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Tutorial for Discrete Rate Systems 337
A basic discrete rate model
☞ The Lookup Table block will actively output values at each specified time, based on entries in the table in its dialog, and does not need to be prompted for output. This is discussed in “Poll- ing constraints” on page 378.
Add a fruit processing line
So far you have created a yogurt processing line. The specification for the final model indi- cates that fruit is mixed with the yogurt, requiring a second processing line:
Delete the connection from the Valve to the Yogurt tank and move the tank to the right. Below the Lookup Table block of the yogurt processing line, add another Tank block to the
In the block’s Tank tab, check the checkbox in the field labeled Initial contents, causing the initial contents to be infinite.
In the block’s Options tab, select Flow group unit: gallons.
Label the block Fruit Supply.
Add a Valve to the right of the Fruit Supply tank.
Connect from the Fruit Supply tank’s outflow connector to the Valve’s inflow connec- tor.
In the Valve tab, enter Maximum rate: 8 gallons/minute.
Label the block Fruit Process.
Notice that gallons have automatically been selected as the flow units for the Valve. This is because it is connected to the Tank. (If you had not first connected the Tank to the Valve, you could select gallons as the units in the Options tab.)
To merge the two flows, add a Merge block to the model and place it to the right and between the Yogurt Process and the Fruit Process blocks.
Connect from the outflow connector of the Yogurt Pro- cess Valve to the top inflow connector on the Merge.
Connect from the outflow connector of the Fruit Process Valve to the second inflow connector on the Merge.
Fruit process line added
In the Merge tab of the block’s dialog, select Converge mode: proportional from the popup menu.
In the Proportion column of the Merge block’s dialog table, enter 9 for the Yogurt Pro- cess and 1 for the Fruit Process.
Label the Merge block Mixing.
Connect the Merge block’s outflow connector to the Yogurt tank’s inflow connector.
Discrete Rate

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