Flow going backwards through a pump? Then the pump starts rotating in reverse? Where the heck is the check valve to stop the flow? These are all great questions (which I will answer later in this article). Theodore von Kármán and Robert Knapp were working on these questions in the early 1930's. Most engineering students encounter von Kármán in thei...

While thinking in terms of pressure is often intuitive for engineers, thinking in terms of head can be more challenging. You may be surprised by the number of cases and questions that come to the support team here at AFT about the basic definition of head, and how it relates to hydraulic modeling. Let's get back to the basics with how head is defin...

When I wrote AFT Impulse 1 back in 1996, I slipped in an undocumented feature to make it capable of modeling the first waterhammer project I did in industry. Since then, this feature had a secret (i.e., undocumented) way of being enabled. AFT Impulse 8 will be released any day, and we have finally made this feature accessible to all. In the User Op...

In June 2020, AFT's Reinaldo Pinto presented the webinar Calculating Transient Forces for Pipe Stress Analysis. The webinar focused on generating unbalanced forces due to surge in AFT Impulse and exporting them to CAESAR-II. During the webinar, 28 questions were asked. Below are the responses.  Download the presentation: www.aft.com/...

At the time of writing, AFT Impulse 8 is right around the corner. We are proud to boast of new capabilities to give you an even better user experience with transient analysis. AFT Impulse 8 showcases new features never seen before, and ones only hinted at with the releases of AFT Fathom 11 and AFT Arrow 8. Here, we have laid out the top 5 new featu...

Really? Another blog about features in AFT software? Yes, really. And there is a good reason for it. Because this new feature in AFT Impulse 8 will change your life. Well, it may not change your life, but it will forever change how you do your waterhammer analysis. I am talking about the new multi-scenario graphing and animation feature. This brand...

Any time a rapid transient occurs in a piping system, there is a chance for unexpected surge to impact the system. Though system shutdowns account for many surge events, pump startups can cause water hammer as well. For this blog I am going to cover the basics of setting up pump and valve transients for the startup case in AFT Impulse 7, as well as...