| Product(s): | HAMMER |
| Version(s): | 08.11.XX.XX and higher |
| Area: | Calculations |
Problem
What do the HAMMER Calculation Option Reporting fields control?
What settings should be used in the Calculation Options Reporting fields to optimize performance (speed up / make the model compute faster) without compromising results? (and help prevent the reporting increment from being artificially increased as explained in this article)
Solution - Performance Improvements for Large Models
If you are working with a large model, it is strongly recommended that you use version 24.00.02.20 or higher, as a significant performance enhancement has been introduced. Additionally, improved calculation of friction factors for low flow pipes (common in large models) is also included.
Solution - General
If your model is large, it may be best to skeletonize (simply) first. See the following article for details on why: Preparing an existing model for a transient analysis in HAMMER
Also, consider a shorter simulation duration if you can capture the full transition between the initial and final steady states (or at least enough of the part where the worst transient pressure occur.) See: What should the run duration of a HAMMER model be set to?
Solution - Calculation Options
Here are the descriptions of the relevant transient calculation options. (Home > Calculation Options)
Calculation timestep:
Set the "Is User Defined Time Step" to "True" to specify a custom timestep, otherwise HAMMER will try to select a reasonable timestep:
You can use the Timestep Options dialog (Home > Time Step Options) to find a suitable timestep that prevent excessive adjustment to the pipe wave speed or length. If the timestep is too small, the model will take longer to run. Consider eliminating short pipes so a larger timestep can be used.
See: Understanding length/wave speed adjustments and their impact on results
Generate Extended Output Log?
When the value is true, the output log includes additional information for every node, such as the flow, head, and vapor/air volumes at the first, second and last time steps.
To open the output log, go to the Report tab and select Analysis Output Log.
This setting will not make a significant impact on the time it takes to compute.
Show Pocket Opening/Closing?
Toggles whether the list of vapor pockets open and close times will be appended to the output text file.
To open the output log, go to the Report tab and select Analysis Output Log.
For Example:
The cavity at node "Air Valve" opens in 3.31 seconds.
The cavity at node "Air Valve" closes in 12.90 seconds.
This setting will not make a significant impact on the time it take to compute.
Generate Detailed Reports?
Toggles the generation of ASCII output text files on or off. These can become voluminous for simulations with many time steps and they are not required for the operation of the FlexTables or graphics. Some users prefer to set this setting to False. When this is set to true the generated report can be viewed by selecting the Report tab clicking Analysis Detailed Report.
Report Point History Type
Select All to generate point histories for all points in the text reports, or Only if On Path to generate report Histories only for those points that lie on a path.
Computing time will be lower when Only if on Path is selected.
Report Points
Specify whether to report results on All, Selected, or No points.
This controls the points that are computed and available to have their Time History plotted in the Transient Results Viewer.
Compute time will increase with the amount of points being reported. For optimal performance, it is recommended to set this to Selected. Then only include points you want to see the time history for.
Note that the list of report points in the dropdown in the Time History tab of the Transient Results Viewer cannot currently be sorted. The related Enhancement request is 903576. Using the Report Points option to filter down to only the notable locations will help establish a more manageable list.
Report Points Collection (available when Report Points is set to "Selected Points")
Clicking the ellipsis button in this field opens the Report Points Collection dialog, allowing you to choose the report points from the list of available points, or select them in the drawing.
See: How do you select only certain report points in the transient calculation options?
Report Times
Choose whether to report Periodically, At Specific Times, At No Times, or At All Times.
It is recommended to set this to "At All Times" to prevent the behavior in this article.
See Also
How do you select only certain report points in the transient calculation options?
Transient maximum result is different from the highest value seen in a time history graph
Preparing an existing model for a transient analysis in HAMMER