Direct transfer mass flux links are used to transport mass directly from one pathway to another via a mechanism that cannot be appropriately represented as either advection or diffusion. They are defined by specifying a fractional rate at which mass is being moved from one pathway to another. Hence, a direct transfer mass flux is computed as the mass of the species in the pathway multiplied by a fractional transfer rate:
Direct Transfer Mass Flux = Mass in Cell * Transfer Rate
The Transfer Rate has dimensions of inverse time. The Transfer Rate is specified as a vector by species. This allows the Transfer Rate to be species-specific.
Direct transfer mass flux links are uni-directional (mass can only be transported in one direction). That is, the Transfer Rate must be non-negative.
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