Presentation by Octavio Sequeiros, Shell, Netherlands, at the XBeach User Day 2018, during Delft Software Days - Edition 2018. Thursday, 15 November 2018, Delft.
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DSD-INT 2018 Using XBeach for estimating wave conditions inside harbors - Sequeiros
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Wave in harbour modelling with XBeach
Study for Funchal (Madeira) and Santa Cruz (Tenerife)
Deltares XBeach User Day, 15th Nov 2018
Octavio E. Sequeiros
Metocean Team – Shell
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From offshore to nearshore wave conditions (shallow waters)
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Santa Cruz Tenerife
Funchal
Hindcast data from
nearest offshore data
point (Global Wavewatch
III Hindcast database).
Delft3D-WAVE
transformation modelling.
Refraction, shoaling,
white capping, bottom
friction effects.
2014 year transformed to
metocean data just
outside each harbour.
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Buoy
28.46 N, 16.23 W
Model
28.476 N, 16.225 W
Puertos del Estado buoy 1421, Santa
Cruz de Tenerife 2009-2017,
28.46 N, 16.23 W, at 56 m wd
Nearshore wave: model reality check with buoy data
Buoy
Model
0
5
10
15
20
25
30
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Frequency[%]
Hs [m]
Buoy Model
0
5
10
15
20
25
30
2 4 6 8 10 12 14 16 18 20
Frequency[%]
Tp [sec]
Buoy Model
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Tenerife – (within harbour)
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Instantaneous wave field in Santa Cruz, Tenerife
(30-min XBeach run for selected metocean state)
time
elevation(m)
point 1
0:00 0:05 0:10 0:15 0:20 0:25 0:30
-1.5
-1
-0.5
0
0.5
1
1.5
Santa Cruz berth location
XBeach software (wave-resolving, non-hydrostatic) to model
inner harbour waves (diffraction and reflection)
no_advec b.c.
Diffraction
Reflection
Refraction
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Funchal – (within harbour)
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XBeach output inner harbour conditions in Funchal
Max wave height in sea state
Instantaneous wave field
XBeach input as
boundary condition is
Delft3D nearshore output
Smaller harbour
But better positioned respect offshore wave climate
Better vessels location within harbour
Funchal berth location
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Conclusions
XBeach quite useful to estimate wave conditions inside harbour (under time and other constraints)
30-min long simulations for each sea state
Time step = 0.2 sec
Tenerife (nx = 445 ny = 635) → Computational time ~2-3 days in remote blade
Funchal (nx = 300 ny = 650) → Computational time ~2 days in remote blade
Solution to speed up. Run several simulations at the same time
Items to improve
Use cyclic boundary conditions on the side to avoid spurious reflection
Reassess inlet boundary condition water depth to better satisfy XBeach recommendations (e.g. best kd<1, not greater than 3)
Tenerife kd = 1.8-2.4
Funchal kd = 1.1-1.9
Use variable roughness to account for breakwater material
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