**Basic Geometric Requirements**

A volume of fluid description of a problem allows algorithms to be formulated with only the following geometric information:

- Volume fractions
- Area Fractions
- Centers of volume and area.

**Simple VoF**

We describe the geometry with a connectivity graph with the associated geometric information given above. The image below is an embedded boundary cell. The grey area represents

the region excluded from the solution domain and the arrows represent fluxes.

**Graph Description**

The graph information for an airfoil would look like this.; Note that not all cells are single-valued:

**Complexity**

In fact, graph information can get arbitrarily complex. Here is a cartoon of an under-resolved geometry and its very complex graph: