Objects and Methods

Pipe Junction

This object models a Pipe Junction. It simulates the split or junction of pressurized flow.

General Slots

Flow 1

Type: SeriesSlot

Units: Flow

Description: Flow into or out of the object

I/O: Input, Output, or set through a link

Links: Usually linked

Flow 2

Type: SeriesSlot

Units: Flow

Description: Flow into or out of object

I/O: Input, Output, or set through a link

Links: Usually linked

Flow 3

Type: SeriesSlot

Units: Flow

Description: Flow into or out of the object

I/O: Input, Output, or set through a link

Links: Usually linked

The mass balance equation is as follows:

The Pipe Junction can be used to split flows similar to a bifurcation or bring flows together similar to a confluence. The linking necessary for these two setups is slightly different because of the signs of the flows. To join flows, the two incoming flows should be linked to Flow 1 and Flow 2, the outgoing flow should be linked to Flow 3. Optionally, select the Solve Flow 3 method to force the object to solve only in one direction, if necessary.

To model a splitting of flows, the incoming flow should be linked to Flow 3 and the two outgoing flows should be linked to Flow 1 and Flow 2. Optionally, select the Solve Flow 1 or Flow 2 Only, Solve Flow 1 Only, or Solve Flow 2 Only method to force the object to solve only in one direction, if necessary.

User Methods

Pipe Junction Solution Direction

The methods in this category are used to control the available dispatch methods and therefore which direction the pipe junction is solving. The none default methods may be selected in Rulebased Simulation when you need to control this direction.

Solve Flow 1, Flow 2, or Flow 3

This is the default method and should remain selected for basic simulation. There are no slots or calculations specifically associated with this method. It simply allows all dispatch methods to be active.

Solve Flow 1 or Flow 2 Only

This method may need to be selected in Rulebased Simulations if the Pipe Junction is solving in one direction only. When this method is selected, only the Solve Flow 1 or Solve Flow 2 dispatch methods are available.

Solve Flow 1 Only

This method may need to be selected in Rulebased Simulations if you want the Pipe Junction to solve in one direction only. When this method is selected, only the Solve Flow 1 dispatch method is available.

Solve Flow 2 Only

This method may need to be selected in Rulebased Simulations if you want the Pipe Junction to solve in one direction only. When this method is selected, only the Solve Flow 2 dispatch method is available.

Solve Flow 3 Only

This method may need to be selected in Rulebased Simulations if you want the Pipe Junction to solve in one direction only. When this method is selected, only the Solve Flow 3 dispatch method is available.

Pipe Junction Hydraulics

The user selectable methods for Pipe Junction Hydraulics include None and Propagate Head. None is the default method and performs no calculations. Propagate Head will use the input/linked value for the known head to calculate the unknown heads.

None

This is the default method and performs no calculations.

Propagate Head

This method will use the values for the known head to calculate the unknown heads.

Slots Specific to This Method

Flow 1 Head

Type: SeriesSlot

Units: Length

Description: Head at the Pipe Junction Flow 1.

I/O: Input or linked

Links: Usually linked to the head slot on another object

Flow 2 Head

Type: SeriesSlot

Units: Length

Description: Head at the Pipe Junction Flow 2.

I/O: Output

Links: Usually linked to the head slot on another object

Flow 3 Head

Type: SeriesSlot

Units: Length

Description: Head at the Pipe Junction Flow 3.

I/O: Output

Links: Usually linked to the head slot on another object

Convergence

Type: ScalarSlot

Units: No Units

Description: A value ranging from 0 to 1.0 used for convergence in all iterative calculations

Information: Input only, defaults to 0.001 if not input

I/O: Not linkable

The head must be specified for one of the known flow values. For example, if Flow 3 and Flow 2 are known, a value must be known (input, rules, or linked) for either flow 3 Head or Flow 2 Head. If both are specified, they must be within convergence of each other or an error message will be posted. If neither are known, the method will stop and wait for a value to be known. The known head slot will be used to solve for the other two unknown head slots. All three head slots will have the same head value.

Dispatch Methods

This object solves for Flow 1, Flow 2, or Flow 3 depending on the knowns and unknowns.

Solve Flow 1

Following are the required knowns and unknowns (at the current timestep).

Required Knowns

• Flow 2

• Flow 3

Required Unknowns

• Flow 1

If a Hydraulic Calculation method is selected, the dispatch method will execute the selected method and set the appropriate Head slots. Next, the flows are set according to the following equation:

Solve Flow 2

Following are the required knowns and unknowns (at the current timestep).

Required Knowns

• Flow 1

• Flow 3

Required Unknowns

• Flow 2

If a Hydraulic Calculation method is selected, the dispatch method will execute the selected method and set the appropriate Head slots. Next, the flows are set according to the following equation:

Solve Flow 3

Following are the required knowns and unknowns (at the current timestep).

Required Knowns

• Flow 1

• Flow 2

Required Unknowns

• Flow 3

If a Hydraulic Calculation method is selected, the dispatch method will execute the selected method and set the appropriate Head slots. Next, the flows are set according to the following equation:

Revised: 06/03/2019