The EXTRUSION Section

 Top  Previous  Next

The layer structure of a three-dimensional problem is specified bottom-up to FlexPDE in the EXTRUSION Section:

 

EXTRUSION

SURFACE        "<Surface_name_1>"        Z = expression_1

LAYER        "<Layer_name_1>"

SURFACE        "<Surface_name_2>"        Z = expression_2

LAYER        "<Layer_name_2>"

. . .

SURFACE        "<Surface_name_n>"        Z = expression_n

 

The specification must start with a SURFACE and end with a SURFACE. 

LAYERS correspond to the space between the surfaces.  The LAYER specifications may be omitted if a name is not needed to refer to them.

 

•Surfaces need not be planar, and they may merge, but they must not cross.  expression_1 is assumed to be everywhere less than or equal to expression_2, and so on.  Use a MIN or MAX function when there is a possibility of crossover.
•Surface expressions can refer to regionally defined parameters, so that the surface takes on different definitions in different regions.  The disjoint expressions must, however, be continuous across region interfaces. (see example "Samples | Misc | 3d_Domains | Regional_surfaces.pde")
•If surface expressions contain conditional values (IF...THEN or MIN, MAX, etc), then the base plane domain should include FEATURES to delineate the breaks, so they can be resolved by the gridder. 
•Surfaces must be everywhere continuous, including across material interfaces.  Use of conditionals or regional definitions must guarantee surface continuity. 
•Surface expressions can refer to tabular input data (see example "Samples | Misc | 3D_Domains | Tabular_surfaces.pde").

 

The layer and surface names in these specifications are optional, and if layers have no names, the LAYER statements may be omitted.

 

Shorthand form

Stripped of labels, the EXTRUSION specification may be written:

 

EXTRUSION Z = expression_1, expression_2 [, ...]

 

In this form layers and surfaces must subsequently be referred to by numbers, with surface numbers running from 1 to n and layer numbers from 1 to (n-1).  SURFACE #1 is Z=expression_1, and LAYER #1 is between SURFACE #1 and SURFACE #2.

 

See the User Guide chapter Using FlexPDE in Three-Dimensional Problems for more information