When advection, i.e. transport via fluid flow, is enabled within an AddiDict simulation setup, the governing flow field through the medium is calculated as the initial step.

For simulations involving slow, laminar flow the Stokes equation is the recommended option. Higher flow velocities require the application of the Navier-Stokes equation. When your structure includes porous material , i.e. regions not fully resolved within the geometry, the Brinkman term is appended to the flow equations to accurately represent flow behavior within these porous domains. The Brinkman term requires prior specification of the permeability of the porous media. Note that the inclusion of a porous material is a prerequisite for performing Adsorption simulations within AddiDict.

For further documentation regarding the available flow solvers and the underlying partial differential equations, refer to the FlowDict user guide.