13.240. SOLID240 - 3-D 10-Node Tetrahedral Diffusion Solid

Matrix or Vector	Shape Functions	Integration Points
Diffusivity Matrix and Diffusing Substance Generation Load Vector	Equation 11–190	4
Damping Matrix	Same as diffusivity matrix. If KEYOPT(1) = 1, the matrix is diagonalized as described in Lumped Matrices	11
Diffusion Flux Load Vector	Equation 11–190 specialized to the face	6

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