Structurted mesh and unstructured mesh
 

Dear all,

I don't understand the exact definition of structured mesh and unstructured mesh. When do you call it structured mesh and when you don't? Could anyone help explain this to me?

Re: Structurted mesh and unstructured mesh
 

Structured: cells are can be accessed by index i, j, k cells have regular structured topography Unstrucured: cells located anywhere in mesh without any particular numbering sequence. cell topology is arbitrary

Re: Structurted mesh and unstructured mesh
 

Dear Wiroon,

A structured mesh is one in which the connectivity is implicit, its is possible to ascretian the neighbours of a cell i without any additional information. ( There is a definite ordering).

An unstrucured mesh is one in which connectivity is not implicit and must be provided explicitly, it is not possible to loacte the neighbours of a cell i if explicit connectivity is not given ( Arbitrary ordering)

Regards,

Ganesh

Re: Structurted mesh and unstructured mesh
 

All this is true, but notice: The definition belongs ONLY to the addressing of a cell, and not to the form (tet, hex, trimmed/cutted hex,poly, body fitted, ...).

E.g. ProStar of StarCD makes hex-meshes, wich can be carthesian, means 90° to each edge of the hex cell, but the internal access of Star to this cells is by a arbitrary ID-number.So this meshes are unstructured (!!!).

Sometimes people talk about structured meshes when the cells are hexaeder and in carthesian shape. That's not really the definition of "structured".

And Sometimes people talk about unstructred meshed and mean tet meshes. Tet cells are always unstructured, but again this is not really the definition.

Re: Structurted mesh and unstructured mesh
 

And what about the KIVA mesh? It is said that Kiva accepts only structured mesh. But in the latest versions the I-J-K notation is valid only in the fase of mesh creation with k3prep. The output of the k3prep preprocessor, i.e. the input mesh file for kiva3, itape17, does not know anithing about i-j-k. In fact, it contains node coordinates and the connectivity arrays (and boundary conditions..). It is not totally clear to me too.