Forum Replies Created
-
AuthorPosts
-
cameronParticipant
You can set the extents of the window by right in the window and selecting set schematic plot extents.
cameronParticipantYou can’t import a 2dm file into HEC-RAS 5.0 that I am aware of. Most 2dm files are triangular meshes and HEC-RAS does something different when meshing. Also one of the advantages of HEC-RAS 5.0 is you don’t need as small as elements as other 2D models.
cameronParticipantI never received it.
cameronParticipantThe junction length is the length from the upstream cross-section to the downstream cross-section. Usually it is the same length as the reach length for the main river. The tributary length is usually measured from the last cross-section of the tributary to junction to downstream cross-section on the main river.
cameronParticipantWith multiple openings, the split needs to be at a stagnation point. You can have the model calculate it for you if you slightly overlap the stationing of each opening type.
cameronParticipantYou could use multiple openings for the bridge and break it up into conveyance, culvert, and then conveyance sections or maybe a split reach.
I should point out that how you currently have it modeled will cause all flow going over the road to end up in the downstream channel which does not depict the actual flooding. It would appear that the flow would continue down the road by the buildings. If you care about the depths of water near the buildings, I would do a split reach or even a 2D model.
July 21, 2015 at 7:29 pm in reply to: Problem with displaying Deck/Roadway Data in longitudinal profile #9439cameronParticipantIt is just a graphical thing, you are doing nothing wrong.
cameronParticipantYou can send it to me through we transfer and I will take a look.
cameronParticipantHave you thought of increasing the size of the test? There is UK Benchmark test I have tested with RAS 2D, where they have a small flume and the the small flume multiplied by 20. The small flume from my tests does not give very good answers compared to other models, but the flume multiplied by 20 does give comparable results to multiple other 2D models.
If you would like you could send it to me by “we transfer” and I can take a look.
cameronParticipantWhat is your time step set at now? my guess is you need to be at 0.1 or smaller.
cameronParticipantFirst I might say that HEC-RAS 2D is probably not designed to handle mesh elements of 1mm or 1cm in size as this would be more of a CFD size.
As for errors, when you create the mesh did you adjust the tolerance values in the mesh editor to be smaller than the default?
The width error could be referring to the the weir stationing of the dam and not the actual line you drew.
If you need to convert it to US units, under the “Option” pull down menu there is a convert units tool. You could use this to convert and then test in US units.
cameronParticipantQuasi steady is different than full unsteady with sediment transport and your time step will be different. The CFL criterion is generally for unsteady, unsteady sediment, and 2D. I would think hourly would work with Quasi steady.
As for cores, the only place I know of specifying the number is in the Unsteady calculation options window.
cameronParticipantIt appears you are running the model in unsteady with sediment transport instead of quasi-steady.
5 meters is pretty close for cross-sections and I would assume you would need a smaller time step. I would recommend getting the model working with good results without sediment transport. Once you are happy with the results, turn sediment transport back on.
Note that the program is keeping track of sediment transport, it will only adjust the cross-sections based on what you specify and what you pick is dependent on your time step.
For the CFL criteria, I would use the same one you would without sediment transport.
Once the final version of HEC 5.0 is released there will be a brand new manual just for sediment transport which will have a lot of good information on all of the questions you have.
cameronParticipantIf you do need to get the time step smaller than 0.1 seconds, you can turn on time slices in the 2D options window. Whatever value you specify will be used to divide the 0.1 seconds so your time step will be smaller.
cameronParticipantI am not aware of a way to turn of reaches and only test specific reaches. The two options you have would be to do a separate geometry for each reach or put dummy flows in the reaches you don’t care about.
-
AuthorPosts