Adding Face and qp time derivative evaluation for Finite Volume Variables

[tanoret]

Reason

The time derivative of MooseVariableFV is currently only available via an ElemArg. This limits the usage of the MooseVariableFV in contexts in which the time derivative is required at the faces or at quadrature points for two-phase material evaluations.

Design

Two new functions need to be implemented in MooseVariableFV

  DotType evaluateDot(const FaceArg & face, const StateArg &) const override;
  DotType evaluateDot(const ElemQpArg & elem_qp, const StateArg &) const override;

Impact

Extending the time derivatives arguments for evaluation in MooseVariableFV will enable its usage for two-phase flow in which the times derivative are needed throughout the domain to compute the acceleration forces and Basset forces for face interaction.