Pseudo Time Stepping for Mass Transport

In order to improve the solution robustness, pseudo time stepping can be used for the Transport of Concentrated Species interface when solving a stationary model. Using pseudo time stepping, a fictitious time derivative term:

is added to the left-hand side of the mass fraction equations. Here ρ is the fluid mixture density, ωi is the mass fraction (dimensionless) of species i, and

is the pseudo time step. Since ωi−nojac(ωi) is always zero, this term does not affect the final solution. It does, however, affect the discrete equation system and effectively transforms a nonlinear iteration into a time step of size


	For a description of the pseudo time step term for the Navier-Stokes equations and the pseudo time step see and Pseudo Time Stepping in the COMSOL Multiphysics Reference Manual.