tag:blogger.com,1999:blog-1675184707067447729.post7509672730737339145..comments2023-07-12T07:12:04.697-07:00Comments on The RAS Solution: Unsteady flow and JunctionsChris G.http://www.blogger.com/profile/00354834185663924786noreply@blogger.comBlogger10125tag:blogger.com,1999:blog-1675184707067447729.post-3717926982195415072020-02-19T13:34:17.716-08:002020-02-19T13:34:17.716-08:00Hi Chris,
Thank You for the posts. I have generat...Hi Chris,<br /><br />Thank You for the posts. I have generated 100 year flood plain in HEC RAS and want to export this floodplain boundary lines as shape file into Civil 3D. Is it possible? What's up with .db file?<br />Thank You.<br />ShankarSGhttps://www.blogger.com/profile/16264510920295645728noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-58787442752649126502017-09-05T11:08:24.455-07:002017-09-05T11:08:24.455-07:00Yes. Try using an inline structure for one weir a...Yes. Try using an inline structure for one weir and a lateral structure for the other. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-47518880181781835722017-09-04T04:35:43.674-07:002017-09-04T04:35:43.674-07:00I plan to put two weirs ( of different widths) in ...I plan to put two weirs ( of different widths) in the same chamber to enable two different flow rates from a common inlet.<br />I need flows to split into 41 cum/hr and 200 cum/hr. The head over weir need to be the same.<br />Is it possible ?<br />Sandeep Pandharkarhttps://www.blogger.com/profile/15005710985947753682noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-14959511076419179122017-02-22T13:35:53.024-08:002017-02-22T13:35:53.024-08:00I agree, but that's just the way it is in RAS....I agree, but that's just the way it is in RAS. Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-32183239266290939812017-02-22T08:43:30.960-08:002017-02-22T08:43:30.960-08:00Hi Chris, I have one basic question about junction...Hi Chris, I have one basic question about junction, but it's bothering me why do we need to give flow data on every reach while modeling with a junction? For bifurcation, I guess may be it's needed as it hard to calculate what will be the flow in two streams. But, for confluence, why can't model sum up the upstream rivers flow and uses those as a total flow for next reach. Is it same with other 1D models as well or is it only in HEC-RAS? Any feedback would be appreciated. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-42888899843084261352011-04-29T08:57:33.031-07:002011-04-29T08:57:33.031-07:00Update: Version 4.1 does have a new feature that ...Update: Version 4.1 does have a new feature that computes energy loss over a junction in unsteady flow. A blog post on this will be coming soonChris G.https://www.blogger.com/profile/00354834185663924786noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-70025759206936850132009-07-10T15:16:46.331-07:002009-07-10T15:16:46.331-07:00For a steady flow model, the energy loss over the ...For a steady flow model, the energy loss over the junction would be underestimated in the reach where the junction length was not properly defined. In the current version of HEC-RAS, unsteady flow modeling simply copies the water surface elevation of the downstream cross section (d/s of the junction) to the one upstream of the junction. I was wrong when I said in my previous post that it is the same. In practice it should be set up the same way for steady or unsteady, but computationally, it is handled differently. For unsteady flow, the junction length would not be used at all and it would make no difference in the results. However, graphically it would look incorrect on plots and the geometry schematic. In the next version of RAS (4.0.1, soon to come out), unsteady flow will be able to compute energy loss over the junction. Then it will be important to have the correct junction lengths defined. <br /><br />Bottom line, the modeler doesn't HAVE to change the junction length if it is an unsteady flow model, but it would be good practice to do so (and it's easy to do).Chris G.https://www.blogger.com/profile/00354834185663924786noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-84124039060504529272009-07-10T14:44:30.564-07:002009-07-10T14:44:30.564-07:00Thanks for the quick response. I am currently rev...Thanks for the quick response. I am currently revieweing a HEC-RAS model and the person that set it up measured the distance through the junction for one reach, but measured the other reach only up to the junction itself. My question is what is the impact of them setting up the model this way? Should it be addressed?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-54669849809446871522009-07-10T14:21:03.733-07:002009-07-10T14:21:03.733-07:00Certainly. It is measured along the main channel ...Certainly. It is measured along the main channel flow path from the upstream cross section on the lower reach through the junction to the downstream cross section on the upper reach. You do this for both (all) reaches. And it is the same for steady or unsteady. Make sure you check my latest entry on junctions with regard to the new version of HEC-RAS soon to come out http://hecrasmodel.blogspot.com/2009/06/new-features-401-part-2junctions.htmlChris G.https://www.blogger.com/profile/00354834185663924786noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-58468450030077687462009-07-10T14:12:58.728-07:002009-07-10T14:12:58.728-07:00Can you please describe to me in detail how to mea...Can you please describe to me in detail how to measure the lengths across a junction. Do you measure from the most upstream cross-section through the junction to the downstream cross section for both reaches/rivers/ Or do you measure one through the junction and one to the junction. This is for an unsteady model. Thanks for the help.Anonymousnoreply@blogger.com