Are there libraries for conducting parallel AMR on an unstructured grid ? For a finite volume code, polyhedral cells with arbitrarily shaped faces are as easy to handle as hexahedra, and infact maybe better for AMR because one doesn't have to do anything special for the refined grid. Due to the lack of libraries, I am trying to do this from scratch by splitting polyhedral cells into pyramids with apex at the centre of the polyhedron. For this purpose, each face is first split into quads to form bases of the pyramids. If the polyhedron happens to be a hexahedron, I merge some of the pyramids (three to be precise) back to get the well known 1 to 8 split for hexahedron.
I am not yet into coding the coarsening stage but I guess that I will need a tree data structure like the oct-tree used for hexs. Do I even need this because, I can arbitrarily merge neighboring cells sharing a face as long as the resulting cell remains convex? What I mean is if a hex has been split into 8 subcells, I don't have to recover the original cell if I decide to do coarsening later on. I haven't consulted any literature, nor did I check thoroughly for existing libraries, which could save me a lot of time.