N O F L U X

Select Apply for all species to specify no flux for all species. Select Apply for to specify no flux for each species individually. To use another boundary condition for a specific species, click to clear the check box for that species.

Outflow

The Outflow feature is the preferred boundary condition at outlets where the species are to be transported out of the model domain. It is useful for example in mass transport models where it is assumed that convection is the dominating effect which causes the mass flow through the outflow boundary. The boundary condition is applied to all species and corresponds to the following equations depending on the selected diffusion model:

• For the Mixture-averaged diffusion model:

• For the Fick’s law diffusion model:

B O U N D A R Y S E L E C T I O N

From the Selection list, choose the boundaries to apply an outflow boundary condition.

P A I R S E L E C T I O N

If Outflow is selected from the Pairs menu, choose the pair to define. An identity pair has to be created first. Ctrl-click to deselect.

Flux Discontinuity

The Flux Discontinuity node represents a discontinuity in the mass flux across an interior boundary:

where the value of N0 (SI unit: kg/(m2·s)) specifies the size of the flux jump evaluated from the down to the up side of the boundary. This boundary condition is only available on interior boundaries.

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