Finite and Infinite Voids
For modeling with BEM, a geometry model can have multiple domains and multiple finite voids. However, there can be only one infinite void. These voids are only available for the PDE, Boundary Element interfaces and other interfaces that use BEM.
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A domain corresponds to a finite region where the geometry model is of the type solid. The geometry in most models based on FEM consists of domains only.
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Any other finite region is a finite void. A finite void is a closed empty region, and it can be created as a geometric primitive of type curve (in 2D) or surface (in 3D), for example. You can also create it using a Boolean difference operation that subtracts a closed domain from the rest of the geometry.
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The infinite void is the single unbounded region surrounding the geometry model. The infinite void is always domain number 0. An error message, for example, that refers to Domain 0 is then pointing to a possible problem in the infinite void.
If the model contains finite voids and an infinite void, those volumetric regions appear in the domain selection lists for BEM interfaces and in the Selection List window as Finite void 1, and so on, and as Infinite void. Finite voids have domain numbers −1, −2, and so on, corresponding to Finite void 1, Finite void 2, and so on. An error message, for example, that refers to Domain -2 is then pointing to a possible problem in Finite void 2. The infinite void is always domain number 0. An error message, for example, that refers to Domain 0 is then pointing to a possible problem in the Infinite void.