Page 138 - ExtendSim User Guide
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Adding complexity
Choose Select item animation from the popup menu Select Car from the animation object popup menu Click OK to close the dialog
Select the command Run > Show 2D Animation Run the simulation
Now cars are displayed as they flow through the model. With animation on, it is easy to see that cars are arriving faster than they can be washed.
Animation is very useful for debugging models or for making presentations, but it can consid- erably increase the time it takes a simulation to run. To turn animation off, unselect the com- mand Run > Show 2D Animation or unselect the Animation On/Off tool in the toolbar.
Adding complexity
Now that you understand how to build the basic model, you can add more details and features.
Creating a second wash bay
Since long lines deter customers, it would be better to keep the entry line short. There are two ways to model this:
• IncreasetheprocessingcapabilityoftheActivityblock
• Add a second wash line
Both of these are examples of parallel processing (described in more detail on page 180.)
To increase the number of cars that the wash bay can process at a time, you would simply change the capacity setting in the Activity’s dialog. For instance, allowing a maximum of 2 items in the Activity would simulate a wash bay that could wash two cars at a time.
Since the assumptions state that the final model has two bays, instead of increasing the Activ- ity’s capacity you will add a second bay:
Copy the Activity block in the Car Wash model and paste it below the original Activity block. Label the new block “Wash Bay 2”.
Connect the Queue’s item output to the item input on Wash Bay 2. This creates a parallel connection with the original wash bay.
Expand the Exit block’s variable input connector so that it reveals a second input.
Adding a second bay
Connect Wash Bay 2’s item output to the Exit block’s second item input. Save and run the simulation.
With the second wash bay, the entry line length stays near 0 most of the time, as shown in the plotter and the Queue block’s Results tab.
Discrete Event

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