Tidal Scenario – Boundary Condition

[MAC]

What is the best way to simulate a tidal boundary condition?

I am modelling a crossing over a stream which outfalls to a beach. The crossing very close to the beach. I have run a steady state model, entering a Known Water Surface level as the downstream boundary condition- is this sufficient?

I have also tried to run an unsteady model with stage hydrograph as downstream boundary, but the model develops serious instabilities. I have tried artificially extending the downstream length of the model, but this just exacerbates the instabilities!

[Rodrigo Perdigão]

Hi, MAC

I’m dealing with the same issue. Did you find any help?

[Luis Partida]

The unsteady simulation will give you the most accurate results assuming you have low and high tide data. As far as stabilizing that model, there are endless possibilities, check your HTab and time step compared to your cross section spacing.

The steady state model will give you your most conservative answer in that at high tide of X elevation, my worst case scenario for impacts, or whatever your scope, it would be Z.

[Author]

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