I am trying to tweak some demands in my water model based on some suggestions that Darwin Calibrator is suggesting. I noticed that Darwin Calibrator is indicating a different original demand than the demand control center tells me and I'm confused as to where the value came from.
The active scenario is the same as the one that Darwin is using.
Any ideas?
tschrage,
What you need to do is click on where it you have "New Calibration Study - 1". From there you should be able to click on 'Field Data Snapshots' tab and check on the right side of the screen to see what the 'demand multiplier' (in the red box to the right) is set to. If it's anything other than 1 that is probably why your Original demands in the solution show as less than the value of your demands in the demand control center. If I had to guess I'd say your demand adjustment is set to about 0.72. Please see the screen shot below for where you should be looking.
Please let me know if that helps. If it doesn't please use one of the methods below to share your files. If you would like the files to be visible to other members, compress the files into a zip file and upload them as an attachment using the ‘Advanced Reply editor’ before posting. If your data is confidential, you can follow the instructions in the link below to send it to us via Bentley Sharefile. Files uploaded to Sharefile can only be viewed by Bentley.
Mark
Here a screenshot of my demand multiplier being set to 1. I will upload a copy of my model for someone to take a look at.
Can you let me know if the name of the file that you uploaded was the same as what is listed in your screen shot above, "2015 Water Model"? If it is then I don't see it in the folder where it should be. If you can upload the model files again I will download them and have a look. Regards, Mark
tscharge,
The first thing that you want to be aware of is that you are using the same representative scenario. In the case of the model that you sent this isn't what was happening and it caused some confusion. As you can see from the screen shot below the representative scenario is set to "Automated Fire Flow Analysis", but the active scenario in the model is "Automated Fire Flow - Test".
The confusion probably came because you were looking at the scenario drop down and there it looks like the "Automated Fire Flow Analysis" was the current scenario. It's not until you actually look that scenario manager that you see this was not the case.
I would suggest avoiding scenarios with similar names in order to try to prevent this from happening in the future.
After speaking with a few colleagues on this issue the confusion is based on what the "Original Demand" actually means in Calibrator. The original demand is not actually the original baseline demand for that junction that is listed in the demand control center, but rather the demand applied by the last field data set that was simulated.
With that stated what's important with the reported demand adjustment group results is not really the original demand value, but rather the multiplier applied to the original value. I can understand the need to know where the original value is being derived from, but try not to read more into it's usefulness other than being a starting point for the demand adjustments. The reason for this is because we could define the original demand value in a few different ways if we wanted. The original demand value could be an average of all the field data sets that you have or it could be simply be the baseline demand or it could be based on just the first field data set demand. This “issue” only applies to demands, since they can vary per field data set, where-as roughness and status have un-ambiguous original values that apply for all field data sets.
If you'd like to verify the calculations for yourself, which is why I'm guessing that you might have inquired about the original demand value, then you can do it this way. Take just one field data set and then check the "Original Demand" value. The value will be calculated as follows: Base Demand x Hourly Pattern Multiplier (for the time list on the field data set) x Daily pattern factor (based on the day the field data set was taken) x the monthly pattern factor (based on the month the field data set was taken). An example of this in your model would be work out like this (Using the Automated Fire Flow - test as the representative scenario): Take the field data snapshot for Hydrant 1453, which is the last snapshot in the field data set, and use junction 435. The base demand is 5.25 gpm and the pattern is called Diurnal. From the Diurnal pattern we see the hourly pattern factor would be 0.6 because the time this field data snapshot was taken was at 2:20 PM. The monthly multiplier should be 1.2 because the snapshot was taken in the month of June. The weekly pattern is 1, so we can omit that from the calculation. So 5.25 * .6 * 1.2 = 3.78 gpm, which is what you get for the Original Demand in calibrator and the Adjusted Demand. That said, the adjusted demand value would be the Original Demand * any demand adjustment factors that are applied to it. For a manual calibration run you enter these factors, but for an optimized calibration run Darwin Calibrator chooses this value from the allowable range of choices you provide it. These demand adjustments are entered on the demand tab in the demand multiplier column.
Please let me know if that helps.
Regards,
Answer Verified By: tschrage