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NickV

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  1. Thanks for your response. I tried changing the timestep, changing the size of my mesh elements, etc. Only after I removed my pressure structure downstream did I get a smooth model run. I knew the problem was there. After a closer check, I had assigned the up- and down-stream low-chord elevations to the correct elevations (1500' or so) and I set the crest elevation using an elevation from another project (1300' or so). The model was trying to run water under 1500' but over 1300'. It was an operator error, but is there anyway to get a warning of this type of error in future releases? Something that will alert a user that these two elevations do not make sense? I know for future reference to check this area first but a warning would be nice. Thanks
  2. I originally had the weir BC snapped to the top edges of the wall, I moved the weir BC to snap to the bottom edges of the wall. This seems to have fixed the problems at the weir and upstream from it. I am still having problems downstream of the weir and around the box culvert further downstream.
  3. Photos wouldn't post in original. This is the weir structure.
  4. All, I am setting up an SMS SRH-2D model that has a dam/weir structure in the main channel. I have assigned three weir BC's as there is three segments with different heights. The existing wall is about 20 inches wide. The *OUT.dat file says SRH-2D successfully executed, but the results vary greatly across each time step. I get successful runs at both high and low flow conditions with the same varying results. I thought I had the mesh and boundary conditions for the weir entered correctly, but I cannot figure out what is going on as this is my first attempt at using a weir structure. Does anyone know of a checklist of sorts that I can run through to confirm I set it up correctly? Any advice or tips? Thanks in advance!
  5. I have made new meshes for each option and it appears the results are more consistent with what would be expected with the various culvert box sizes. For the culverts, would it be better to represent my vertical piers with obstructions in the BC or to add the small element along the sides? Thanks again for all the tips and advice in this thread.
  6. I have successfully ran the model several times with various crossing configurations. I have a few reservations about the accuracy of the results. First the RCP culvert options. I made the changes we discussed and the model successfully runs. I created two simulations using the same mesh, material, and monitor coverages. I duplicated the BC I used for the four 48" RCP culverts and modified the BC to use five 48" RCP culverts. The results show an increase in water elevation upstream, even with the extra culvert. The only thing I changed was the number of culverts in the HY-8 window. Is there more to this than what I have done? These results do not match what I believe would make sense. More pipes = more flow which should lower the upstream water elevation or at the very least not cause an increase. Also, I know this option will overtop at the 100 year flow. Does it matter that the crossing is over topped, but due to the culvert assignment, the elements over the culvert display as dry? Will this impact my results in anyway? (see the screenshot for clarity) For the pressure culvert (box culverts) options. I believe I know this answer, based on my results, but will I need to create a new mesh and modify it to fit the dimensions of each culvert? I.E. to model a 3 barrel at 10'Wx9'H and at 10'Wx10'H, I created one mesh and two BC coverages and modified the ceiling elevations accordingly (I set the crest for both at an elevation that would not overtop). These two models created the same water elevations upstream. Which isn't a stretch with just one foot higher ceiling. To test my theory, I used the same mesh and duplicated the BC of one and changed the length across the weir from 30' (3x10'W barrels) to 48' (3x16'W barrels) to model a 3 barrel 16'Wx9'H culvert. The results yielded no change in the upstream water surface elevation. So before I made a new mesh for every option of width, I wanted to confirm that I will have to do this and adjust the location of my vertical walls and locations of the piers to accurately represent the various widths of box culverts to model.
  7. Thanks for all the advice and help. Always learning with the software. I modified the slopes and the model is running now. I thought I had a good grip on Pressure BC models, but I got a curve ball with these RCP culverts. Thanks again for all the help. I will apply all the techniques and I will get back to you if there is still issues. It appears to be running the full simulation now.
  8. Yes, the vertical walls are seeming to make the model crash quicker. So even though the proposed crossing will have vertical walls in the form of retaining wall blocks, the model does not need to represent that? Is this taken care of in the HY-8 settings when assigning culvert attributes? Using the 2D culvert with pressure flow BC would more accurately represent a Box Culvert or a span bridge, correct? I am using this mesh to model my pressure structures for a 3 barrel box culvert and a span bridge (the holes in the mesh are only for the multi-barrel box culvert). For doubling the nodes you mean instead of having 6 elements across the creek at this point, I should use 12 like in the pressure images below? I only added more elements to this mesh so I could delete the elements for the 8-inch piers of the box culvert.
  9. I've attached a plan view and a view of the downstream side of the berm. This is before deleting elements to help the vertical wall issue. Hopefully this helps.
  10. The culvert option will over top at the 100-yr flow. The idea would be for it not to over top until the 25-year storm event but let it act as a weir during a higher event. I believe ultimately the culverts will not work but I need to show the client why it will not work. Does the culvert BC need to snap (Shift-Q) to the bottom of the berm or the top? Currently it is to the bottom. I will try deleting the elements along the face of the berm and see if that works for the 10-year flow. Any suggestions of screen shots that would help with this? I can provide screen shots but I am unsure of what might actually be of benefit to show. Thanks for the response.
  11. I am attempting to model a new driveway across a creek to determine the structure required to have a "no-rise" impact on the base flood elevation of the creek. In doing so, I am trying multiple options. I have successfully completed an existing "no-bridge" model and multiple box culvert and bridge options, I am having trouble with the models with HY-8 multi-barrel RCP culvert options. I copied and modified the existing mesh to create a berm to the dimensions of the driveway across the creek, added hy-8 culvert BC elements and ran the model. The model will say 100% complete, but will only complete about 1 hour of a 2 hour simulation. I have increased and decreased the time step to attempt to resolve this issue. In some cases it helps, others it doesn't. In either case, the results are very sporadic, changing with every time step. Is it normal to see such varying depths and velocities throughout the entire simulation when modeling culverts? Is there anything I can check that I might have over looked that might cause these results? I am using SMS 13.0.3. I have patch elements for both my channel and proposed driveway surface. Equilateral elements between the BC lines. I do have a material assigned to the roadway surface between the BC lines, I read in the newer versions it was not necessary to leave this area unassigned anymore for culverts. I do have near vertical elements on each side of the berm, would this area need to be deleted to represent a vertical wall? I have the inverts of my culverts 0.01 feet above the stream bottom as they will be placed in the creek at existing elevation and grade. I do not know what else to try as I am not getting any errors and the model will run but the results are not reliable. I would appreciate any help or advice. Thanks!
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