Hello, I am currently trying to set up a simple private fire man with a reservior, a pump and a fire hydrant. Since there is no downside reservoir, I set up a pressure dependant demand for the hydrant. I am currently running a steady state. My elevations, pipe sizes, minor losses and demand for the hydrant are all set. My question is, how can I generate a system curve, without having to define the pump first. Any ideas? Thank you
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Forum Post: System curve with no pre-defined pump.
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Wiki Page: How to control the display of Active Topology for elements on the ArcGIS/ArcMap Platform?
Product(s): WaterGEMS, SewerGEMS, HAMMER Version(s): 10.XX.XX.XX and 08.11.XX.XX Area: Layout and Data Input Problem Description How to control the display of Active Topology for elements on the ArcGIS/ArcMap Platform? Background The display inactive topology setting for Bentley products (WaterGEMS, SewerGEMS, HAMMER) in ArcMap works differently than it does in the standalone products. In standalone, when an element is set to be inactive, it will display as configured in the Options menu (Tools > Options > Global tab). When using these Bentley products in ArcMap, with the default configuration, setting elements to be inactive will only toggle the Is Active attribute in the GeoFlextable. Resolution There are two ways to view and edit the display of active topology for elements in the ArcGIS/ArcMap platform. Option 1 - Use the Bentley Product's Renderer Enable "Apply [Product] Renderer" and "Auto Refresh". To enable these settings, open the "Bentley [Product]" menu, select View and select each setting. A checkmark next to the setting indicates it's enabled. To control how inactive elements display in the drawing view, open the Bentley [Product] menu, select Tools, and click Options. In the Options dialog, select the Global tab. Unchecking the box next to Display Inactive Topology will remove inactive elements from the drawing and the box to the right controls the color inactive elements will display with. Option 2 - Use ArcMap's Layer Symbology Notes: The steps below will need to be completed for each Layer (ie. element type). The symbology defined using this method will not be applied when "Apply [Product] Renderer" is enabled (Bentley SewerGEMS/WaterGEMS/HAMMER > View > Apply SewerGEMS/WaterGEMS/HAMMER Renderer). Steps: In the ArcMap table of contents right click on a layer, and select Properties. on the pop up dialog box and click on the Symbology tab of the layer properties dialog. In the Layer Properties dialog select the Symbology tab, click on Categories in the left pane and select Unique values. In the Value Field dropdown menu select Is_Active and then click Add All Values. After doing this, and two new symbols should appear (0-Inactive, and 1-Active). Uncheck the box next to to remove that unnecessary value from the Table of Contents dialog. To change the icon and color that the inactive and active elements will display with, double-click in the symbol column next to the corresponding value. To prevent inactive elements from displaying, set the color to No Color. Repeat this process for each layer (ie. element type). Make sure to select Apply and OK to save the changes. See Also Active Topology Management
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Forum Post: RE: Flowmaster open channel analysis issue
Thank you for the reply! I had a typo there. I meant 0.03 as the Mannings n. My task is to compare discharge with a different cross-sections of open channels ( with the same area ) ,and also compare the results from the different methods. I am given that the n=0.03 bottom width =0.7m slopes are 1 m/m normal depth is also 1m and channel slope is 0.0004 m/m And the result I am looking for is discharge (m3/s) Ill also add the two photos for examples. When I first saw that the results differ ~2 times, it was really counter intuitive, as I would expect them to be atleast relatively close if all of them can be applied to real life situations. Seems like there would be no point of using one of them if it gives out the result which is so far off from the one in reality. But then again, Im just a student trying to figure this out.
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Wiki Page: Perform unit conversions with FlexUnits
Product(s): FlexUnits Version(s): 02.01.00.04 Area: Calculations Problem How can I easily perform unit conversions for virtually any dimension type including flow, length, velocity, viscosity, area, volume, torque, temperature etc. Solution Bentley FlexUnits is a handy tool that makes unit conversions quick and easy. To Download (Free): Click here and selecting "Download Now" on the lower-right. You must be signed in to download. It can also be downloaded using the steps provided in this article . Note: You can add, edit, and remove your own dimension types and units. Unit conversions can include offsets as well as multipliers. This is helpful for dimensions like temperature, where not every scale shares the same zero value. The log at the bottom of the application helps you remember and reuse unit conversions you perform. See Also Hydraulic Calculator Software Downloading Haestad / Hydraulics and Hydrology Software
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Forum Post: RE: Flowmaster open channel analysis issue
Sorry, forgot to upload the screenshots
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Forum Post: Multiple VFD pumps in parallel controlled by the pressure at the same downstream node. NOT WORKING
First off, I am using WaterGEMS Connect, 10.2. These three pumps are in parallel, have the same curve, and are controlled by the pressure at the same downstream node. ownstream of these pumps are 4 other pumps that are driven by the HGL in water towers downstream of them. Two of the three VFDs have ON/OFF controls based on the same tower. The controls for the two controlled VFDs are identical to those for the first two on and last two off for the downstream pumps. (I initially had it such that if Pump A was on Pump X was on, and if Pump B was on Pump Y was on, but that left a lag between where pressure in the first system dropped negative). Now, the two controlled VFDs turn off before they should according to the controls, and don't come on until the controlling tower is well below the control point, then the other two switch on at once, then all three immediately switch off. Can anyone provide helpful guidance for using parallel VFDs that is understandable for someone who has never used them before?
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Forum Post: RE: System curve with no pre-defined pump.
Hello Nick, As mentioned by Dr. Walski, you need to enter first pump definition to get system head curve. Here is detailed information about system head curve, for your reference. To calculate the system head curve, WaterGEMS/WaterCAD needs a pump curve entered against which it can show you how the system is behaving, based on which you can make changes in the pump definition if required. Understanding system head curves The below technote talks about how to calculate the pump curve, if you haven't done so already. Estimating a pump curve for a model
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Forum Post: RE: Multiple VFD pumps in parallel controlled by the pressure at the same downstream node. NOT WORKING
Hello Mike, Model in this case will help to understand situation, please upload model files for our review. Sharing model files
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Wiki Page: Differences between solvers: GVF-Convex vs. GVF-Rational vs. Implicit vs. Explicit (SWMM)
Product(s): SewerGEMS, SewerCAD, CivilStorm, StormCAD Version(s): CONNECT Edition, V8i Area: Modeling Problem What are the differences between the SewerCAD (GVF Convex Solver), SewerGEMS/CivilStorm (Implicit and Explicit Dynamic solvers), and StormCAD (GVF Rational Solver)? When should I use StormCAD instead of CivilStorm? Solution The SewerCAD GVF Convex solver uses convex routing and a gradually varied flow profile for design and analysis of of sewer networks including mixed gravity and pressure flow. SewerGEMS is a superset of SewerCAD, including all its functionality, plus two fully dynamic solvers (Implicit and Explicit) and ArcGIS integration support. SewerGEMS Sanitary was a separate program included with older versions of SewerGEMS V8i (08.11.01.21, 08.11.02.46, 08.11.02.49 and 08.11.02.75). It is installed automatically when installing these versions of SewerGEMS and includes all the functionality of the Bentley SewerCAD product, plus the ability to work inside of ArcGIS. As of SewerGEMS V8i SELECTseries 3 (08.11.03.77+) SewerGEMS Sanitary is no longer available with this specific brand name because of the conversion of all of our storm and sewer products into a unified file format. The unified file format now allows all the storm sewer products (StormCAD, SewerCAD, SewerGEMS, CivilStorm, and SewerGEMS) to open a model created in another product. In creating the unified schema SewerGEMS has been changed to incorporate all the storm sewer solvers, so if you want to run the SewerCAD solver (GVF-Convex) on your network you have the option to. This is really the same thing as having SewerGEMS Sanitary come with SewerGEMS, except you no longer need to open a separate program, and you also have the option to run the GVF-Rational (StormCAD) solver for your model if you choose. In other words, With the SewerGEMS SS3 release Bentley accomplished a convergence of SewerGEMS Sanitary modeling fully into SewerGEMS. As a result SewerGEMS embodies effectively a superset of the capabilities delivered in StormCAD, CivilStorm, SewerCAD, and SewerGEMS. All consolidate into a common data store. All differentiate by the computational solvers that are selectively packaged into each product in service to a range of commercial use-cases across stormwater, sanitary, and combined systems. With this release SewerGEMS Sanitary was deprecated. It was cleanly folded into the SewerGEMS application. How do I know which solver is best for me to use? SewerCAD (GVF Convex) vs. SewerGEMS (Implicit and Explicit) The SewerCAD application (and the GVF Convex numerical solver in SewerGEMS) is best used in systems that have complicated pumping, pressure sewers, and only need to use extended period simulation convex (EPS) routing as opposed to fully dynamic routing. SewerCAD should also be used if you need to perform a constraint-based automated design or if you need to run a steady state simulation, such as for a peak flow analysis with Extreme Flow methods. SewerCAD can be thought of as a bread-and-butter package that delivers conventional design and capacity analysis. Municipal-scale master planning is certainly part of it, but serves very well in site/civil arena as well. Routing is hydrologic with conventional back-water dominant hydraulics. Gravity analysis is complete with well-accepted state-of-the-practice hydraulic grade analysis with form losses. Diversions or splits are handled in explicit ways. I&I, similarly, is modeled using an array of fundamental and appropriate simplifying models. On the other hand, the SewerGEMS/Civlstorm applications layer into the mix solvers for dynamic wave simulation (implicit and explicit (SWMM), with ArcGIS integration support. So, if you have challenging cross-connections, loops or dynamic surcharging and ponding, this gives you the capabilities of EPA SWMM along with Bentley's own implicit solver. SewerGEMS (Implicit or Explicit Dynamic numerical solvers) is best for analyzing existing problematic systems, where catchment rainfall-runoff calculations are required or dynamic wave solutions are needed (if required by the reviewer or by way of the complicated nature of the particular network) or if you must work inside the ArcGIS platform. SewerGEMS can handle complex things like control structures, diversions (without having to enter a diversion rating curve required in SewerCAD/GVF Convex solver) or ponds. Long term continuous simulations would be done using the Explicit solver in SewerGEMS. The "solver" refers to the type of numerical finite difference solution used to solve the St. Venant equations, which describe unsteady one-dimensional, free surface flow. The software contains two different solvers:: Implicit solver - Uses a four-point implicit finite difference solver to find the numerical solutions for the hydrodynamic Saint-Venant equations. This solver is based on the National Weather Service FLDWAV model. The implicit solver tends to be more stable with pumping situations. Explicit (SWMM) solver - Uses the solver from the EPA Stormwater Management Model version 5 (SWMM). The results from this solver should exactly match the results from SWMM 5. The explicit solver tends to be more stable with fast changing areas such as ponds or control structures where the flow or elevation changes quickly over multiple time steps. There is an initial elevation attribute for manholes using the SWMM engine so that the calculation can simulate a filling process if the initial elevation is lower than the downstream start elevation. However in the Implicit engine the manhole initial elevation is not considered, so the initial manhole elevation is assumed to be the same as the downstream start elevation. Inflow hydrographs are also handled differently by the two engines. The implicit engine interpolates flows between the final flow in the hydrograph and the end time. The SWMM engine assumes that all flows after the final inflow point are zero. *Note: If a catchment is using the EPA SWMM runoff method and not using the default infiltration method specified in the SWMM calculation options then neither hydrology or network will calculate. If you are not using the EPA SWMM runoff method, then any combination of other runoff methods can be used. GVF-Convex (SewerCAD) solver is not intended to handle overflow situations such as a case where you want to analyze a problematic existing system. When an overflow condition arises with the GVF Convex solver, the HGL is reset to the rim for an overflow condition. However, the dynamic solvers in SewerGEMS (Implicit and Explicit SWMM solvers) do handle overflow, as they are intended for situations like this (problematic existing systems and/or complex situations). SewerGEMS Implicit and Explicit solvers automatically calculate the overflow using the weir equation. So, SewerGEMS differentiates in the market as being a singular, "top of the line" tool that will carry the engineer though all stages of design and analysis from conventional capacity and automated design of pipe networks into complex hydraulics of combined-sewer systems. SewerGEMS will handle both storm and sanitary models. Importantly, if you have any old StormCAD, SewerCAD or CivilStorm files they can all be loaded into SewerGEMS and brought cleanly ahead. The GVF Rational Solver Note: Currently the StormCAD numerical solver is included with CivilStorm, so CivilStorm has all of the functionality of StormCAD included, by way of selection of GVF Rational as the active numerical solver. The StormCAD product (and the GVF Rational Solver in SewerGEMS and CivilStorm) uses the rational method to analyze or design a system under peak flow conditions based on peak rainfall intensity, while the other solvers in CivilStorm and SewerGEMS such as the Implicit or Explicit, takes rainfall hyetographs (rain vs. time) and develops hydrographs (flow vs. time) for each pipe and routes the flows dynamically. If you are studying a small area where only peak flow is of interest, or if you need to design a system based on the standard rational method, then StormCAD or the StormCAD solver (GVF Rational) should be adequate. If you are working on a large area where hydrograph routing and storage are significant, where you need to use a dynamic solver, or if you need to otherwise analyze more complex effects such as flooding and controls structures, then the Implicit and Explicit solvers in CivilStorm (or SewerGEMS) is what you need. If you get involved with combined sewers where rain and sanitary sewage is carried in the same pipe, we recommend you use one of the dynamic solvers in SewerGEMS. See Also StormCAD FAQ SewerCAD FAQ SewerGEMS FAQ Conduit start/stop control structures
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Forum Post: RE: WaterCAD - ModelBuilder / Import of Sub-Model - Limitations
Hello Yashodhan, Thank you for your response. I appreciate your attempt for further investigation. Kindly provide your feedback as early as possible, since I am having an upcoming meeting with our client, where I would like to clarify this issue. Best Regards Florian
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Wiki Page: Using Multi-Species Extension (MSX) for advanced water quality modeling
Product(s): WaterGEMS, WaterCAD Version(s): 08.11.XX.XX, 10.XX.XX.XX Area: Modeling This technote will talk about how to setup Multi-species analysis which is advanced part of Water Quality Modeling, in which cases multi-species modeling should be used and its references. Background Using constituent analysis, a user can track a single constituent through a water distribution system, provided the constituent behaved according to one of the kinetic models (e.g. first order decay). However, some constituents (E.g. Multi-source chlorine decay) cannot be modeled this way because they are involved in significant multi-species reactions or their kinetics do not fit one of the existing models. To handle these cases, WaterGEMS provides Multi-species Analysis, based on the EPANET-MSX model with a WaterGEMS user interface. Multi-species analysis allows for consideration of multiple interacting species in the bulk flow and on the pipe walls. It can be accessed through For V8i, Components>Multi Species analysis setups. For Connect Edition, Components>Water quality>Multi Species analysis setups. Workflow To perform a multi-species analysis, You should set up Multi Species analysis setup in the components. You could import existing setups from engineering library. Create a new scenario and calculation options, if required as you would do for water quality analysis. For Connect Editions, Go to Analysis>Options>Calculation type>Multi Species Analysis. For V8i versions, go to Analysis>Calculation options> Calculation type>Multi Species Analysis. Select Multi Species analysis setup, the one you created earlier or edit Multi Species analysis setup to create a new one. Calculations The time step for calculations that is used in the multi-species analysis is the one which is defined in the OPTIONS setup of the Multi Species analysis. If it is not defined in the options of Multi Species analysis, then the default water quality time step is used which 1/10 th of the hydraulic time step. NOTE : For detailed information on Multi Species analysis and Multi Species analysis model configuration, please look at the help documentation. Reference : More information about Multi Species analysis can be found in the EPA MSX manual. EPANET Multi-Species Extension Software and User’s Manual See Also Mixing Chlorine and Chloramines Understanding the Water Quality Time Step Modeling DBP Formation - Water Quality Analysis
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Wiki Page: Can HAMMER report the velocity of air through an air valve?
Applies To Product(s): HAMMER Version(s): CONNECT Edition, V8i Area: Modeling Original Author: Jesse Dringoli, Bentley Technical Support Group Problem Can HAMMER report the velocity of air through an air valve? Solution No, HAMMER currently doesn't report the air flow velocity, however, the air flow rate can be computed using a function in Excel. To see a table of air volume, head, air mass and air outflow rate over time, enter a number for the "Report Period" field in the properties of the air valve, re-run the model, then look at the bottom of the Transient Analysis Detailed Report (located under Reports > Transient Analysis Reports). You can copy/paste that table into another text file, then use the data import feature in Excel to bring it in. Another option would be to place the air valve node at a "tee" from the main pipeline. You will likely need a smaller timestep to avoid excessive length adjustment in the short lateral pipe, but then you'll be able to graph velocity in the time history tab of the TransientRresultsVviewer, for the pipe adjacent to that valve. It is important to note that this is the velocity of the water column as it moves away from the air valve opening (for air inflow) or toward it (for air outflow). When dealing with an air valve, there are two flow rates (and two velocities) one for the "free air flow" at the air valve opening and the other for the air flow at pipeline pressure. The difference is due to the difference in air density as the air pocket can be compressed. The air flow rate reported in the aforementioned detailed report is also the flow at pipeline pressure (inside the air valve). See Also Modeling Reference - Air Valves
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Forum Post: RE: Flowmaster open channel analysis issue
Rihards, FlowMaster uses the standard equations for the respective roughness methods so its calculations can be validated from a hand calculation of those equations. I think the key here is that these roughness methods are different and use different coefficients. So, it can be difficult to determine equivalent coefficients between the different methods. Although the Material Library entries may be a good estimate for a reasonable coefficient for each method, they are just one possible reference, and the corresponding coefficients for the different roughness methods may have been developed using different flow conditions. When comparing a given channel at a given slope and flow depth, the "equivalent" roughness coefficient may change. For example I achieved a flow of exactly 1.70 m^3/s for each of the three roughness methods when using a Mannings n of 0.0123, Hazen-Willians C of 128 and Darcy-Weisbach e of 0.00043 m. However, if the normal depth is increased from 1 to 9 m, the corresponding flow was off by as much as 15%. This illustrates how these friction methods are different and the sensitivity to the roughness factors. In the US, typically for open channel, the Mannings method is used almost exclusively, whereas for pressurized water pipes, the Hazen Williams equation is used almost exclusively. So, it may be a matter of choosing an appropriate method based on the local standards, then selecting an appropriate coefficient from the library or from another reference or standard. You may want to seek scholarly articles on these different roughness methods and/or their application for open channel flow.
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Forum Post: Pipe profile from Transient Analysis suddenly dropped
Hammer is reporting an error stating that "Profile not included - A pipe in the Profile was dropped". The model previously ran fine and all I've done is to add a new pump definition for a higher flow - but now have this error message. Hammer also wont 'zoom to' either, under the user notifications, as I presume the software can't now see the pipe its dropped? Stuck to know how to resolve and why this is happening? Can anyone assist?
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Forum Post: RE: System curve with no pre-defined pump.
Additionally, the following articles cover the general pump selection process: General Pump Selection Process Pump selection for a closed system
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Forum Post: RE: SewerGEMS in ArcMap - Disappearing Fields
Hi Jesse, thank you for the reply. Since posting this, I've had a couple of developments. I do believe there was an issue with the connectivity of my mxd file and my model mdb file. This morning I reopened my mxd and received the following Microsoft .NET warning: "Unhandled exception has occurred in a component in your application. If you click Continue, the application will ignore this error and attempt to continue. Object reference not set to an instance of an object." It appeared I could not open my model, and that somehow the link was broken. I ended up detaching the model file altogether and re-attaching it through a new .mdb file. Somehow the link was corrupted, and I'm not exactly sure why. This could have been the source of my issues with the attribute fields not matching my geotables. I also noticed that under Tools > Database Utilities, there is an option to Synchronize Drawing. Would that work to update the attribute tables correctly? Also, are there any measures I should take so that the link isn't broken between my mxd and model again? Another piece of information is that I am running the 10.00.00.40 version of SewerGEMS within version 10.5 of ArcMap. and I saw on the compatibility table that I should need a newer version of SewerGEMS. Would that be a potential source of error as well? Thanks!
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Wiki Page: Modeling Reference - Valves
Applies To Product(s): HAMMER, WaterGEMS, WaterCAD Version(s): V8i, CONNECT Edition Area: Modeling Original Author: Jesse Dringoli, Bentley Technical Support Group Overview This technote explains how various types of valves work and their typical application in HAMMER and in WaterGEM / WaterCAD. It also provides an example model file for demonstration purposes. Primary Valve Elements The main "valves" icon on the layout toolbar offers several generic valves: GPV, TCV, FCV, PRV, PSV and PBV. These are sometimes collectively referred to as "valves of various types" in older versions of HAMMER. These valve elements serve various purposes and are frequently used in steady state or Extended Period hydraulic models. They can generally be categorized as flow control. For example, the GPV defines a curve of flow versus headloss, the FCV (Flow Control Valve) controls flow to a set point and the PRV (Pressure Reducing Valve) controls the downstream pressure to be below a set point. The important thing to understand about dynamic valves like FCVs, PSVs and PRVs is that their controlling effects (pressure reduction, flow control, etc) only apply to the initial conditions calculation (steady state or EPS). For a given steady state or EPS timestep, a specific headloss occurs across the valve. For example, in order for the PSV element to sustain upstream pressure, a specific headloss occurs through the valve, such that in order to balance energy across the network, the upstream hydraulic grade ends up being higher than the PSV set point. During the transient simulation, a discharge coefficient is calculated based on that valve's headloss during the initial conditions timestep. Note: the following equation is used to convert between headloss coefficient and discharge coefficient: H = 39.693 * D^4/Cv^2 Where: D = Diameter (ft), H = Headloss coefficient (K), Cv = discharge coefficient (cfs/ftH20^0.5) It can be re-written as: Cv = ((39.693 * D^4) / H)^0.5 As the transient simulation progresses and the system conditions change, these valves will not automatically react, like they do during the initial conditions. Meaning, if the transient conditions cause a higher flow through a FCV, it will not automatically throttle (change its headloss) to react accordingly. The reason is because HAMMER assumes that these valves cannot react fast enough during the transient simulation. So, they will stay in a fixed position based on the aforementioned discharge coefficient from the initial conditions. However, the user can manually open and close these valves during the transient simulation by using the Operating Rule. The operating rule is an attribute of the valve, found under the "Transient (Operational)" section of the properties. It allows you to define a pattern of Time versus Relative closure, to be using during the transient simulation. Note: PRVs are currently an exception to this, as they have the ability to modulate (throttle automatically to meet a setpoint) during the transient simulation. See related article: Using Modulating PRVs For example, if you have a gate valve that is fully open in the initial conditions and you want it to fully close during the transient simulation, you could define your operating rule with a starting relative closure of 0% and pattern that rises to 100% at some point. You would then select that in the valve's properties, under the "Operating Rule" field. You can analyze the effect of various closure patterns either by manually changing the operating rule and re-running the simulation or by creating multiple scenarios, computing a batch run in the scenario manager and then individually examining the transient results. Note: The operating rule designation is stored in the "Transient" alternative. Generally the transient surge will be more severe for a faster closure. So, typically the last bit of closure should occur slowly. For example, the valve may close quickly between 0% and 95% closure, then slowly close for the last 5%. However, you may want to analyze the worst case scenario where the valve is closed too quickly. The speed of closure can easily be reflected in your Operating rule pattern. Note: Do not confuse the Operating Rule with the "Pattern (Valve Settings)" or "Pattern (relative closure)". The latter two fields may be found under the "physical" section of the valve's properties and are used to establish a manual closure pattern for the valve during the initial conditions (EPS) only. For general valve closure purposes such as gate valves, isolation valves, etc, it is recommended that you use the TCV valve type (throttle control valve). This valve represents a standard headloss or discharge coefficient during the initial conditions. So, in the above example of an initially open valve, you would specify the loss coefficient representing the losses through the fully open valve. Other Valve Types Valve with Linear Area Change - The "Valve with Linear Area Change" element represents a simplified valve that either closes linearly (with respect to area) or acts as a check valve that stays closed upon reverse flow. The user only specifies a time to close, so no delay can be incorporated with the closure. Meaning, it starts closing as soon as the transient simulation begins. See more here: Modeling Reference - Valve With Linear Area Change Pump valves - The pump element has a built-in valve, that can either operate as a check valve (when the "Pump Valve Type" is set to "check valve") or a linearly closing valve (with the "Pump Valve Type" set to "Control Valve"). The Control valve will either open or close over a given duration, depending on the initial status of the pump (on or off). See also: Modeling a pump that has neither a check valve nor a control valve Check valves - a check valve can be simulated in a pipe, as a separate node element, and built into a pump. These close upon reverse flow. A slow closing operation can be modeled with the check valve node element. More on this here: Modeling Reference - Check Valves Isolation valve - this element can be associated with the pipe, so it has the benefit of not adding an extra pipe from a split. However, the operation of this type of valve cannot be simulated during a transient simulation. Meaning, it can only be used to set the initial status of the related pipe to open or closed. If you need to control an isolation valve, use the TCV element instead. Initially Partially Closed Valves The TCV also has the ability to model the opening/closing of a valve that is initially partially closed. This is done by way of the "valve characteristics curve" coefficient type and "Valve Type". Normally, the discharge coefficient that the program computes based on what the valve is doing during the initial conditions is interpretted by HAMMER as the fully open position. For example, if you use a GPV, the headloss calculated through it in the initial conditions is always interpretted as a relative closure of 0%, even though in reality, it may be partially closed. This can cause confusion when defining the operating rule. However, with the valve characteristics curve coefficient type for a TCV, the user can define the relationship of discharge coefficient versus relative closure; therefore, a partially closed valve can be properly modeled. Detailed instructions on how to do this are beyond the scope of this technote. For more information, please see Modeling An Initially Partially Closed Valve Custom Valve Characteristics By default, several standard valve types are available, in the "valve type" field (such as butterfly, globe, needle). This essentially defines the discharge coefficient that HAMMER uses for various values of "relative closure" in the operating rule. For example, some valves may have a sharp reduction in area as they start to close (stroke) and then a slower reduction in area just before they are fully closed. Meaning, a value of 90% closure in your operating rule might not necessarily mean the valve's open area is 10% of the original area. The user can also define a user defined table of relative closure versus relative discharge coefficient, by selecting "user defined" as the valve type. This exposes the "Valve Characteristics" attribute, which is where you would enter the table of relative closure versus relative discharge coefficient to define the characteristics of your valve. The relative discharge coefficient values are relative to the value entered for "Discharge Coefficient (fully open)". Valve Characteristic Curves Valve characterisic cuves for standard types are based on published data (Fok, 1987). The curves have the functional form: 1 – Yk ... where needle valves have k = 2.0; circular gate valves, k = 1.35; and globe valves k = 1.0; or (1 – Y )k ... where for ball valves, k = 1.35; and butterfly valves, k = 1.85. More information can be found at the following paper: Fok, A.T.K., “A Contribution to the Analysis of Energy Losses in Transient Pipe Flow”, Ph.D. Thesis, University of Ottawa, 1987. Note: most valve manufacturers can provide the discharge coefficient(s) Note: When modeling a valve whose initial status is "inactive", ensure that you've entered a value for the "minor loss coefficient". When computing initial conditions, the "minor loss coefficient" is used to compute headloss through the fully open (inactive) valve. This headloss is important since it is used to define the relationship between head loss and discharge as the valve closes. Example Model In the latest version of HAMMER, this example model can be found in the "Samples" folder within the installation folder and is called "Valve_Closure_Example.wtg". For older versions that do not have this, you can download a version of it here: Click to Download Note : the above model is for example purposes only. It can be opened in version 08.11.00.30 and above and you can find additional information under File > Project Properties. Also, you must be signed in to Bentley Communities or the link will not work . Reference Advanced Water Distribution Modeling and Management - Walski, 2007 See Also Gradual closure not occurring when using valve operating rule Protective Equipment FAQ Modeling An Initially Partially Closed Valve Modeling Reference - Valve With Linear Area Change Using Modulating PRVs General HAMMER V8i FAQ
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Forum Post: RE: Flowmaster open channel analysis issue
Yes, every turbulent flow head loss equation is empirical and you don't have laminar flow in open channels..
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Forum Post: RE: Flowmaster open channel analysis issue
I guess Uniform flow is not the same as laminar ? Not a native speaker, but thats what I previously had assumed.
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Forum Post: RE: SewerGEMS in ArcMap - Disappearing Fields
Connor have you already upgraded your SewerGEMS? Did the Synchronze Drawing command help? I am not able to reproduce this issue, though I have not yet tried testing on a virtual machine with limited rights. I suspect the problem may be with your version, or permissions. I will plan to take a deeper look this weekend if I am able to.
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