model unstable for Storage area in unsteady flow

[sanjeewa]

Hi,
I am solving an unsteady flow by method: I Included Storage area for my model. I setup the storage area using hec geo RAS and set the elevation versus volume curve using compute E-V table from terrain option.

When I triggered a computation, it’s got unstable and following errors appeared.

Can you please advise me to solve this problems?

thank you very much..
Greetings!

[Anonymous]

If the storage area elevation versus volume curve is really steep at the beginning, it might cause instability when the storage area first gets any inflow. Is your storage area starting out dry? Does the storage area need to go down all the way to 40.77 elevation?

As an experiment, get ride of the first 8 rows or so. Make 41.9 have a volume of “0” and see if it helps.

41.9 0
41.99 1.76
42.05 3.75

[cameron]

If you don’t include the storage area, is the model stable? How is the storage area connected to the model? If by lateral structure, what is the weir coefficient.

[Anonymous]

Thank you for your reply. Storage area was starting out with dry. I corrected as your comments.Then again error message appeared that mentioned minimum level should be 40.77( as in the geometry).

regards

sanjeewa

[Anonymous]

Thank you for reply. I connected model and storage area through the lateral Structures and weir coefficient is 1.1. When I considered the Area time depth method (storage area ) model was run for some extent. But instability occurred at bridges structures.

“Minimum error exceeds allowable tolerance ” at downstream section of structure and few others section also.

Kind regards

sanjeewa

[Author]

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