Dynamics response to changes in operating conditions as a function of time can be modeled using the PEM Fuel Cell module. Examples include modeling a change in the cell voltage or current density, or inlet mass flow rates at the anode and/or the cathode. The procedure for setting up and solving transient PEM Fuel Cell problems is the same as that used for a normal Ansys Fluent transient problem as discussed in the Ansys Fluent User's Guide.

Assuming that the time scales associated with the electric fields are much smaller than those associated with the flow and thermal fields, the steady-state equations are retained for the two electric potentials (Equation 20–3 and Equation 20–4). Transient terms in all other equations such as momentum transport, energy transport, species transport, dissolved water transport (Equation 20–25), liquid water transport (the capillary pressure Equation 20–33), and the liquid saturation in gas channels (Equation 20–39), are activated.