GoldSim allows you to specify that suspended Solids are present in the Pipe. These Solids are assumed to be advected and dispersed along the Pipe, but are not subject to retardation processes or interactions with storage zones. Species which partition onto the suspended Solids are transported with them as they move through the Pipe.
Suspended solids are specified to be present in the Pipe via the Suspended Solids… button on the Pipe dialog. When you press this button, the following dialog is displayed:
A Pipe can have a single suspended Solid for which you must define the Solid Medium and the Concentration:
Solid Medium: This is the solid suspended in the Pipe. It must be a previously defined Solid medium.
Concentration: This is the concentration of the suspended solid in the Pipe fluid. It has dimensions of mass per volume.
Suspended solids in a Pipe can increase the "carrying capacity" of the water in the mobile zone, by allowing solute species to sorb onto and be transported by particulates. This has the effect of reducing retardation due to sorption onto infill material and coating, as well as the effects of any matrix diffusion or stagnant zones which have been defined. Mathematically, suspended solids in a Pipe can be thought of as increasing the effective concentration in the pathway fluid, thereby increasing the mass flux of species out of the Pipe. In particular, assuming no dispersion, the advective mass flux of species i leaving the Pipe, Fluxi, becomes:
Fluxi = Q cdi (1 + Ki Vsusp csusp)
where Q is the flow rate in the Pipe (volume/time), cdi is the dissolved concentration of species i (mass/volume), Ki is the partition coefficient for species i for the suspended solid medium (volume/mass), csusp is the suspended solid concentration (mass/volume), and Vsusp is the dimensionless Advective Velocity Multiplier for the suspended Solid (a property of the Solid).
Note: The suspended solid
concentration only impacts advective mass flux links leaving the Pipe and does
not have any impact on the diffusion of particulates into the Pipe. That is, if
a diffusive mass flux link is created between a Cell containing a
suspended solid and a Pipe containing the same suspended solid, for the purpose
of simulating the diffusive flux of particulates, the concentration of
particulates on the Pipe side of the link is assumed to be zero.
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