CHBDYG

Geometric Surface Element Definition (Grid Form)

Description: Defines a boundary condition surface element for heat transfer analysis without reference to a property form.

Format:

Example:

Field	Definition	Type	Default
EID	Surface element identification number.	Integer > 0	Required
TYPE	Surface type, see Remark 2.	Character	Required
IVIEW	A VIEW identification number.	Integer > 0
RADMID	RADM identification number.	Integer > 0
Gi	Grid point identification numbers of grids bounding the surface.	Integer > 0	Required

Remarks:

1. Element identification numbers must be unique with respect to all other element identification numbers.
2. TYPE specifies the kind of element surface. Supported types are REV, AREA3, AREA4, AREA6, and AREA8.
   • TYPE = REV

     The REV type has two primary grid points that must lie in the x-z plane of the basic coordinate system. A midside grid point G3 is optional and supports convection or heat flux from the edge of the six-noded CTRIAX6 element. The defined area is a conical section with z as the axis of symmetry. A property entry is required for convection, radiation, or thermal vector flux (see Figure 1).

   • TYPE = AREA3, AREA4, AREA6, or AREA8

     These types have three and four primary grid points, respectively, that define a triangular or quadrilateral surface and must be ordered to go around the boundary. A property entry is required for convection, radiation, or thermal vector flux (see Figures 2 and 3).

3. These types have three and four primary grid points, respectively, which define a triangular or quadrilateral surface and must be ordered to go around the boundary.
4. For defining the front face, the right-hand rule is used on the sequence G1 to G2 to … Gn of the grid points.
5. All conduction elements to which any boundary condition is to be applied must be individually identified with one of the surface element entries: CHBDYG or CHBDYP.

Figure 1. Normal Vector for CHBDYG Element TYPE = REV

Figure 2. Surface TYPE Definition

Figure 3. Normal Vector for CHBDYG Element TYPE = AREAi

The unit normal is given by:

(G3 is used for triangles and G4 is used for quadrilaterals.)