Page 376 - ExtendSim User Guide
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Creating Flow
Creating flow
Fruit Supply had infinite initial contents, while the Tank that stored the Yogurt product had no initial contents.
If the option for Finite initial contents with flow attribute values is selected, a check box causes the initialization to be repeated whenever the Tank becomes empty.
☞ If a Tank has no inflow connections, by definition it is being used as a source. If at some point the source reaches the empty state, the effective outflow rate will remain at zero for the remainder of the simulation run.
Interchange block modes
The Interchange block represents a tank, or holding area, where flow can interact with items generated by discrete event blocks. Flow can enter the Interchange block not only through its inflow connector but also through the arrival of an item. Conversely, flow can exit the block through its outflow connector or through the exiting of an item.
The Interchange block has two options that affect how the block’s initial contents and maxi- mum capacity are set:
• Tankonlyexistswhileitemisinit.Thisbehaviorisanalogoustoatruck(anitem)that arrives at a loading dock (a tank) where the loading or unloading of product can take place at a certain rate. The truck arrives with a capacity and perhaps some quantity of product already in it. As long as the truck is in the dock, loading or unloading is possible and occurs at the specified rate. When the truck leaves, the dock’s ability to load and unload product disappears (the inflow and outflow effective rates are set to zero).
• Tankisseparatefromitem.Thisbehaviorissimilartoatruck(anitem)thatbringsproductto a holding area (a tank) that may nor may not contain product. The truck empties its load and perhaps takes some of the holding area’s product with it when it leaves. This process occurs instantaneously. Whether the truck is at the holding area or not, both the truck and the hold- ing area can have product. The holding area can receive or deliver flow to the system even if there is no truck (the inflow and outflow effective rates can be greater than zero).
☞ For more details about these two modes, see “Interchange modes” on page 426.
Depending on the option selected, the Interchange has different choices for setting an initial
Initialization of contents when “Tank only exists while item is in it”
This choice allows the block to have an initial contents only when an item arrives. To set an initial contents for this block, choose one of the options from the dialog’s popup menu, shown here:
Interchange initial contents, default behavior
• Aconstant.Enteranumberinthefield;thedefaultis0.Tocausetheinitialcontentstobe infinite, check the field’s (infinite) check box or set the field to blank.
• ValueatICO.Thevalueatthisconnectorwillcontroltheinitialcontents.
• Valueofitemattribute.Selectanitem’sattributeinthedialog.Whenanitemarrives,theini- tial contents will equal that attribute’s value.
Discrete Rate

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