The simulation of mass transport by AddiDict is done in three main steps:

1. The underlying flow through the medium is computed using an appropriate flow solver (Explicit Jump (EJ), Simple Fast Fourier Transform (SimpleFFT) or LIR solver). If the flow is laminar, Stokes or Stokes-Brinkman equations for slow fluid flow can be applied.
   It is also possible to solve Navier-Stokes equations or Navier-Stokes-Brinkman equations to simulate non-laminar flow.
2. Either a predefined number of particles or molecules or a concentration field is tracked in the calculated flow field.
   Tracking of particles is based on solving an ordinary differential equation and includes electrostatic effects and diffusion. The latter becomes more and more relevant with smaller particle size. Particles are treated as objects moving independently from each other and using a distribution for the particle sizes is possible.
   Tracking of a concentration field utilizes a continuum-mechanical approach to model the transport phenomena, focusing on a concentration field as the primary variable. The concentration field represents the molar concentration of a solute, which is a dissolved substance within a solvent (the carrying fluid).
3. The particles or concentration field have to be inserted into the space enabling fluid flow. Both can start in pores and in porous material of the structure.
   The manner of particle injection is crucial for the resulting transport simulation and so a variety of options are implemented. These include different 2D and 3D geometries for particle starting positions, definition of initial particle velocity and injection can also follow a temporal distribution function (Uniform, Gaussian or stepwise defined probability distribution).
   For the concentration field an inflow concentration is defined that enters the structure either with the flow or by diffusion only depending on the defined transport mechanisms. It is also possible to start from an initial distribution defined by a volume field.