Page 51 - ExtendSim User Guide
P. 51

Opening a new model worksheet
To start a new model: Choose File > New Model.
ExtendSim opens a blank model worksheet titled Model-x.
Setting the simulation parameters
You enter simulation parameters, such as the model’s time units and duration, in the Simulation Setup com- mand.
Choose the menu command Run > Simulation Setup
Building a Model 25
Opening a new model worksheet
New model worksheet (Windows)
The Simulation Setup command opens a dialog for setting a variety of simulation and 3D ani- mation parameters, such as how long and how many times the simulation will run, when the random number seed gets reset, the mode of interaction between the simulation and the 3D window, and so forth. The dialog has tabs for Setup, Continuous, Random Numbers, 3D Ani- mation, and Comments.
The most common simulation settings you will need to enter in the Simulation Setup window (and often the only ones) are the End time and Global time units parameters located on the Setup tab. For most purposes, you want the simulation to start at the beginning, so you would use the default start time of 0.
Customize the Setup tab by entering the follow- ing parameters:
End time: 36
Start time: 0 (Default) Runs: 1 (Default) Global time units: Months Click OK
When it runs, the model will simulate 36 months of time, performing calculations once each month.
Each time you run a simulation, ExtendSim
uses the same values entered in the Simulation
Setup window. Thus, you will usually only configure the settings once per model. The Simula- tion Setup command is discussed fully in “Simulation setup” on page 594.
Building the model
The Reservoir model requires five blocks. There are two sources of water: rainfall and a stream; the data for rainfall comes from a table while the stream contributes a random amount. You need a block to add the two water sources, another block that can hold values (represent- ing the reservoir), and a plotter to display the results of the simulation.
Basic steps
The basic steps for building a model are:
Setup tab of Simulation Setup window

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