Re: [Anuga-user] Simulation of bores

[Gareth D. <gar...@gm...>]

Just adding to Steve's boundary-condition point here -- which I agree 
with -- I have seen problematic models where the incoming stage was 
specified along with zero momentum. This can cause severe reductions in 
wave-height near the boundary if the true momentum is not negligible 
(e.g. typical situation for an offshore tsunami boundary condition). The 
boundary condition Steve mentions should not do that.


On 14/5/19 1:01 pm, Stephen Roberts wrote:
>
> Hi Ananth,
>
>
> I would suggest looking at the boundary condition  for the Okushiri 
> validation  test
>
>
> validation_tests/experimental_data/okushiri, in particular the use of
>
>
> Bts = 
> anuga.Transmissive_n_momentum_zero_t_momentum_set_stage_boundary(domain, 
> wave_function)
>
>
>
> Also you might try the more accurate (though slower algorithm), DE1 
> instead of DE0, via a call to
>
>
> domain.set_flow_algorithm('DE1')
>
>
> How are you setting the BC at the moment?
>
>
> Cheers
>
> Steve
>
>
> ==============================
> Stephen Roberts
> Undergraduate Convenor
> Mathematical Sciences Institute
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> ------------------------------------------------------------------------
> *From:* Ananth Wuppukondur <a.w...@uq...>
> *Sent:* Wednesday, 8 May 2019 7:17:46 PM
> *To:* anu...@li...
> *Subject:* [Anuga-user] Simulation of bores
> Hi,
>
> I'm simulating tsunami bores in ANUGA in a 9m long flume with stage 
> and x momentum as input. The attached figure shows comparison of 
> simulations with experimental measurements as well as another 
> numerical model BASEMENT which is similar to ANUGA. Black lines are 
> experimental measurements, red -ANUGA results and blue - BASEMENT 
> results. If we see at the results, the simulations are underpredicted 
> by upto 50% within a 8m reach in both the numerical models compared to 
> experiments. The first curve is the input condition for the model and 
> we can see that even the queried results at the input location are not 
> simulated properly in the models to match with the given boundary 
> conditions. The results are similar for different bore heights and 
> velocities.
>
> Also, if we look at the duration of the bore, it is around 3sec with a 
> falling limb behind peak elevation. Instead of a falling limb behind 
> the peak elevation, if I extend the duration of the peak elevation to 
> 2 sec followed by a falling limb (making total duration of bore 5sec), 
> the dissipation in the simulation results is not much compared to 
> earlier case, which suggests this is something to do with duration of 
> peak elevation in the bore.
>
> Could you please suggest why there is huge dissipation of wave height 
> in simulation of bores? The still water depth was 0.13m and bore 
> height was around 7cm at the input.
>
> Best regards,
>
> Ananth.
>
>
> /
> /
>
> //
>
> *Ananth Wuppukondur*
>
> B.Tech, M.S (by Research)
>
> PhD Candidate
>
> School of Civil Engineering
>
> The University of Queensland
>
> Brisbane Qld 4072 Australia
>
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>
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