Including AD (Automatic Differentiation) to the Curl and Coupled Curl Operators

[csdechant]

Motivation

As the development and implementation of the electromagnetic module increases, there is a need to include the option to defined the curl and coupled curl operators as AD functions. This would avoid errors involving more complex formulations that include the curl of variables in lieu of using hand-coded Jacobians.

Design

A function, such as adCurlSln(), that calculates the curl of a variable as an AD variable should be included in the MooseVariableData file. Then the adCurlSln() function should be properly inherited by the additional MooseVariable files. To ensure that the AD curl operators are working as as intended, tests using type = 'PetscJacobianTester' should be added.

Impact

The inclusion of a AD versions of the curl and coupled curl operator will allow for faster development of additional physics into the MOOSE framework that utilizes the curl of variables.