Defining Patterns
A pattern is a series of time step values, each having an associated multiplier value. During a dynamic analysis each time step of the simulation uses the multiplier from the pattern corresponding to that time. If the duration of the simulation is longer than the pattern, the pattern is repeated. The selected multiplier is applied to any baseline load that is associated with the pattern.
Patterns must begin and end with the same multiplier value. This is because patterns will be repeated if the duration of the dynamic analysis is longer than the pattern duration. In other words, the last point in the pattern is really the start point of the pattern's next cycle.
A dynamic analysis is actually a series of Steady State analyses for which the boundary conditions of the current time step are calculated from the conditions at the previous time step. This software will automatically convert a continuous pattern format to a stepwise format so that the demands and source concentrations remain constant during a time step.
An individual node can support multiple hydraulic demands. Furthermore, each load can be assigned any hydraulic load pattern. This powerful functionality makes it easy to combine two or more types of load patterns (such as residential and institutional) at a single loading node.
To define a pattern:
- Select Components > Patterns.
- In the Patterns dialog box, click the New button to create a new pattern.
- On the right side of the dialog box, enter values for Start Time and Starting Multiplier.
- Select Stepwise or Continuous in the Pattern Type field.
- In the time step points table, enter values for Time from Start and Multiplier. Drainage and Utilities validates your data as you enter it and displays errors and warnings in the status bar at the bottom of the Patterns dialog box. Be sure to check this status bar for any errors or warnings as you enter data.
- Perform the following optional steps:
- Click Close.
Patterns Dialog Box
You create, edit, and delete patterns in the Patterns dialog box. The dialog box contains a list pane on the left and several input fields and a table on the right:
The dialog box contains the following controls above the list pane:
The following fields and controls appear on the right side of the dialog box:
| Start Time | The first time step in the pattern. |
| Starting Multiplier | The multiplier value of the first time step point in your pattern. Any real number can be used for this multiplier (it does not have to be 1.0). |
| Pattern Type | Lets you select the type of pattern you want to create: Stepwise —The multiplier values are considered to be the average value for the interval between the specified time and the next time. Patterns using this format will have a "staircase" appearance. Multipliers are set at the specified time and held constant until the next point in the pattern. Continuous —The multipliers are considered to be the instantaneous values at a particular time. Patterns using this format will have a "curvilinear" appearance. Multipliers are set at the specified time, and are linearly increased or decreased to the next point in the pattern. |
The following controls are located above the time step points table on the right:
The time step points table contains the following columns:
| Column | Description |
|---|---|
| Time from Start | Lets you specify the amount of time from the Start Time of the pattern to the time step point being defined. |
| Multiplier | Lets you specify the multiplier value associated with the time step point. |
There is also a status bar located at the bottom of the dialog box that displays any errors and warnings that may occur when you enter data.