OOF: Finite Element Analysis of Microstructures
| Submenus | Functions | Variables |
|---|---|---|
| select | new | transfer_method=election |
| add | transfer | transfer_time=automatic |
| subtract | transfer_replace=true | |
| delete | ||
| info | ||
| election_rules |
The /adaptive_mesh/groups submenu serves two purposes. It controls they way in which the groups assigned to pixels are transferred to (or inherited by) the mesh elements, and it allows you to explicitly create and manage element groups.
In the normal mode of operation (the mode in which you never look at this menu), pixels are assigned to pixelgroups, and the mesh automatically creates an elementgroup corresponding to each pixel group. Elements inherit their group properties from their pixels. The actual mechanism by which the inheritance takes place and when it happens are controlled by this menu.
In the default scheme, groups are transferred to the mesh automatically, on an as-needed basis. In effect, this means that the transfer takes place immediately--as soon as a group is defined, a pixel is assigned to a group, or a mesh is created or modified. This behavior can be changed with the /adaptive_mesh/groups/transfer_time variable, and the command /adaptive_mesh/groups/transfer can be used to force an immediate transfer.
The default method for deciding to which groups an element belongs is for the element to hold an election. The pixels in the image are divided into antagonistic political parties. All of the pixels in each party belong to the same set of pixelgroups and have the same material properties, including color. Each pixel votes for a representative pixel from its own party, and the element takes its groups from the winning candidate. (When a pixel lies on an element boundary, its vote is prorated by the fraction of the pixel that lies within the element.) The rules for conducting the election determine exactly how the pixels divide themselves into parties, and can be changed in the /adaptive_mesh/groups/election_rules menu.
The elements do not have to hold elections to choose their groups. The /adaptive_mesh/groups/transfer_method variable allows you to choose other simpler techniques, and groups can be assigned by hand to selected elements with /adaptive_mesh/groups/add and removed with /adaptive_mesh/groups/subtract.
