PDE Interface Variables
The following list shows symbolic expressions for quantities appearing in the definition of PDEs and the corresponding variable names, which can be used in PDE coefficients and are available for results evaluation and visualization
Expression
Name
Description
 ui
ui
The solution variable (dependent variable)
uixj
The derivative of the solution variable ui with respect to the spatial coordinate xj, for example, uy
uiTxj
The xj component of the gradient of ui projected onto a boundary or edge, for example, uTy
uixjxk
The second derivative of the solution variable ui with respect to the spatial coordinates xj and xk, for example, uxx, uxy
uit
The derivative of the solution variable ui with respect to time
uitt
The second derivative of the solution variable ui with respect to time
uixjt
The mixed derivative of the solution variable ui with respect to time and the spatial coordinate xj