Sectioning is one of the most important – and historically most manual – steps in preparing a transient model in Impulse. Before running a simulation, every pipe must be divided into computational sections that align with the Method of Characteristics (MOC) solution approach. This ensures the model is solved accurately at each time step.
With the release of Impulse 11, that process just got significantly easier. The new Smart Sectioning Modes feature introduces automatic sectioning, allowing Impulse to determine the ideal number of pipe sections on its own, with no user input required. This enhancement streamlines model setup, reduces opportunities for error, and gives engineers more flexibility when they need it.
Understanding Sectioning in Transient Models
In transient analysis, the MOC requires each pipe to be divided into a number of sections so that the distance between calculation points corresponds to the time a pressure wave takes to travel that length. This depends on the pipe’s wavespeed and the time step of the simulation.
To produce accurate results, all pipes must share a common time step. That means the section length in each pipe must be a precise multiple of that time step. If not, the simulation becomes time-distorted and inaccurate.
Historically, Impulse calculated sectioning options but required users to review and confirm them through the Sectioning Panel in Analysis Setup. With Impulse 11’s new automatic sectioning, that step is no longer necessary.
Introducing Smart Sectioning Modes
Smart Sectioning Modes give users three distinct ways to define how their system is sectioned:
Each mode provides a different level of control, letting engineers balance accuracy and computational performance to match their needs.
Automatic Mode: Let Impulse Do the Work
With the new Automatic Mode, Impulse now determines the optimal number of pipe sections automatically, based on a defined Maximum Allowed Absolute Variance, which defaults to 10%.
In this mode, Impulse finds the smallest number of sections in the controlling pipe (the shortest in the system) so that every pipe in the model has an integer number of sections and stays within the acceptable variance. The software then applies a consistent common time step across the entire system – all without user interaction.
Automatic Mode eliminates the need to open the Sectioning Panel, review results, or confirm settings. The software simply applies the best sectioning scheme and runs the simulation. For most users, this means faster setup and fewer opportunities for error, while still ensuring that sectioning adheres to the MOC’s requirements.
Fixed Count Mode: Hands-On Control When Needed
For those who prefer more control, Fixed Count Mode allows the number of sections in the controlling pipe to be specified manually. This option behaves similarly to previous versions of Impulse but adds better visibility.
Users can now see exactly how their chosen section count affects the time step and maximum variance. This helps engineers make informed decisions about trade-offs between accuracy and run time. Since computational time increases roughly with the square of the number of sections, having clear feedback allows users to tune model performance efficiently.
Fixed Time Step Mode: A New Way to Define Precision
Impulse 11 also introduces Fixed Time Step Mode, a completely new capability. Instead of specifying a section count, users can now enter the desired time step directly. Impulse then determines the number of sections required in each pipe to achieve that time step.
This feature gives advanced users precise control over the timing resolution of a simulation, which can be especially valuable for analyses focused on event timing or control response. It provides another method to balance fidelity with computational cost while ensuring all pipes remain synchronized within the model.
Simplified Setup, Reliable Results
Smart Sectioning Modes represent a major usability improvement for Impulse’s transient simulation workflow. Automatic sectioning dramatically reduces the setup effort for most users, while Fixed Count and Fixed Time Step modes give experienced engineers the flexibility to fine-tune model behavior.
By automating a process that previously required user confirmation, Impulse 11 helps engineers build transient models faster, more consistently, and with fewer manual steps. The result is a smarter, more efficient workflow that maintains the analytical rigor engineers expect from Impulse.
Whether you prefer an automated experience or detailed control, Smart Sectioning Modes make it easier to achieve accurate results – letting you focus on solving engineering problems, not configuring calculations.