| Matrix or Vector | Geometry | Shape Functions | Integration Points |
|---|---|---|---|
| Diffusivity Matrix and Diffusing Substance Generation Load Vector | Quad | Equation 11–140 | 3 x 3 |
| Triangle | Equation 11–119 | 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 | |
Diffusion in the Mechanical APDL 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.