Hot Start File in SWMM
SWMM 5.2 UI
According to the Help in SWMM 5.2 UI
Hot Start Files are binary files created by SWMM that contain the full hydrologic, hydraulic and water quality state of the study area at the end of a run. The file saved after a run can be used to define the initial conditions for a subsequent run, producing the same results as if one continuous run were made.
Hot start files can be used to avoid the initial numerical instabilities that sometimes occur under Dynamic Wave routing. For this purpose they are typically generated by imposing a constant set of base flows (for a natural channel network) or set of dry weather sanitary flows (for a sewer network) over some startup period of time. The resulting hot start file from this run is then used to initialize a subsequent run where the inflows of real interest are imposed.
It is also possible to both use and save a hot start file in a single run, starting off the run with one file and saving the ending results to another. The resulting file can then serve as the initial conditions for a subsequent run if need be. This technique can be used to divide up extremely long continuous simulations into more manageable pieces.
Instructions to save and/or use a hot start file can be issued when editing the Interface Files options available in the Project Browser. One can also save the results of the current run to an abridged hot start file by selecting File >> Export >> Hot Start File from the Main Menu (not all state variables are available to be saved after a run has been made).
Currently we are not creating a hot-start file just using it the one's Caleb created. We have one for every rainfall.
The new files are running a little slow. to make sure it was not the hot start before reviewing the INP.
With Hot Start File Analysis begun on: Mon Nov 13 12:30:41 2023 Analysis ended on: Mon Nov 13 12:59:04 2023 Total elapsed time: 00:28:23
Without Hot Start File Analysis begun on: Mon Nov 13 13:05:57 2023 Analysis ended on: Mon Nov 13 13:33:00 2023 Total elapsed time: 00:27:03
For this quick test I am using Caleb's 2011Aug07T05 inp file. for the second test I commented out the hot-start instruction in the inp and ran it without it. Otherwise it was the same file. I will do this speed test in PySWMM as well.
Please note that the Simulated time is long for this run. The simulation starts on 7/8 and ends on 8/7 so it is 30 days instead of 48 hrs we have been running.
Hot Start and the inp file
The only modification for a hot Start is to the FILES section
