Page 400 - ExtendSim User Guide

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Rates, Constraints, and Movement
Flow rules
Block Convey Flow
Diverge
Interchange Merge Sensor
Tank
Throw Flow Valve
Always defines a new rate section?
Yes Yes
Yes Yes No Yes No No
Comments
The outflow effective rate can be different than the out- flow effective rate because it is a residence block.
The effective rates can be different across all flow con- nectors – the input and all the outputs.
See Convey Flow comment
See Diverge comment
The inflow and outflow effective rates are the same. See Convey Flow comment
The inflow effective rate is the same as the throw rate. The inflow and outflow effective rates are the same.
rate sections, see the “Comprehensive example” on page 383.
For an example of
Rate precision
The mathematical precision for effective rates is limited to 12 digits. This can become an issue if you separate any two effective rates in an area by more than 12 digits of precision. For more information, see “Precision” on page 432.
LP area
While rate sections don’t change after the start of a run, the boundaries of the LP area change dynamically during the simulation. An LP area is composed of one or more rate sections linked together by the fact that their effective rates could change during the simulation run. When an event occurs that causes the effective rate for one rate section to be reevaluated, ExtendSim determines which other rate sections might be impacted. The affected rate sections constitute the LP area and become part of the LP calculation.
Since the LP area is computed internally, and because it is most important for the LP calcula- tion, it is discussed fully in “The LP area” on page 449.
Flow rules
Flow rules completely define how a block permits flow to move through during the simula- tion run. When calculating rates of flow, ExtendSim's discrete rate architecture tries to maxi- mize throughput throughout the system, subject to a set of constraints. In order to restrict flow, discrete rate blocks are required to define their own sets of flow rules. The aggregated set of these rules ultimately defines how fast flow is permitted to move over time throughout the model.
A block’s particular set of flow rules is derived from four factors:
• Theblock’sfundamentalbehavior.
• Howitsdialoghasbeenconfigured,suchassettingaTank’smaximuminputrateorentering a conversion factor in the Change Units dialog.
Discrete Rate
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