The Packed Bed includes two subnodes, Fluid and Pellets, which in turn are used to define the physical properties of the corresponding phase. The latter node is also used to define volumetric reactions, as well as heterogeneous reactions, occurring within the porous pellets.

The Packed Bed node requires a Porous Material (described in the COMSOL Multiphysics Reference Manual) on the domains occupied by the bed. Using the porous material it is possible to model a bed comprised of any number of pellet types by adding multiple pellet nodes.

For information on the equations solved in the pore space and inside the pellets see the section The Packed Bed Feature, in the Theory for the Transport of Diluted Species Interface chapter. When using the corresponding feature for concentrated mixtures, see The Packed Bed Feature in the Theory for the Transport of Concentrated Species Interface chapter.

From the Selection list, choose the domains with porous material. Note that all domains chosen needs to be occupied by a Porous Material.

Use the Porosity list to specify the bed porosity, that is the volume fraction not occupied by the pellets. Select From material to use the bed porosity defined by the Porous Material. Select User defined to enter a constant or an expression.