You can define a coating medium for a Pipe which can act to retard transport through the pathway. This might be appropriate, for example, if you were simulating flow through a fracture which had a coating around the perimeter. The mobile fluid in the pore volume of the pathway, the immobile fluid within the coating material, the infill material and the coating material are all assumed to be at equilibrium at all times with respect to the partitioning of species.
You define a coating material via the Coating… button on the Pipe dialog. When you press this button, the following dialog is displayed:
The Coating Medium, if specified, must be an existing Solid medium in the model. If there is no coating medium in the pathway, you should leave this field blank (the default). The Coating Thickness specifies the thickness of the coating material along the perimeter, and has dimensions of a length.
The mass of Coating Medium per unit length of pathway (which impacts the degree to which the coating retards species) is simply the product of the Coating Thickness, the pathway Perimeter and the density of the Coating Medium.
Note: If the perimeter or the
coating thickness is specified as 0, the coating material will have no impact on
the behavior of the Pipe.