resources The **shapes of control volumes** depend on the** capabilities of the solver**. - Structured-grid codes use quadrilaterals in 2D and hexahedrons in 3D flows. - Unstructured-grid solvers often use triangles (2D) or tetrahedron (3D), but newer codes can use arbitrary polyhedrons.  2. #### Grid Structure The purpose of the mesh generator is to decompose the flow domain into control volumes. The primary outputs are: • cell vertices • connectivity information Precisely where the _nodes_ are relative to the vertices depends on whether the solver uses, for example, cell-centred or cell-vertex storage. Further complexity is introduced if a staggered velocity grid is employed.  3. #### Grid Types - Structured Grids - Cartesian - Curvilinear  4. #### Block-structured Grids a) Matching b) Non-matching c) Chimera (composite)   Generally, multiple blocks are useful in maintaining a structured grid configuration around complex boundaries. - generally desirable to avoid sharp changes in grid direction (which lead to lower accuracy) in important and rapidly changing regions of the flow, such as near solid boundaries. - One should also strive to minimise the non-orthogonality of the grid. https://www.manchestercfd.co.uk/post/all-there-is-to-know-about-different-mesh-types-in-cfd #CFD