tag:blogger.com,1999:blog-1675184707067447729.post3815398903456296564..comments2023-07-12T07:12:04.697-07:00Comments on The RAS Solution: Transect for Extracting Flow in a 2D AreaChris G.http://www.blogger.com/profile/00354834185663924786noreply@blogger.comBlogger43125tag:blogger.com,1999:blog-1675184707067447729.post-19175450064409677732019-03-12T20:11:55.677-07:002019-03-12T20:11:55.677-07:00I find some improvement in version 5.0.6. Now you...I find some improvement in version 5.0.6. Now you can see a new button called " clip weir profile to 2D cell…" in Lateral Structure Editor and SA/2D Editor. It uses minimum elevation of 2D cell connected to weir and elevates the line some height specified by you as weir profile. I think this could eliminate connected error due to some location of weir profile lower than cell minimum elevation and reduce our efforts.lilith894https://www.blogger.com/profile/11960333567687057989noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-64534075180954186492018-12-19T21:32:43.368-08:002018-12-19T21:32:43.368-08:00No, unfortunately there’s not a lot the hecrascont...No, unfortunately there’s not a lot the hecrascontroller can do with 2D. But you might explore writing code to read from the hdf file. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-3490339450330987282018-12-19T08:19:17.393-08:002018-12-19T08:19:17.393-08:00Hi Chris. Great post as always- thanks very much. ...Hi Chris. Great post as always- thanks very much. Is there a way to extract the flow at profile lines (I'm using Version 5.0.5) through the HEC RAS controller? The "OutputDSS_GetStageFlow" function does not seem suitable in a purely 2D model? Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-52149998039542946572018-11-08T14:01:51.521-08:002018-11-08T14:01:51.521-08:00Whoops ... I just noticed the update note at the t...Whoops ... I just noticed the update note at the top of this blog ie. "*Update: Version 5.0.2 now does flow transects in RAS Mapper with profile lines. No longer necessary to use a 2D Area Connection to do this". I am using ver 5.0.5 - the "Profile Lines" tab resides in the lower left-hand side of the "RAS Mapper" window. Excellent!Mario Brischettohttps://www.blogger.com/profile/17120208741208765826noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-88914294228974393912018-11-08T13:49:01.057-08:002018-11-08T13:49:01.057-08:00***The blog is so helpful thank you for making the...<br />***The blog is so helpful thank you for making the effort and inspiring others to do the same*** Hey Chris C and Chris G, it seems the problem still exists for HEC-RAS ver 5.0.5. The method I have adopted is to: 1. copy the name of the SA station and the list of erroneous stations from the "Computation Messages" window, then paste to MS-Excel for ease of reference; 2. copy the weir profile for the given SA-2D connection,then paste to MS-Excel; 3. adjust the weir profile ONLY at stations immediately adjacent to the listed erroneous stations ... it seems the erroneous station occurs between weir stations at the intersection the weir profile and mesh surface ... adjacent stations adjustment = error amount plus 0.001. 4. paste the weir profile back into HEC-RAS. ***Mario Brischettohttps://www.blogger.com/profile/17120208741208765826noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-54071644239929817252018-11-07T18:43:32.367-08:002018-11-07T18:43:32.367-08:00Thank you for taking the time to share your findin...Thank you for taking the time to share your findings, which often saves "trying to find a needle in a haystack" and inspired me to share. I know this is an old thread, but it seems this issue still exists in the current version of HEC-RAS (I am using v5.0.5 for 2D unsteady flow analysis). I have found that the discrepancy can require more than 0.007 (perhaps due to the steepness of terrain versus the cell mesh spacing), however I am adjusting individual points in the weir profile which minimises the impact on the model. (Method = copy terrain profile, paste into weir profile, run unsteady flow analysis with a long time step for quick turn-around. The erroneous points are listed in the run log. Typically there are only a few erroneous points each time so I simply paste the relevant terrain profile into MS-Excel, and then increase by the error amount plus 0.001 the level of the user-inputted weir station on either side of the erroneous station, and then paste as the weir profile and rerun to unsteady flow analysis which fixes the problem. The erroneous station seems to be the point where weir profile crosses the mesh surface and therefore fall between the manual stations).Mario Brischettonoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-37015237643596691392018-05-06T10:24:35.795-07:002018-05-06T10:24:35.795-07:00I feel your pain ;-)I feel your pain ;-)Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-10459921662351866512018-02-19T21:03:39.409-08:002018-02-19T21:03:39.409-08:00Cameron - try restarting the RasMapper. Sometimes ...Cameron - try restarting the RasMapper. Sometimes it runs out of memory when reading the hdf files. Alexhttps://www.blogger.com/profile/09498564757387404239noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-78453237592064936222018-02-15T14:08:56.543-08:002018-02-15T14:08:56.543-08:00Hi Chris,
I ran the simulations using the 2D Area...Hi Chris,<br /><br />I ran the simulations using the 2D Area connections. A time consuming process but successful. I did draw some profile lines in the RAS Mapper that followed the same alignment as the 2D area connections in the geometry and was able to compute flow and volume accumulation (yay)!<br /><br />I did try extending the profile lines beyond where I'd drawn the 2D area connections (as they hadn't captured all the flow) and I got the error I have seen many times before when plotting time series of flow / volume. The error states:<br /><br />"Unhandled exception has occurred in a component in your application. If you click Continue, the application will ignore this error and attempt to continue.<br /><br />Exception of type 'System.OutOfMemoryException' was thrown"<br /><br />I believe now that this error shows up when trying to do these time series calcs where the cells do not align with the profile lines. What I'll do in future simulations is not draw 2D area connections but breaklines (to align the cells) and convert breaklines to profile lines in RAS Mapper. It's not the size of the simulation or the profile line thats the issue (I tried it with the breakline that represents the centreline of my river and it eventually calculated the flow across it) but if you're trying to calculate along a profile line that does not align with the cell facesAnonymoushttps://www.blogger.com/profile/17525908291113651376noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-9341087518977653262018-02-14T10:13:18.482-08:002018-02-14T10:13:18.482-08:00Nice!Nice!Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-11009406248916608472018-02-13T19:08:00.376-08:002018-02-13T19:08:00.376-08:00Thanks very much Chris. Yep that was the problem. ...Thanks very much Chris. Yep that was the problem. Changed grid space to 2m and time step to 0.5secs and all looks pretty good.Anonymoushttps://www.blogger.com/profile/03658627364527119807noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-22353293468188435772018-02-13T08:22:57.017-08:002018-02-13T08:22:57.017-08:00Hi Stuart. Melbourne was awesome! Nice to hear f...Hi Stuart. Melbourne was awesome! Nice to hear from you. From what you've described, I bet the model is unstable in the 2D mesh. While it's very easy to spot instabilities in 1D reaches using the profile plot, they are not so obvious in 2D areas, unless you check the numbers. Though subtle, there are some visual hints that can reveal an instability. Look for a "pulsing" effect while animating your depth map. Also, look for pixelation in the depth map, particularly at the front end of a flood wave. But of course, the numbers are the real test, as you know. My suggestion would be to try getting your Courant numbers down below 3, but as close to 1 as is practical. see if that helps resolve instability issues. Good luck!Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-83272154789597899502018-02-13T03:01:25.506-08:002018-02-13T03:01:25.506-08:00Hi Chris,
I did the Hec-Ras 2D modelling course ba...Hi Chris,<br />I did the Hec-Ras 2D modelling course back in 2016 when you were in Melbourne and have been really enjoying using it since. I am doing a flowpath assessment in an urban environment and after running my model I was concerned that the flow depths / extent were too large, so I setup cross section breaklines as described in your post mentioned above from 2015. Based on the results of this run, the peak flows are significantly higher than the inflow hydrographs that I have entered. I have many different inflow hydrographs due to the length of the catchment and various incoming points of flow, however even if I were to combine all of these at the same time to peak (unrealistic) the flows shown on the transect are way too high (sometimes by many magnitudes). Can you think of any reason why this would be occurring ?<br />Thank you in advanceAnonymoushttps://www.blogger.com/profile/03658627364527119807noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-3525659767409915962018-02-11T10:08:49.542-08:002018-02-11T10:08:49.542-08:00Interesting. I haven’t had issues using profile li...Interesting. I haven’t had issues using profile lines on larger projects.aybe they’ll have this tightened up better for the next version. Cheers-<br />ChrisChris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-37351243631588325722018-02-11T03:26:25.013-08:002018-02-11T03:26:25.013-08:00Hi Chris, I did try using a nominal weir that was ...Hi Chris, I did try using a nominal weir that was 30m above the channel invert, but the weir actually has an impact on the flow by retaining it. The 2D equation option only works when the weir is being overtopped unfortunately. So you need to copy the terrain profile, filter it down to 500 points or less, and add 0.01 so the weir is above the headwater (HW) and tailwater (TW) cells. I wish if the 2D option was selected that you wouldn't need to input all this weir data, as it can give you quite a lot of errors.<br /><br />It's quite a time consuming process but unfortunately I haven't managed to get the profile lines to compute flows or volume accumulation on the larger projects, so the SA/2D area connections are the best way to compare how the flow attenuates as it moves downstream.Anonymoushttps://www.blogger.com/profile/17525908291113651376noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-51598871906243035602018-02-11T02:38:14.297-08:002018-02-11T02:38:14.297-08:00Hey Chris, I've experimented with putting in n...Hey Chris, I've experimented with putting in nominal weirs that sit above the terrain and they do have an effect on the flow. The flow backs up behind the weir, the 2D Eqn domain is only used for the water that overflows the weir crest. So you do need to profile the terrain, filter it down to 500 points and normally add 10mm so the cell faces are lower than the weir elevation on the headwater (HW) and tailwater (TW) sides.<br /><br />I'm having to use the SA/2D area connection method to measure flows throughout the model, as the profile lines cannot compute the flow for large models. It's a bit painful to set up if you want many flow transectsAnonymoushttps://www.blogger.com/profile/17525908291113651376noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-76149476833356603282018-02-09T12:29:47.522-08:002018-02-09T12:29:47.522-08:00The 2D area can be sampled 2 ways. The first way (...The 2D area can be sampled 2 ways. The first way (recomended) is to generate breaklines and in RASMapper transform them into "Profiles Lines". Once these are set as "profile lines", you can sample hydrographs. You would have to load a new result layer for a given "Unsteady Profile" other than maximum/minimum. You can select any, and you can modify the time in the time bar. Once you have this layer loaded and displayed, all you have to do is to right click on the 'profile line" to get a stage hydrograph, a flow hydrograph, velocity, depth...<br />A second method (not recomended) would be to pre-set SA/2D connections in the locations that you would like to sample hydrographs. This can be effective, but it can conflict with the configuration of other structures in the 2D Area.Alexhttps://www.blogger.com/profile/09498564757387404239noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-73672080959606016072018-02-09T12:07:19.745-08:002018-02-09T12:07:19.745-08:00That would be the values associated with the upstr...That would be the values associated with the upstream (HW) and downstream (TW) flow depths. These values would depend upon how you draw your SA/2D Connection.Alexhttps://www.blogger.com/profile/09498564757387404239noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-1791159979113986312018-02-03T21:24:01.276-08:002018-02-03T21:24:01.276-08:00I have the same issue jmaynard. Did you manage to ...I have the same issue jmaynard. Did you manage to solve this?Anonymoushttps://www.blogger.com/profile/11223010146317127901noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-26502781795855713822018-02-03T21:22:33.947-08:002018-02-03T21:22:33.947-08:00I have the same issue as you jmaynard. Did you man...I have the same issue as you jmaynard. Did you manage to solve this problem?Anonymoushttps://www.blogger.com/profile/11223010146317127901noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-37887213775436997552018-01-16T13:40:50.017-08:002018-01-16T13:40:50.017-08:00You can also use DSSVue to retrieve TW HW stages a...You can also use DSSVue to retrieve TW HW stages and peak discharges. This is a great idea, thanks for sharing Chris. Alexhttps://www.blogger.com/profile/09498564757387404239noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-44885104278052966042017-12-07T14:52:23.370-08:002017-12-07T14:52:23.370-08:00Bill, I'm not surprised by that. My guess is ...Bill, I'm not surprised by that. My guess is that RAS extracts flow through cell faces. If those faces don't line up on the profile line you draw, then you get the "jagged line" output. I assume you could still forego the old method of using a SA/2D area connection by just drawing a breakline where you have your profile line drawn. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-48705554678875872072017-12-07T14:41:24.606-08:002017-12-07T14:41:24.606-08:00Chris, I believe that HEC-RAS 5.0.3 measures flow ...Chris, I believe that HEC-RAS 5.0.3 measures flow along the jagged edges of the cells along the profile line drawn in a 2D flow area and not directly along the profile line itself. I think that there still is need for 2D flow area breaklines (and storage area connection) as previously-described if you want flow directly along a profile line. I can send a screenshot of how HEC-RAS shows both the profile line and the jagged line along cell faces after you right-click on the profile line and select "Time Series" --> "Flow". A funny thing is that HEC-RAS shows only the profile line when right-clicking and getting a plot of WSE.Anonymoushttps://www.blogger.com/profile/01633631365428321116noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-77247648447148957302017-12-01T10:17:00.015-08:002017-12-01T10:17:00.015-08:00In the table on the right side of Stage and Flow H...In the table on the right side of Stage and Flow Hydrographs are reported HW and TW max values. To which cell are they related?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-3886332233695167232017-01-27T18:49:39.565-08:002017-01-27T18:49:39.565-08:00Now we're up to 5.0.3. There's a link to i...Now we're up to 5.0.3. There's a link to it on the side bar on The RAS Solution. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.com