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cameronParticipant
could you do a gradual open and gradual close of the pumps? maybe only turn on a couple at 1.0m and a couple more at 1.1m and so forth? Not sure how big the pumps are, but 8 starting or stopping at the same time might be causing a shock to the models.
cameronParticipantThose are common error messages in Unsteady HEC-RAS which just states it couldn’t converge to a solution within the iterations so it picked the best value and moved on. Depending on what type of study you are doing, the error amount may or may not matter. For instance, with dam breach studies I try to keep the error value below 1.0 and for other studies below 0.5 or less depending on how complex the model is.
In your case the two largest errors occur right at the beginning of the simulation and so the error would have something to do with your initial conditions. Not sure the purpose of the study, but I would probably not worry about the error as it is not that large and goes away eventually.
cameronParticipantreach lengths need to be positive. Reach lengths are entered in the cross-section editor. If you developed your model using GeoRAS, you might have digitized your flowpath lines in the wrong direction.
cameronParticipantCourant Criteria. Basically you don’t want your max velocity to be greater than your time step.
July 13, 2017 at 4:52 am in reply to: Create Terrain – Error in stats generation, values came back NaN #10729cameronParticipantwhy are you converting it to a float file? HEC-RAS can read geotif files and is what it converts it to when all is said and done.
cameronParticipantYou could do Mannng’s or Minor Losses (in the table pull down menu). Knowing the correct value to use is the tricky part as you would want to calibrate it to something if possible.
cameronParticipantThe ESRI prj file is different than the HEC-RAS prj file. You need to determine which projection you are working in and create a prj file that represents that either in GIS or download from a website.
http://desktop.arcgis.com/en/arcmap/10.3/guide-books/map-projections/what-are-map-projections.htm
cameronParticipantWhat is your inflow and downstream boundary? Based on your cross-section plot, you must have a ton of water coming in or the downstream boundary is controlling the wse. Do the reach lengths between the cross-sections make sense? Did you think about adding levees to force the water to stay where it should go?
July 3, 2017 at 6:02 pm in reply to: Breakline and Cell Spacign Techniques at Roads/Linear Strutures in 2D #10686cameronParticipantAs I look more closely at the mapping, I agree with Lonnie on what is happening. So either you add more grid cells along the top of road or plot the Depth Max Extents which shows a cell fully wet if any portion of it gets wet.
cameronParticipantAre you using the latest version of HEC-RAS?
cameronParticipantThese tell you if the results are converging or diverging.
cameronParticipantDo you have a storage area curve for the lake? You could break your model up into multiple 2D areas and have a storage area for the lake or modify the terrain near the lake.
cameronParticipantIf you have lateral structures between each reach then the flow will be able to go from one reach to the next.
cameronParticipantWhat do the results look like in the cross-section? Do they extend to the edge of the cross-sections?
cameronParticipantI would either switch to a bridge or add additional losses to the cross-sections where there is submergence happening.
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