The Species Tab in Multi-Species Model dialog box is used to define each of the chemical/biological species being simulated.
| Field | Description |
|---|---|
| Name | Species name. |
| Description | Description of Species. |
| Unit | Species mass units. Bulk species are measured in concentration units of mass units per liter while wall species are measured in mass units per unit area which is defined in General Tab. |
| Abs. Tol. | The optional absolute tolerance that overrides the global value set in the General section. |
| Rel. Tol. | The optional relative tolerance that overrides the global value set in the General section. |
| Global Init. | The global initial water quality value for the species. |
| Type | Species type which is Bulk or Wall. |
| P Type | Expression format to define the reaction dynamics of the species in pipes. The selections are: No Expression, Rate, Formula and Equilibrium. |
| T Type | Expression format to define the reaction dynamics of the species in tanks. The selections are: No Expression, Rate, Formula and Equilibrium. |
| P Term | Term ID for the mathematical expression to define the reaction dynamics of the species in pipes. |
| T Term | Term ID for the mathematical expression to define the reaction dynamics of the species in tanks. |
| Diffusivity | Defines the relative diffusivity of the species to be included when modeling longitudinal dispersion. A value of 1 corresponds with the diffusivity of chlorine in water at 20 deg C (0.00112 ft2/day).
Note: Dispersion can be neglected by setting diffusivity to zero. This can improve overall run performance.
|
Remarks:
- There should be one expression supplied for each species defined in the model.
- The EQUIL expression format is used for equilibrium expressions where it is assumed that the expression supplied is being equated to zero. Thus formally there is no need to supply the name of a species, but requiring one encourages you to make sure that all species are accounted for.
- The RATE expression format is used to supply the equation that expresses the rate of change of the given species with respect to time as a function of the other species in the model.
- The FORMULA format is used when the concentration of the named species is a simple function of the remaining species.