How to model time history on a piping system with branch piping?
Example:
Given the piping arrangement below, how to correctly apply a fluid transient from start point (ex. B04) to Tee location (ex A05) and in both directions to the anchors (ex. A00 and A10),
Figure out how long it takes the fluid transient to go from the start point (ex. B04) to the junction point (ex. A05) where the transient will split in 2 directions.
Using the Fluid transient dialog enter data for fluid, start location, split location and flow rate:
Pressing OK button will display the associated THL file.
Note: this transient will not be used in the analysis, it was only a tool to help determine the time which is required by this modeling approach.
From the THL file find the time it takes the transient to travel from the starting point along the pipe to the split point.
Time = .002331 sec
In this model there will be 2 transients:
Transient #1 will start at the beginning and proceed down to the junction point, at which time it will continue down one of the branch lines to the end.
Transient #2 will begin at the intersection point st the precise moment the transient reaches that location and will continue to the down the other branch line to the end
Set up Transient #1:
Note: each time there the transient changes segment a new line must be added to the transient (ex. A05 - A00).
Set up Transient #2:
Note: start time was based on the time calculated in step #1 above (ex. .002331 sec).
Since the model is symmetric stand to reason that the transient should have reached the anchor points (ex. A00 and A10) at the same time. From the THL file see that this is indeed true, "Time at the end of Fluid transient" value is exactly the same for both (ex. 0.005944 sec).
Finish adding the Fluid transient load on the Time History tab of the Dynamic Analysis dialog:
Notes:
1. currently a single transient load case (M1..M50) can only have 4 files associated with it.
2. Use same technique described above to add fluid transients end to end. Just need to set the start time of the successive wave at the precise moment the initial transient arrives at that point.
AutoPIPE can model a fluid transient from a start point to an end point. The program is also capable of modeling transients on branch locations along the path of the initial transient.
Dynamic "Time History" Analysis
Bentley AutoPIPE