modeling buildings in HEC-RAS 2D

[Ahmed Adel]

Hello every one

I am simulating a flash flood. it passes through multi-buildings
I don’t know how to represent these areas
should it be (storage area, Ineffective area, weir takes circular shape around the building, or something else)

All suggestions are highly appreciated?

[user]

Try to assign higher Manning’s N value to the buildings in the 2D flow areas.

[Robert]

Hello,

If you solve your model using 2D, so the better solution is using of dtm with buildings (https://www.google.sk/search?q=dtm+with+buildings&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwif94qq27LKAhUDCBoKHUyhAv0QsAQIHQ&biw=1600&bih=775#imgrc=zRnzZ5PB8ERc-M%3A)

Mrs. User suggested to use higher n-values. But when you use higher n-values, so your flooding area will be incorret. Using higher n-values (also ineffective areas) are good solution for 1D modelling.

regards
Robert

[Ahmed Adel]

Thank you “user” for your support.

Also, I believe that Robert provided a solution more suitable for my problem.
best wishes Robert and User

[PaoloP]

I’m not completely agree that delete the area occupied by buildings is the best solution.

If the inside of the buildings can be flooded using the high n number (eg. 10) in the buildings area could well represent this phenomenon. The hydrodinamic (velocity) around the buildings will not be so different in the 2 approaches.

To define high n value in the buildings area you need to define the mesh elements exactly around the specific areas.

At the end, if you already have the DTM with the buildings it will be easier to use directly the DTM, if you have to modify the DTM to include the buildings, probably define the higher n value could be better.

Paolo

[Author]

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