AddiDict simulates how particles or chemical species move and interact within a fluid. Each AddiDict simulation follows these steps:

1. If advection, i.e. transport by moving fluid, is selected as transport mechanism the underlying flow through the medium is computed first. If the flow is laminar, Stokes or Stokes-Brinkman equations can be applied. For higher flow velocities the Navier-Stokes or Navier-Stokes-Brinkman equations should be used.
2. The movement of particles/molecules or a concentration field due to diffusion and/or advection is tracked.
   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. Adsorption and first order chemical reactions can be computed using either the tracked particles or the concentration field as a basis.