Boundary

Boundaries in FlowDesigner are starting and end points in the hydraulic model. These can be represented through any of the nodes below:

• Assigned Flow

• Assigned Pressure

• Reservoir

• Open Pipe End

• Sprinkler

Knowing the techniques on representing boundaries is an important skill when building hydraulic models. Several considerations in mind are the following:

1. Boundaries that represent a start of model or inlet boundaries serve as fluid and temperature data for the hydraulic model. Hence, the boundaries to be used should have a fluid and temperature field at its input panel and thus, only the following boundaries can be used:

• Assigned Flow

• Assigned Pressure

• Reservoir

1. The solver decides which among the boundaries acts as the inlet based on it configuration to drive flow from the node such as:

• Relative elevation with the other boundaries

• Relative pressure with the other boundaries

• Relative elevation and pressure with other boundaries

• Flow direction set for Assigned flow nodes

• Relative location of boundary towards a booster or flow control valve inlet

1. Any of the available boundary nodes can be used as outlet. However, note that when an assigned pressure or reservoir node is used, the fluid and temperature definition for the node is not utilized by the solver.

2. Boundaries can be directly represented as flow or pressure but not both at the same time. However, both ends of a model can be configured in a way that it could meet pressure and flow definitions. This serves the same purpose as if both flow and pressure are defined at one point in the model. For example:

• When using an assigned flow node as a boundary, applying an assigned pressure node at the other end can be defined with a pressure setting that meets the requirement at the assigned flow node.

• When using an assigned pressure node as inlet boundary, the pressure and /or elevation setting of an assigned pressure boundary acting as outlet can be configured in such a way that the pressure gradient is enough to meet a required flow.

Required Input Data

Assigned Pressure

Variable	Description
Identification Tag	Descriptive label or equipment identification number of vessel or fixed pressure piping being modelled
Status	Operating condition of the vessel or fixed pressure piping whether its should be considered (Status On) or not (Status Off) in the calculation
Elevation	Vertical distance between the pressure point of measurement relative to a common baseline applied for all nodes in the hydraulic model
Pressure Model	Point of pressure measurement whether taken near pipe wall /vessel /reservoir (Static) or at pipe center (Stagnation).
Pressure	Numerical value of pressure to be defined to the corresponding unit of measure.
Temperature	Numerical value of temperature to be defined to the corresponding unit of measure. When the assigned pressure node acts as the inlet boundary, defined temperature data will be used in the calculation. If the node is used as outlet boundary, the input data is not applied in the calculation.
Fluid	Assigned fluid name from the database. When the assigned pressure node acts as the inlet boundary, fluid physical property information stored in the database will be used in the calculation. If the node is used as outlet boundary, the defined fluid and its data is not applied in the calculation.