Convective Term Formulation
When modeling mass transport in the Nernst-Planck Equations interface, two formulations are available for the convective term: a conservative and a nonconservative formulation. Equation 3-88 shows the conservative formulation.
In the nonconservative formulation the velocity is moved out of the divergence operator, which improves the stability of systems coupled to a momentum balance (fluid-flow equation). This is only applicable to systems that contain incompressible fluids. In these fluids, the following continuity equation is satisfied:
(3-93)
and Equation 3-88 can be rewritten as:
(3-94)
which can be called the nonconservative formulation and is the default formulation in the Nernst-Planck Equations interface.
Specify the equation formulation in the Advanced Settings section of the Nernst-Planck Equations interface.