An OpenFlows HAMMER model can help identify where and how the pressure drops can occur and help design the needed control measures. Centrifugal pumps are great at pushing water through a pipe. They aren’t as proficient at sucking water through a pipe. As a pump pulls water into its impeller, it lowers the pressure.
There is no shortage of conferences serving the water industry. Each of them contributes something to our profession, and attending is usually worthwhile, if not life-changing. But which ones should you attend? You can’t attend all of them, or you wouldn’t get any work done. I’ll run through a few of the conferences I’ve attended, and I’ll give you my thoughts below.
Writers working with large numbers often feel compelled to display digits beyond a reasonable level. For example, they may want to report a pressure as 27,871 psf, when only the first two digits are meaningful. Two solutions to this are to use a more reasonable unit such as converting that value to 190 psi. The other option is to scientific notation and report 28 x 103 psf.
A key input to a water distribution system model is the demand assigned to locations in the system. For most of the history of modeling and most models today, these demands are based on a known volumetric flow rate. Some, however, would argue that all water leaves the system through some kind of pressurized orifice and demands should be modeled as pressure-dependent. Software today, like OpenFlows WaterGEMS, has the ability to model demands as volume-based or pressure-dependent.
Collection system models like OpenFlows SewerGEMS are a powerful tool in their toolbox to assess the problem and develop solutions. The requirement is to develop a method to produce hydrographs based on a simple and reproduceable approach using data that are readily available. The most successful methods can reproduce the total quantity of I&I, the time to peak and the duration of the recession limb of the hydrograph.
To maintain adequate self-cleaning velocity, you need smaller pipes, which means you need to pump. By varying the diameter in model runs, you can look at the effect of trading off velocity vs. head loss.
A key input to any model with pumps is some form of pump head curve showing flow vs. pump head. Given the curve, the model can tell the user the exact point on the pump curve at which the pump will operate.
One of the most common questions we get from our WaterGEMS/WaterCAD users is how to model the connection between a proposed land development and the water distribution system supplying it.
These days, I get involved in a lot of discussions about “digital twins”. One of the most common questions is, “What is a digital twin?” With so many people talking about this, you would think that by now there would be a clear definition. Several organizations have written definitions. I sit on an AWWA Committee whose mission is partly to come up with a definition. So far, we haven’t come up with the perfect definition, and we probably won’t.