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Bifurcation
Objects and Methods
Bifurcation
This object models a bifurcation (division into two or more branches) of water.
General Slots
Inflow
Type: Multislot
Units: Flow
Description: the general flows into the bifurcation object, which can be split
Information: This multislot is a general slot used by the user methods: Two Outflows and Fractionally Split Outflows.
I/O: Optional: can input, set by propagation across a link, set via rules, or calculated (only if the Two Outflows method is selected). Inflow must be input, set via link propagation, or by rules if the Fractionally Split Outflows method is selected.
User Methods
Bifurcation Outflow
This method category allows the user to specify the number of destinations to which outflow can be sent.
* Two Outflows
The Two Outflows method is the default method. The Outflow1 and Outflow2 slots are specific to the Two Outflows method. No calculations are actually performed by this user method. It dictates that the object can dispatch with the following methods only: solveInflow, solveOutflow1, or solveOutflow2.
Slots Specific to This Method
Outflow1
Type: AggSeriesSlot
Units: Flow
Description: outflow from one side of the bifurcation
Information:  
I/O: Optional: can be input, set via rules, set by propagation across a link, or calculated
Outflow2
Type: AggSeriesSlot
Units: Flow
Description: outflow from the other side of the bifurcation
Information:  
I/O: Optional: can be input, set via rules, set by propagation across a link, or calculated
* Fractionally Split Outflows
Fractionally Split Outflows splits the Outflow to two or more destinations. Two slots are specific to the Fractionally Split Outflows method: Outflow Fractions Table and Split Outflows. The Split Outflows slot is a noComputeMultislot allowing the user to split outflows to multiple destinations. Each of the multiple outflows is represented by a subslot in the Split Outflows multislot. A subslot is created automatically each time the Split Outflows slot is linked to a destination object. The Outflow Fractions Table contains one column per subslot on the Split Outflows multislot. Each column contains the fraction multiplier dictating what fraction of the total outflow goes to each destination.
The number of outflows solved for depends on the number of links the user has specified from the Split Outflows noComputeMultislot to destination objects.
The multiple outflows are calculated as follows.
where i is the column of the Outflow Fractions Table. The first column on the Split Outflows multislot is the multislot itself and is not one of the subslots. It is set as the sum of all the subslot values. Therefore it should be equal to the total outflow from the Bifurcation object. The following slots are instantiated when this method is selected.
Slots Specific to This Method
Outflow Fractions Table
Type: TableSlot
Units: Fraction
Description: a table giving the proportion of outflow going to each Split Outflows subslot.
Information: The values in this slot should add up to 1.0. For example, if there are two columns and the inflow is split evenly, 0.5 would go into one column and 0.5 would go into the second column. The table will have the same number of columns as the number of links to the Inflow multislot. The columns are automatically added and named whenever a link is added to the Split Outflows noComputeMultislot.
I/O: Required Input
Split Outflows
Type: NoComputeMultislot
Units: Flow
Description: the multiple (or split) outflows based on the Outflow Fractions Table.
Information: The subslots of this multislot contain the multiple outflows. A subslot is created when the user links this slot to a destination object.
I/O: Output only
Bifurcation Solution Direction
This method category is used to specify the direction in which the Bifurcation solves (downstream given inflow and one outflow or the outflow fractions; upstream given the outflows). For basic Simulation runs direction does not make a difference and the default method should remain selected. However, in Rulebased Simulation the user may need to limit the Bifurcation to a downstream direction only. If necessary, the Bifurcation can be forced to solve for only Outflow1 or Outflow2 using the appropriate method.
* Solve Upstream or Downstream
The Solve Upstream or Downstream method is the default user method. If this method is active, it allows all dispatch methods to be active. No slots or calculations are specifically associated with this method.
* Solve Downstream Only
This method allows the Bifurcation object to only solve in the downstream direction with the following dispatch methods: solveOutflow1, solveOutflow2, or solveSplitOutflows. No slots are specifically associated with this method.
* Solve Outflow1 Only
This method allows the Bifurcation object to only solve for Outflow1 using the solveOutflow1 dispatch method. No slots are specifically associated with this method.
* Solve Outflow2 Only
This method allows the Bifurcation object to only solve for Outflow2 using the solveOutflow2 dispatch method. No slots are specifically associated with this method.
Dispatch Methods
This object solves for inflow, outflow1, outflow2, or splitOutflows depending on the knowns and unknowns.
* solveInflow
Solves for Inflow. This dispatch method is available only if the Solve Upstream or Downstream and Two Outflows user methods are active.
Required Knowns
Required Unknowns
• Inflow
The equation for this dispatch method is as follows.
* solveOutflow1
Solves for Outflow1. This dispatch method is available only if the Two Outflows user method and one of the following is active: Solve Upstream or Downstream, Solve Downstream Only, or Solve Outflow1 Only.
Required Knowns
• Inflow
Required Unknowns
The equation for this dispatch method is as follows.
* solveOutflow2
Solves for Outflow2. This dispatch method is available only if the Two Outflows user method and one of the following is active: Solve Upstream or Downstream, Solve Downstream Only, or Solve Outflow2 Only.
Required Knowns
• Inflow
Required Unknowns
The equation for this dispatch method is as follows.
* solveSplitOutflows
Sets the Split Outflows calculated by the Fractionally Split Outflows method. This dispatch method is specifically associated with the Fractionally Split Outflows user method. It does not depend on the bifurcation solution direction.
Required Knowns
• Inflow
• Outflow Fractions Table
Required Unknowns
This dispatch method sets the multislot and subslots of the Split Outflows noComputeMultislot. Actual calculations are performed by the user method Fractionally Split Outflows.
Revised: 06/03/2019