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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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)
2
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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