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FEATURE subsections are used to describe non-closed entities which do not enclose a subdomain with definable material parameters.

FEATURE subsections are formed in the same manner as REGION subsections and can use all the same LINE and ARC segments.  

FEATURE subsections do not end with the reserve word CLOSE.

A FEATURE will be explicitly represented by nodes and cell sides.

FEATURE subsections are used when a problem has internal line sources; when it is desirable to calculate integrals along an irregular path; or when explicit control of the grid is required.

In 3D problems, FEATURES should be used to delineate any sharp breaks in the slope of extrusion surfaces.  Unless mesh lines lie along the surface breaks, the surface modeling will be crude.

 

Example:

REGION 1        { an outer box }

START(0,0) LINE TO (10,0) TO (10,10) TO (0,10) TO CLOSE

 

FEATURE        { with a diagonal gridding line }

START(0,0) LINE TO (10,10)