I’m trying to use minor losses in HEC-RAS steady flow analysis, but it doesn’t seem to work (no change in WS). I entered K values (ranging from 0 to 1) in the appropriate table in the Geometry editor.
k values are not meant for minor losses. They are an alternative to n values. The advantage of using a k value is that RAS then computes an n value that is a function of (not only k but also) depth. Please read chapter 3 of the hydraulic reference manual for more information.
Frankly, I don’t hear of people using k values that much in RAS, so I wouldn’t be suprised if there are some bugs in the software when trying to use them.
The K I’m referring to is the coefficient in the minor losses menu, under table menu in the geometry editor. This coefficient should be multiplied for the kinetic height of the section and included in the energy equation, to model minor losses caused by bends or other localized headlosses.
My problem is that is not working at all, since Water level stay the same whatever K number I input.
Ah…got it. Sorry about the confusion. I just tried it on a flume example I have (I applied 0.5 loss coefficient to the entire reach), and it definately works. Perhaps your velocity head is very small, so the minor losses are too small to detect in the output?
I even tried changing from SI to US units (just to check if it was a bug) but nothing. It doesn’t change anything in profile, and velocity are about 1.5 m/s, so with a unitary coefficient I should see a 0.11 m headloss.
I’ll experiment more and write here if I have news.
I have the same issue. k values when input from the geometry editor are not recognized. when input using the flow editor (options->set changes in WS and EG..->K Loss) they seem to be recognized. seems to be a bug in RAS