Does anyone know if there are any tricks to getting SRH's pressure flow BC to run stable with overtopping? I am working with very large (>100,000 cfs) flows and have already tried varying the grid cell size in the vicinity of the bridge from 5'x5' to 20'x20'. I don't get any errors but when I plot weir flow it oscillates over a magnitude of a few thousand cfs. I am using holes in the mesh to represent piers.
I have gotten the model to run stable for a few simulations, but whenever I make some changes to the mesh it's a trial and error process of trying to get the overtopping stable again. Are there any tricks or bugs I should know about?