Defines various simulation options.
HYDRAULICS USE/SAVE filename
QUALITY NONE/CHEMICAL/AGE/TRACE id
SPECIFIC GRAVITY value
UNBALANCED STOP/CONTINUE/CONTINUE n
DEMAND MULTIPLIER value
EMITTER EXPONENT value
UNITS sets the units in which flow rates are expressed where:
CFS = cubic feet per second
GPM = gallons per minute
MGD = million gallons per day
IMGD = Imperial MGD
AFD = acre-feet per day
LPS = liters per second
LPM = liters per minute
MLD = million liters per day
CMH = cubic meters per hour
CMD = cubic meters per day
AFD other input quantities are expressed in US Customary Units. If flow units are in liters or cubic meters then Metric Units must be used for all other input quantities as well. (See Units of Measurement). The default flow units are GPM.
HEADLOSS selects a formula to use for computing head loss for flow through a pipe. The choices are the Hazen-Williams (
H-W), Darcy-Weisbach (
D-W), or Chezy-Manning (
C-M) formulas. The default is
HYDRAULICS option allows you to either
SAVE the current hydraulics solution to a file or
USE a previously saved hydraulics solution. This is useful when studying factors that only affect water quality behavior.
QUALITY selects the type of water quality analysis to perform. The choices are
TRACE. In place of
CHEMICAL the actual name of the chemical can be used followed by its concentration units (e.g., CHLORINE mg/L). If
TRACE is selected it must be followed by the ID label of the node being traced. The default selection is NONE (no water quality analysis).
VISCOSITY is the kinematic viscosity of the fluid being modeled relative to that of water at 20 deg. C (1.0 centistoke). The default value is 1.0.
DIFFUSIVITY is the molecular diffusivity of the chemical being analyzed relative to that of chlorine in water. The default value is 1.0. Diffusivity is only used when mass transfer limitations are considered in pipe wall reactions. A value of 0 will cause EPANET to ignore mass transfer limitations.
SPECIFIC GRAVITY is the ratio of the density of the fluid being modeled to that of water at 4 deg. C (unitless).
TRIALS are the maximum number of trials used to solve network hydraulics at each hydraulic time step of a simulation. The default is 40.
ACCURACY prescribes the convergence criterion that determines when a hydraulic solution has been reached. The trials end when the sum of all flow changes from the previous solution divided by the total flow in all links is less than this number. The default is 0.001.
UNBALANCED determines what happens if a hydraulic solution cannot be reached within the prescribed number of
TRIALS at some hydraulic time step into the simulation.
STOP will halt the entire analysis at that point.
CONTINUE will continue the analysis with a warning message issued.
CONTINUE n will continue the search for a solution for another
n trials with the status of all links held fixed at their current settings. The simulation will be continued at this point with a message issued about whether convergence was achieved or not. The default choice is
PATTERN provides the ID label of a default demand pattern to be applied to all junctions where no demand pattern was specified. If no such pattern exists in the [PATTERNS] section then by default the pattern consists of a single multiplier equal to 1.0. If this option is not used, then the global default demand pattern has a label of "1".
DEMAND MULTIPLIER is used to adjust the values of baseline demands for all junctions and all demand categories. For example, a value of 2 doubles all baseline demands, while a value of 0.5 would halve them. The default value is 1.0.
EMITTER EXPONENT specifies the power to which the pressure at a junction is raised when computing the flow issuing from an emitter. The default is 0.5.
MAP is used to supply the name of a file containing coordinates of the network's nodes so that a map of the network can be drawn. It is not used for any hydraulic or water quality computations.
TOLERANCE is the difference in water quality level below which one can say that one parcel of water is essentially the same as another. The default is 0.01 for all types of quality analyses (chemical, age (measured in hours), or source tracing (measured in percent)).
- All options assume their default values if not explicitly specified in this section.
- Items offset by slashes (/) indicate allowable choices.
[OPTIONS] UNITS CFS HEADLOSS D-W QUALITY TRACE Tank23 UNBALANCED CONTINUE 10