With the new HEC-RAS release im sure everyone has been attempting to decrease their model run times with this new feature. However, if you are modeling large areas with precipitation, be weary of this. The courant numbers discussed in the supplemental manual dont fit well with flat/mild sloping terrains. Courant numbers could be extremely high by following the criteria of velocity(dt/dx) . For models in the past where i have had stability and continuity balance at a certain dt, the criteria for optimizing this model will shift the dt even lower.
For precipitation models, in areas where velocities will never be high, the Residence Time option should be utilized instead.
What i am unsure of is: how does the criteria for residence time coincide with the options given for input?
Number of steps below....etc. It was my understanding that residence time is independent of these inputs.
Thanks cameron, this is my issue though. The Min and Max values are essentially picked from the air.
I have models in the range of 1.6 million cells, and the selection of these variables, like you said, can prove to run a model even slower than previously. The guidance for the selection of these variables was poorly outlined imo. Any help on this topic is appreciated.