tag:blogger.com,1999:blog-1675184707067447729.post5144994930540520126..comments2023-07-12T07:12:04.697-07:00Comments on The RAS Solution: Modeling Junctions for Unsteady Flow AnalysisChris G.http://www.blogger.com/profile/00354834185663924786noreply@blogger.comBlogger11125tag:blogger.com,1999:blog-1675184707067447729.post-56252446363137144542018-12-13T16:24:44.235-08:002018-12-13T16:24:44.235-08:00Yes, you should include this. You can add the cro...Yes, you should include this. You can add the cross section where you want to add this flow as an internal boundary condition location in your unsteady flow editor. Then add a lateral inflow hydrograph to it as the boundary condition. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-68006175051476154462018-10-24T09:52:12.196-07:002018-10-24T09:52:12.196-07:00Chris,
I have stream system about 400 km long, ru...Chris,<br /><br />I have stream system about 400 km long, running from a reservoir in the upstream to a lake in the downstream. The river flows at about 100 cms. Then a tributary (it actually flows greater, with daily mean discharge of 300 cms) joins the system in downstream, about 100 km from the downstream lake. <br /><br />When I run unsteady flow analysis, should I add this tributary flow as a lateral inflow as a boundary condition? How can I do that? For my first run, I forgot to add this tributary flow, but results at upper stream part of the river (about 100 km from the upstream reservoir) seems ok. <br /><br />Any advice?<br /><br />WestWesthttps://www.blogger.com/profile/14027840397254644387noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-44558327059293333452016-08-12T12:54:38.270-07:002016-08-12T12:54:38.270-07:00ineffective flow areas and possibly levees.ineffective flow areas and possibly levees.Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-55981245580544890852016-08-12T10:47:37.192-07:002016-08-12T10:47:37.192-07:00hello, in a river I have an inconsistency in the f...hello, in a river I have an inconsistency in the flow, the river is flooded but there are sections<br />intermediate where water fits perfectly, the only way to resolve this error is varying mannings in the sections that are not flooded, is there any other way?Marisolhttps://www.blogger.com/profile/16850536623614870278noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-16172853864435180322016-05-01T19:46:50.298-07:002016-05-01T19:46:50.298-07:00thank you
i asked you one moment ago
but you excel...thank you<br />i asked you one moment ago<br />but you excellent statement " The initial flow just downstream of the junction should be the sum of the initial flows of the 2 converging reaches." solved my problem<br />Dr HossamAnonymoushttps://www.blogger.com/profile/07715510048646401060noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-72958630954474391102015-03-06T08:45:52.309-08:002015-03-06T08:45:52.309-08:00The initial flow just downstream of the junction s...The initial flow just downstream of the junction should be the sum of the initial flows of the 2 converging reaches. Junctions are notoriously hard in unsteady flow, especially in steep reaches with low stages. Have you read these posts also?<br />http://hecrasmodel.blogspot.com/2008/12/unsteady-flow-and-junctions.html<br />http://hecrasmodel.blogspot.com/2009/02/how-to-best-model-junction.html<br />http://hecrasmodel.blogspot.com/2009/02/severe-energy-jump-at-junctions-for.html<br /><br />If this doesn't help, please send me your model and I'll see what I can do.<br />Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-35895500372720153582015-03-06T08:33:36.994-08:002015-03-06T08:33:36.994-08:00Maybe 've missed it, any suggestion for settin...Maybe 've missed it, any suggestion for setting initial flow in the first section after the junction?<br />I've run two separate models without a problem, but when i join the models with a juction the evil red line become the master of my pc. it crashes in the very first steps, so i assume can be the initial condition... but i'm not sure... Help please, this thing is driving me crazy (sorry for my bad english :))panicelluhttps://www.blogger.com/profile/10270520095734914105noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-7924178662221542992013-06-28T08:44:55.003-07:002013-06-28T08:44:55.003-07:00That sounds like a good way to model this, as long...That sounds like a good way to model this, as long as the dam breach effects have diminished by the time the floodwave reaches the junction.Chris G.https://www.blogger.com/profile/00354834185663924786noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-83127295092324400212013-05-24T09:31:20.677-07:002013-05-24T09:31:20.677-07:00I have a very small stream coming into a larger cr...I have a very small stream coming into a larger creek and I'm having trouble getting my unsteady model to compute correctly at the junction. For the event I'm running (the 1%, 24-hr storm) the larger creek backs up into the small stream about a thousand feet. The model is for a dam breach on the smaller stream, and the no breach and breach profiles will converge well before the junction because of the backwater effects of the larger creek. Would it be incorrect to model the small stream and larger creek separately, then use the stage profile from the larger creek (at the location of the junction) as the downstream boundary for the small stream? It seems like this would account for the backwater effect, but maybe I'm missing something? Lisahttps://www.blogger.com/profile/00175338510275425569noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-7777941256101214782013-05-06T22:54:40.784-07:002013-05-06T22:54:40.784-07:00It could be any number of things. Start with the ...It could be any number of things. Start with the errors that show up on the computation messages. Then see what is happening in the profile plot. Look for instabilities in your profile plot as you animate. Then look further at any cross sections that may reveal clues to sources of instabilities. Quite frankly, you are trying to stabilize an unsteady HEC-RAS model. It takes practice. Read up in the manual about what to do for an unstable model. Also, search this blog site some more. Sorry I can't be of more help, but your description is very general and it's impossible to tell you what is causing it to crash via a message board. Chris G.https://www.blogger.com/profile/00354834185663924786noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-69764688189080454422013-05-06T21:09:18.772-07:002013-05-06T21:09:18.772-07:00Hi, what should i do if the Hec-Ras cannot run the...Hi, what should i do if the Hec-Ras cannot run the simulation, the red color comes out when the simulation is running? i am working with junction for unsteady flow analysis, Energy Balance Method and Force Equal WS surface. There are 2 combining junctions and 1 split junction. One of the upstream reach is steeper than others. The simulation succeeded in HEC-RAS version 4.0. Could you please give me some advises? Thank you.Anonymoushttps://www.blogger.com/profile/11207506909002168212noreply@blogger.com