Ahmed, A transient simulation is an analysis of usually a few seconds (minutes) where you analyze the transient wave that is caused by a valve closing/opening, a pump turning off/on, a turbine starting/stopping, etc... An EPS simulation is an extended period simulation that analyzes the hydraulics of model over a period of time, usually in hours or days. This wiki should help answer the second part of your question: Basically, you will sort of always be using a steady state run for specifying your initial conditions, unless you otherwise use the setting for "specify initial conditions" in the Transient Solver calculation options. To clarify, if you run a steady state then the initial conditions are take from that information as a starting point for your transient analysis and if you run an EPS simulation then you need to clarify which time step of the EPS run that you will be using to set the initial conditions of the transient analysis by setting the "Initialize Transient Run at Time (hours)" property in the transient calculation options. Regards, Mark
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Forum Post: RE: Difference between running EPS and Transit for the same time period
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Forum Post: RE: What is the difference between the working phenomena of a vented vessel and air valve
Hello Ahmed, Is the vented vessel a hydropneumatic tank? If so, the two devices are quite different. The hydropneumatic tank can supply water to a system to help with transients that may occur. There is a "vented" option, which is effectively a sealed tank with the addition of an air valve at the top. This allows air at atmospheric pressure to enter the tank during a downsurge so that the device behaves like a one-way surge tank. During an upsurge, the air valve typically throttles the air outflow so that the gas within the tank is compressed and acts as a 'cushion' against transients (just like a sealed hydropneumatic tank). This device offers several practical benefits - for example since the tank typically has no gas inside, there is no need for compressors or a bladder to ensure a required gas volume is maintained. More information on hydropneumatic tanks can be found at the following link: communities.bentley.com/.../modeling-reference-_2D00_-hydropneumatic-tanks So while there is an air valve associated with the vented hydropneumatic tank, it will not function as an air valve. As for the air valve, this introduces air at negative pressures and releases the air again when the pressures increase. Details on how these work can be found at the following link: communities.bentley.com/.../modeling-reference-_2D00_-air-valves Regards, Scott
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Forum Post: RE: Difference between running EPS and Transit for the same time period
The key is that an EPS is just a series of steady state simulations; it does not account for what happens due to any change in momentum between those timesteps. A transient simulation on the other hand looks at what happens between two steady states - the effects from momentum changes. So, HAMMER needs to start with a steady state simulation and along with the configured transient event (the cause of a sudden momentum change such as an emergency pump shutdown, valve closure, etc) it simulates the transition from that starting steady state to a new steady state (if given enough time to settle on it). Establishing that starting steady state is the Initial Conditions, which is typically a simple steady state run. However since an EPS is just a series of steady states, HAMMER has an option whereby you can select a specific time step (steady state) from an EPS. See below article for more on that: communities.bentley.com/.../22786.how-can-i-model-a-transient-run-from-a-given-time-in-an-eps-simulation For more, I recommend reading the Help topic called "Hydraulic Transient Theory" or chapter 13 of our Advanced Water Distribution Modeling and Management book.
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Forum Post: Urgent Help needed For attached Sewergems Model
(Please visit the site to view this file)Dear Sir, Greetings!! I kindly request your urgent help in reviewing and fixing the attached SewerGEMS model. Please find below the issues for which the model needs to be fixed. We want to confirm if the pipes defined in the Conduit catalogue are taking part in the design; If yes, are the settings used correct. If not, does changing the settings in the model have any weird effect. Because we did some trial and error and found weird errors. I am sure you will provide us an easy fix and the guidelines on how to do it in proper manner. In the Default design constraint dialogue box, we have assigned velocities, slopes and cover as per local municipality criteria. Need your expert opinion on how these constraints effect on model – specially slopes. We would like you to confirm if the slopes defined are correct and behaving properly in the model? Please note that client has relaxed the maximum depth – At present we are getting 13.0 m depth at the principal pump station (PMP-8) from the attached model. Kindly note that model has 3 lift stations and principal pump station. We would like to confirm if this depth is applicable after your fix. Major issue in the model is the Velocities – we are not able to achieve self-cleansing velocities in 75% of the model pipes with the given design constraints. Just for your information we need minimum 0.70 m/sec velocity. We are not sure how the design priorities are being used based on the provided design constraints. We will appreciate some more guideline on this. I will appreciate your kind and quick help on this. Many thanks. Regards, Vivek Gupta
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Forum Post: RE: How the Sewercad transfers sanitary population after lift stations?
Hello Craig, Thanks a lot for easy fix. Cheers!!
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Wiki Page: Difference between EPS and transient simulation
Applies To Product(s): Bentley HAMMER Version(s): 08.11.XX.XX Environment: N/A Area: Modeling Original Author: Jesse Dringoli, Bentley Technical Support Group Problem What is the difference between an Extended Period Simulation (EPS) and a transient simulation in HAMMER? Solution A transient simulation typically spans a few seconds or minutes where you analyze the transient wave that is caused by a valve closing/opening, a pump turning off/on, a turbine starting/stopping, etc. An EPS simulation typically spans a matter of hours or days. The key is that an EPS is just a series of steady state simulations; it does not account for what happens due to any change in momentum between those timesteps. It essentially assumes that any transient effects have settled down to a steady state. A transient simulation on the other hand looks at what happens between two steady states - the effects from momentum changes. So, HAMMER needs to start with a steady state simulation and along with the configured transient event (the cause of a sudden momentum change such as an emergency pump shutdown, valve closure, etc) it simulates the transition from that starting steady state to a new steady state (if given enough time to settle on it). If the momentum change is severe enough, it can result in damaging high or low pressures and introduction of vapor or air. Establishing that starting steady state is the Initial Conditions, which is typically a simple steady state run. However since an EPS is just a series of steady states, HAMMER has an option whereby you can select a specific time step (steady state) from an EPS. See below article for more on that: communities.bentley.com/.../22786.how-can-i-model-a-transient-run-from-a-given-time-in-an-eps-simulation For more, I recommend reading the Help topic called "Hydraulic Transient Theory" or . See Also Help topic: "Hydraulic Transient Theory" Chapter 13 of Advanced Water Distribution Modeling and Management
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Forum Post: RE: Difference between running EPS and Transit for the same time period
This is now documented in the following Support Solution: Difference between EPS and transient simulation
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Forum Post: RE: Urgent Help needed For attached Sewergems Model
Vivek, thank you for bringing this issue on this forum. i hope we will get help from this forum. I have seen quite useful and prompt answeres from the bentley team especially Jesse.
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Forum Post: RE: SewerGems
Please see the help topic "Design Priorities" for details on the process used for automated design with the GVF Convex or GVF Rational solver. Also, you can refer to this article: communities.bentley.com/.../18162.what-is-the-order-of-the-design-priorities-used-in-stormcad-gvf-rational-solver-and-sewercad-gvf-convex-solver Further, using the search bar at the top of the Support Solution (wiki) section of the Hydraulics and Hydrology community, you can find several other articles on specific topics regarding automated design. If this does not help, please provide a copy of your model with some specific information. There are two options for sharing your model files on Communities. 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. communities.bentley.com/.../7079.be-communities-secure-file-upload
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Wiki Page: What's new in WaterCAD and WaterGEMS V8i SELECTseries 6?
Applies To Product(s): Bentley WaterGEMS, Bentley WaterCAD Version(s): 08.11.06.XX Environment: N/A Area: N/A Original Author: Mark Pachlhofer, Jesse Dringoli, Craig Calvin (Bentley Technical Support Group) Overview The SELECTseries 6 release of WaterGEMS and WaterCAD includes many new features and improvements. Let's explore each of these in detail. List of Topics Updated Platform Support AutoCAD 2015, 2016 ArcGIS 10.3.X ProjectWise with MicroStation CONNECT Edition SCADAConnect Ability to define custom SQL statements used to retrieve data Ability to add intermediate time steps for control overrides and fire flow demands New Find Element to Close option to improve pipe break analysis Main window enhancements for improved user experience Network Demand Calculator to easily reference summarized demands Flushing Improvements to flushing workflow New "Safety Factor" field to identify Recommended Flushing Volume/Time Streamlined selection and computing for flushing area or event Better user notifications Improvements in Flushing report Reduced to 2 pages instead of three Include Reopen, Reclose, Close (Prior), and Open (Prior) result options, based on the status of a valve in a previous event Ability to include prior-status rows to Event Elements table Improved results highlighting Quick pipe run creation tool Option to select boundary valves for flushing run Controls Performance improvement for large number of controls Easier creation of control sets when none exist Control set label presentation Easier managements of control sets, including display and filtering New "Find" function for easier control management Ability to import and export controls Tank Percent Full as a control condition Create control sets from selection FlexTables "Select in Drawing" for selected rows Create selection sets from selected rows Context Menu to quickly add or remove columns Open subset of rows through Right-click menu Freeze Column capability Sort arrow to indicate what is sorted and which direction Faster filter workflow with auto selection feature FlexTable text search Global Edit on selected cells Variable Speed Pumps (VSP) Overall improvement to VSP calculations including stability Improved headloss calculations in parallel VSPs Enhanced VSP validation for upstream/downstream pipes in parallel VSPs Improved handling for parallel VSPs when the lead pump is closed via a control New control action to modify "Pump Head (Target)" in VSP and VSPB Calculation Performance Multi-threading fire flow calculation Parallel linear solver for faster calculation Darwin Scheduler Performance Improvement Customer Meters Customer meters added to affected elements Customer meters have zone property Customer meter tab in pressure zone manager Other Bentley Communities Search RSS Feeds Pipe Renewal Planner Capacity Score headloss option Ability to control auto-open of Calculation Summary Easier export to Excel Flextables Several usability improvements have been added to Flextables: Freeze, Select, Add, Remove Columns The flextables have some very useful new features added. By right clicking on the grey column headers you will see the Freeze Column, Select Column, Add Column, and Remove Column options. Freeze Column – Will freeze that column and all columns to the left of it, so when you have a lot of columns in your flextable and need to scroll to the right you can freeze columns. For example, this is come be useful to keep a column like the label constantly visible for identification purposes as you access other columns. Select Column – Allows you to easily select all the records in that column, which is useful if you want to copy the data from that row to spreadsheet. Add Column and Remove Column – In previous versions in order to add or remove a columns, you’d need to click the edit button at the top of the flextable, but now you can easily select a property to add to your flextable through the add column option. When you move your mouse cursor over the add option a popup menu appears that breaks all the columns down by their category (general, physical, results, geometry, etc…). This makes finding properties much simpler than choosing from the entire alphabetized listed using the edit button in previous version. If you still prefer the using the edit button to add and remove your columns you will still have that option. Element selection by highlighting rows Another feature that adds great flexibility is the ability to select rows in the flextable by clicking on them. Rows are selected the same way you select them in an Excel spreadsheet. Once selected you can right click on the row header and choose “Open on Selection”. This will filter your flextable by the rows you’ve choose. This will allow you to perform tasks such as creating a selection set or adding to a selection set with more ease. It will also allow you to select the elements in the drawing that you have selected in the flextables. In previous versions both of these tasks would have to be done in the drawing pane or by using queries. The screen shots below show the process of filtering a flextable on row selection and show the menus for making selection sets and selecting elements in the drawing. While the flextable is filtered you now also have the option to right click and global edit on a column for only the features in that selection set. Sort arrow In the screen shot below you’ll see a small arrow has been added to columns that are sorted to indicated whether the sort is in ascending or descending order. Faster filter work workflow with auto selection When your right click on a column and choose to filter it using a query that column will now automatically be selected in the query builder to allow for faster queries to be created. In the screen shot below if you clicked on the diameter field outlined in blue and choose to filter by a query the diameter field in red would be automatically selected when the query builder opened. Find text in the flextable for faster feature location and selection Click the binoculars icon It will open this dialog that allow you to enter text to search the flextable based on Calculation Performance Multi-threading Fire Flow Calculation Have complete confidence in the improved speed, stability and robustness of the newly implemented multi-threaded fire flow calculation. The amount of parallel fire flow calculations can now be selected by going to Tools > Options > Engine tab. This improvement takes advantage of multiple CPU cores. Parallel Linear Solver for Faster Calculation Improvements have been made to the hydraulic solver to reduce processing time. Darwin Scheduler Performance Improvement Darwin Scheduler's performance has been improved. It now runs faster to provide better solutions for larger problems to optimize fixed speed single pump operation. Customer Meters Affected Customer Meters Listed in Criticality Results When computing a Criticality study, the affected customer meter nodes are listed. This allows a selection set to be created from the affected customer meters to quickly notify the users if needed. Customer Meters Have Zone Property Customer Meter elements now have the Zone property. This is useful for DMA's (District Metered Areas) and water audits. Customer Meters Added To Pressure Zone Manager The Zone Results in the Pressure Zone Manager now includes customer meters to show what zone they are in. Other Bentley Communities Search A "Search" button has been added to dialogs. Once clicked, a new tab will open in your internet browser and search the Bentley Communities wiki database using the name of the tool or manager it was clicked from. Click here to go to a support solution that explains how to search for content. RSS Feeds in Standalone Once you have been on the Be Communities website and created an account, you can sign up for RSS Feeds. On the Be Communities website, log in, then scroll down to the bottom and you will see, under Social Media, RSS Feed. The RSS Feeds dialog can now be opened from the help toolbar and from the help menu. Once you have signed up for the RSS Feed and chosen the subjects for your feed, when in WaterGEMS or WaterCAD, you can go to Help > RSS Feeds to see a list of the wikis and/or forums on your feed. Note: You must have a project open in order to do this. After you select RSS Feed a box will open with your feeds. You can do a search by typing a search term in the search bar, or you can do a filter by clicking on the filter button. If you click on the settings button in the upper right corner, a dialog box will pop up. Here you can select a product's feed. Pipe Renewal Planner Capacity Score Type The Pipe Renewal Planner capacity score can now be calculated based on either the headloss gradient or velocity. Prior to this release only velocity was used. Export to Excel The model's data can now be exported to Excel. Steps Go to, File > Export > Export to Excel. Then, in the Export to Excel dialog, specify properties and elements to be exported. Click OK. In the FlexTable Export dialog, select either Excel or CSV format and specify where it will be exported. Click OK See Also
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Forum Post: RE: What is the difference between the working phenomena of a vented vessel and air valve
Thanks Scott for your reply, But I am still confused. Does this vented hydropneumatic tank have an air valve above it ??? Then it is like a filled closed tank which could let only the air to come inside and outside the tank like the ordinary air valve. So what will be the difference ??
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Forum Post: RE: The total catchment area exceeds the total combined area. Select Series 4
Hello, You have a slightly older version of StormCAD. It is possible that upgrading may help with the issue. Steps on how to upgrade can be found at the following link: communities.bentley.com/.../8175.how-do-i-download-watergems-watercad-hammer-sewergems-sewercad-civilstorm-stormcad-pondpack-flowmaster-culvertmaster It that doesn't help, we will need to see a copy of the model to look into this issue. There are two options for sharing your model files on Communities. 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. communities.bentley.com/.../7079.be-communities-secure-file-upload If you upload the file to Sharefile, please post here with the name of the model so that we know it is available. Regards, Scott
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Forum Post: Collecting field data for WaterGEMS calibration - can't get pump data - which testing is still useful?
Question: Are hydrant tests and pipe roughness tests still useful if we can't get exact boundary conditions (pump data) at the exact time of the test? Background: We will be performing field testing soon to get data for calibrating a WaterGEMS model. I created a field testing plan that would require a massive number of people and time. Now I need to figure out what we can actually do with the time/resources available. The system has 4 tanks and 4 pump stations. The tanks are connected to the SCADA system, and we are told we can get water levels on them at any time we want. The pumps (and PRVs) are not connected to the SCADA system. Getting pressure/flow readings at the exact time of testing would require 4 people hanging out at the pump stations for hours, and those personnel are not available. It's possible we could assign one person to drive around to all the pump stations all day, making loops among the stations all day, and I think it would take 30 minutes just for the driving, plus time at each station to unlock/test/lock up. The city has 1-2 pressure gauges, and is willing to buy 3-4 more. Are there any recommendations for what to buy? I have been reading everything I can about calibration, and it seemed like doing fire hydrant tests and pipe roughness tests would be ideal, and that static testing may not give us much information. ***However, with the inability to get pump flow/pressure data at the exact time of the tests, would the tests still be useful? Or are they useless if we don't have exact boundary information at the time of the test?*** My plan: Calibrate equipment Do pump performance test at each pump to determine accurate pump curve Record flow/pressure at each pump station (4) [at beginning of each testing period/day] Record settings/pressures at each PRV (8) Take static pressure readings at various areas Perform fire flow tests at various areas Perform roughness tests at various areas Record flow/pressure at each pump station (4) [at end of each testing period/day] Given our constraints, is there any testing you would specifically recommend, or any you would recommend we NOT do? Tom Walski has sent me some calibration papers, which I will be reading this weekend.
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Forum Post: RE: What is the difference between the working phenomena of a vented vessel and air valve
Dear Scott, Sorry to bather you a lot, but I am facing some problems in understanding and resolving the model that I am working on.. The main problem in the model that it is for a deep Well water field , the pumps are installed 300 m below GL , the well field contain 80 wells and there is a network collecting the water from the wells and delivering it to the WTP. The main problem in this hammer analysis is the -ve pressure in pipes , there is no high +ve pressure. In my opinion , I must put as much as air valves to let the entrance of air to avoid the -ve pressure. If you do not mind I could send to you the hydraulic WaterCAD model to advice on the best way to avoid water hammer in pipes. If you do not mind please reply...
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Forum Post: RE: Collecting field data for WaterGEMS calibration - can't get pump data - which testing is still useful?
Katie, Not knowing if pumps are on or off will cause a lot of uncertainty in your calibration and can lead to what I call "calibration by compensating errors" where you use a wrong C-factor to compensate for the wrong pump status. It would seem that even in a system with no SCADA at a pump station, the utility would know when pumps are running. Do they have a paper chart recorder than normally reads 60 psi when the pumps are on and 45 psi when they are off. You can install a data logger at the station that you can hook into a flow meter. There are a lot of ways of know if a pump is running without having someone sit there looking at the pump all day. In some systems, you can just look at the level data for a tank. If the tank is filling, the pump is on. If it's draining, the pump is off. With regard to pressure gages, it's worthwhile to buy some good ones. Get at least a 4 in face, ANSI Type A or better (liquid filled is nice) and a full scale only slightly higher than the maximum pressure you expect (or several ranges). For example don't buy a $20 Home Depot gage with a one inch face and a 500 psi scale if all your pressures are less than 100 psi. You may also want to check out this You Tube video about flow tests and calibration. www.youtube.com/watch Best wishes, Tom
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Forum Post: RE: What is the difference between the working phenomena of a vented vessel and air valve
Hello Ahmed, The vented hydropneumatic tank does include an air valve, and at certain conditions will expel air from the system, just like an air valve. But a vented hydropneumatic tank does not act strictly as an air valve. It operates differently based on different conditions in the model, as explained in the previous post and can supply water to the system when needed. There is a sample model included with HAMMER that also has a scenario for a vented hydropneumatic tank: C:\Program Files (x86)\Bentley\HAMMER8\Hydropneumatic_Tank_Example.wtg. So a vented hydropneumatic tank is expected to act differently from an air valve. Regards, Scott
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Forum Post: RE: Collecting field data for WaterGEMS calibration - can't get pump data - which testing is still useful?
Thank you. So just knowing if pumps are on or off will be enough information to allow us to use the fire flow and roughness tests. I will find how if/how they know if pumps are on or off.
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Forum Post: RE: Customer Meter Element Associated Element
If I wish to use Darwin Calibrator to recommend some demand adjustments, how does doing this affect this? If I now have my customer elements associated with Hydrants.....??
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Comment on How can I use the customer meter element demands with Darwin Calibrator?
The link to the excel spreadsheet is no longer available.
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Wiki Page: Unable to meet minimum or maximum velocity constraint
Applies To Product(s): Bentley StormCAD,Bentley SewerCAD, Bentley CivilStorm, Bentley SewerGEMS Version(s): 08.11.03.XX Environment: N/A Area: Output and Reporting Subarea: Original Author: Mark Pachlhofer, Bentley Technical Support Group Problem Description No matter what I do I can't get the design run to be within the minimum or maximum velocity constraint that I have set. calculate below the maximum velocity that I have set. Why is this? Solution The maximum velocity is the very last design constraint in the priorities list (see article in "See Also" section below) and if you think about this makes sense. A higher velocity is really only going to scour your pipes more, which is usually just fine. In order to change the maximum velocity you'd have to change one or more of the other design priorties like the pipe diameter, minimum cover, maximum slope, etc... because you'd be violating the priorities list. In other words, the design tool assumes that the benefit of decreasing velocity does not outweigh the cost of up sizing the pipe or perhaps burying it deeper. Similarly minimum velocity is very low on the list of priorities. Adjustments to the pipe necessary to achieve a higher velocity may result in violating a higher priority constraint. If a design priority is violated a user notification alert for the element that violates it will be generated and you might need to make a need an engineering decision on whether this is going to be ok for your project or not. Manual adjustments are expected with the automated design tool because it's really just meant to give the engineer a good starting point for the project design. See Also What is the order of the design Priorities used in StormCAD and SewerCAD?
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