The entity definition elements set the initial points for the immersed boundaries and can override the default elastic properties of the immersed boundaries. Each statement has a required set of arguments and an optional list of modifiers. The required arguments place the entity in the physical domain, and the optional arguments change the elastic properties of that entity.
The entity definition elements of an IBIS program are:
The circle, ellipse, line and singlet statements establish either a circle of immersed boundary points, an ellipse of immersed boundary points, a line of immersed boundary points or a single immersed boundary point within the domain. The sine statement allows for the creation of sinusoidal patterns of immersed boundary points. The file and pfile statements allows for importing data into IBIS via a data file that is generated by some other means. The polygon statement allows for the construction of piecewise curves of immersed boundary points.
The polygon statement has its own set of subcommands that determine the curves of immersed boundary points. The polygon definition statements are:
Every entity can be made active by adding a -A name option in the entity definition statement. A complete description of the active elements are given in ACTIVE ENTITY DEFINITION section of this guide.