13.238. PLANE238 - 2D 8-Node Diffusion Solid

Matrix or Vector	Geometry	Shape Functions	Integration Points
Diffusivity Matrix and Diffusing Substance Generation Load Vector	Quad	Equation 11–143	3 x 3
	Triangle	Equation 11–121	6
Damping Matrix	Same as diffusivity matrix. If KEYOPT(1) = 1, matrix is diagonalized as described in Lumped Matrices
Diffusion Flux Load Vector	Same as coefficient matrix, specialized to the face		2

13.238.1. Other Applicable Sections

Diffusion in the Theory Reference describes the derivation of the diffusion element matrices and load vectors as well as diffusion flux evaluation. If KEYOPT(1) = 1, the damping matrix is diagonalized as described in Lumped Matrices.

13.238.2. Assumptions and Restrictions

A dropped midside node implies that the edge is straight and that the concentration varies linearly along that edge.