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Pipeline
Objects and Methods
Pipeline
This object models fully-pressurized flow through a pipeline.
General Slots
Inflow
Type: SeriesSlot
Units: FLOW
Description: Flow rate at the entrance of the object.
I/O: Can be input, output, or set by propagation across a link
Outflow
Type: Series Slot
Units: FLOW
Description: Flow rate at the exit of the object.
I/O: Can be input, output, or set by propagation across a link
User Methods
Pipeline Solution Direction
This method category is used to specify the direction the Pipeline solves (downstream given inflow or upstream given outflow). For basic Simulation runs this does not make a difference and the default method should remain selected. However, in Rulebased Simulation the user may need to limit the Pipeline to downstream solution only.
* Solve Upstream or Downstream
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 Downstream Only
This method may need to be selected in Rulebased Simulations where the Pipeline can solve in the downstream direction only. When this method is selected, only the solveOutflowGivenInflow dispatch method is active.
Head Loss
The user selectable methods for Head Loss include None and Hazen-Williams Equation. None is the default method and makes no other calculations. Hazen-Williams Equation will calculate Inflow Head given Outflow Head or Outflow Head given Inflow Head. The selected method executes from the dispatch method.
* None
This is the default method and makes no calculations.
* Hazen-Williams Equation
This method calculates Inflow Head given Outflow Head (and other inputs) or Outflow Head given Inflow Head (and other inputs). These inputs include pipe diameter, pipe length, the C Value of the Pipeline, and minor losses within the Pipeline.
In this method, either Inflow Head or Outflow Head must be given (either set as an input, by rules, or set through a link) in order to calculate the other. If Inflow Head is input or set through a link, Outflow Head is calculated. If Outflow Head is input or set through a link, Inflow Head is calculated.
The following slots will be instantiated when using the Hazen-Williams Equation method.
Slots Specific to This Method
Inflow Head
Type: SeriesSlot
Units: Length
Description: Inflow Head of the Pipeline object. This is equal to the total head, which includes pressure, elevation, and velocity components. This value likely comes from a link or is calculated.
I/O: Input or Output
Outflow Head
Type: SeriesSlot
Units: Length
Description: Outflow Head of the Pipeline object. This is equal to the total head, which includes pressure, elevation, and velocity components. This value likely comes from a link or is calculated.
I/O: Input or Output
Type: Usually linked to the head slot on another object
Diameter
Type: ScalarSlot
Units: Length
Description: Diameter of the Pipeline. It is assumed constant over its length. It must be greater than zero.
I/O: Input only
Velocity
Type: SeriesSlot
Units: Velocity
Description: Velocity of the water within the Pipeline.
I/O: Output only
Length
Type: ScalarSlot
Units: Length
Description: Length of the Pipeline. The length must be greater than or equal to zero.
I/O: Input only
C Value
Type: ScalarSlot
Units: NoUnits
Description: Hazen-Williams C Value of the Pipeline. The C Value depends on the pipe material, pipe age, tuberculation, lining, etc.... Values can be found in a hydraulics text and vary between 80-150.
I/O: Input only
Minor Losses
Type: ScalarSlot
Units: Length
Description: Minor Losses at the Pipeline. The value defaults to zero if less than zero or not input.
I/O: Input only
The head loss will be calculated using the Hazen-Williams formula, as follows:
Rh is the hydraulic radius. For a circular pipe:
V is the velocity of the water within the pipeline, as follows:
C is the user input Hazen-Williams C Value of the pipe, as follows:
S is the slope of the energy grade line, as follows:
Note:  The empirically-derived Hazen-Williams formula is unit-specific. Published in literature, k for British units is 1.318 and 0.85 for SI units. In RiverWare, the formula uses S.I. units, in which head loss has units of meters, Length has units of meters, Velocity has units of meters/second, the C Value has no units, and Diameter has units of meters. Unfortunately, k =1.318 for British and k = 0.85 for SI are not equivalent when converted. As a result, RiverWare will use the more common and more significant value of k = 1.318. In SI units, this is equivalent to 0.8492.
Rearranging the Hazen-Williams formula, head loss can be solved as follows:
Depending on inputs, Outflow Head or Inflow Head is set to one of the following:
• 
• 
Dispatch Methods
This object solves for inflow or outflow, whenever the other is known. If the Solve Upstream or Downstream method is selected, then all dispatch methods are active. However, if Solve Downstream Only is selected, then only the solveOutflowGivenInflow method is active.
* solveOutflowGivenInflow
Solves for outflow.
Required Knowns
• Inflow
Required Unknowns
• Outflow
If an inflow head is linked, the dispatch method will wait for a value in this slot before solving. The equation for this dispatch method is as follows:
* solveInflowGivenOutflow
Solves for Inflow.
Required Knowns
• Outflow
Required Unknowns
• Inflow
If an outflow head is linked, the dispatch method will wait for a value in this slot before solving. The equation for this dispatch method is as follows:
 
Revised: 06/03/2019