We’ve all experienced that fear. When we sit down at our computer and realize that all of our applications are closed. That Windows decided to do a restart in the middle of the night. If we are running any long simulations the thought of having to restart from the beginning is a tough pill to swallow. Luckily, in Flownex, we can use the backtracker functionality to create re-start points during the simulation. In today’s demo I am using the most recent Flownex release, 220.127.116.1175.
Enabling the Backtracker
The Backtracker is useful both for resuming long transients and for troubleshooting transient behavior around a transient action. The Backtrack setup can be found in the Configuration ribbon at the top of the Flownex GUI.
After clicking Backtrack setup we will see the backtracker pane available on the right side of the GUI similar to “Snaps”. We will want to click the floppy disk (save) button in the Backtrack pane to enable saving of backtracks. The button will have a blue outline when backtracking is enabled. The “X” button will delete all backtracks.
In the Backtracker interface we have several inputs we can define. The most important to define are the interval and the count.
- Defines how often a backtrack is saved. The default unit for interval is in seconds.
- Determines the count of recent backtracks that are retained in the Backtracker. If we want to capture the entire transient we should multiply the count by interval to make sure the entire duration is covered.
- “Use prefix number”
- This checkbox along with the “Start number” will save the backtracks with the desired number as a prefix, counting up with each concurrent backtrack save.
- “Use snap name as prefix”
- This checkbox will ensure that the backtracks saved have the prefix of whatever snap was loaded before the run was initiated.
- “Steps after snap load to first backtrack”
- This allows us to specify how many timesteps should complete (after initial snap load) before the first backtrack is saved.
Breath Easy and Run Transients
At this point we should be able to run our transient and see the backtracker populate. To load a saved backtrack point we should ensure our simulation is in an inactive state before right-clicking on the backtrack and choosing load. From this point we can resume our transient simulation.
- When troubleshooting a transient right-click on the backtrack just before the event and select “copy to snap” so that you can retain and load the state of the network at this start point.