We really enjoy developing features and working with our many users of our transient flow (waterhammer) software. Take a look at the new animated profile display coming with Pipe2010: Surge. This tool will make your presentations very impressive. Our success and dedication to providing the best possible transient flow modeling tool out there does attract attention from our competitors. One of the most disturbing claims we have to address from time to time is the claim that the ‘wave method” that we employ (sometimes referred to as the Wave Characterstic Method (WCM) is somehow less accurate than the convention and usually prepexing Method of Characteristics (MOC) approach. Folks, there is one correct solution to a transient flow problem and that is what we provide as, hopefully, our competitors do also. Take a look at below at the calculation of the pressure at a junction within a pipe system following a valve closure at some other location. This is a typical rather irregular pressure history that we get when we do transient analysis. The point here is that you are looking at two solutions superimposed on one another. One was done using the MOC and the second using our wave method (WCM) which is employed in Pipe2010: Surge. The solutions are identical as they should be. We have made the same type of comparison with the same results for many situations. This particular example first appeared in a classical reference book by Streeter and Wylie many years ago (1967). What is different about the two solutions is that the MOC takes many, many more calculations to obtain the solution. This makes the use of the MOC impractical for large municipal water systems while the WCM can easily and quickly handle large networks.
The wave method was developed nearly 50 years ago (for NASA) and has been used extensively over the past 25 years for all types of liquid transient flow calculations. Don’t let anyone tell you that the MOC provides a more accurate solution – just ain’t so!
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