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The BOUNDARIES section is used to describe the problem domain over which the specified equation system is to be solved, and to specify boundary conditions along the outer surfaces of this domain.

Because of the history of FlexPDE, the discussion of boundaries has a strong two-dimensional orientation.  Three-dimensional figures are made up by extruding a two-dimensional domain into the third dimension.  One-dimensional domains are constructed by specializations of 2D techniques.

 

Every problem descriptor must have a BOUNDARIES section.

Problem BOUNDARIES are made up by walking the periphery of each material region on boundary paths through a 2D Cartesian space.

In this way, the physical domain is broken down into REGION, FEATURE and EXCLUDE subsections.  

Every problem descriptor must have at least one REGION subsection.   FEATURE and EXLUDE subsections are optional.

 

For concrete examples of the constructs described here, refer to the sample problems distributed with the FlexPDE software.