Difference between revisions of "INLET TEST CASE"

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<div class="title">Inlet Test Case</div>
<div class="title">Inlet Test Case</div>


This coupled example demonstrates the significance of wave-current coupling and includes ROMS coupled to SWAN. The application and methodology was originally developed and implemented as decribed in Warner, Perlin, and Skyllingstad (2008) "Using the Model Coupling Toolkit to couple earth system models", Environmental Modelling & Software, 23, p. 1240-1249.
'''Input Files:''' [[media:Inlet_test_config.zip| zip file with complete inputs ]], tested with ROMS SVN version 291.


'''Output Files:'''  [[media:INLET_TEST_SVN_R291_Ocean_his.nc | history file (ocean_his.nc) ]], produced by ROMS SVN version 291.


The test case is a simple tidal inlet system, based on a rectangular basin domain that is 15 km wide by 14 km in length, with a uniform initial depth of 4 m. Model setup parameters are shown in Table 1. The domain is separated into two regions. The seaward (top) region has northern, western, and eastern edges that are open with radiation boundary conditions. The backbarrier region (bottom) is enclosed with four walls and is connected to the seaward region through a 2 km wide inlet. The model is forced by a tide and waves. An oscillating water level is imposed on the northern edge with a tidal amplitude of 1 m. Waves are also imposed on the northern edge with a height of 1 m, directed to the south with a period of 10s.


In the paper  as
This test case couples ROMS and [[SWAN]] directly using the Modeling Coupling Toolkit (MCT) library. To run this application the user needs to activate [[Options#INLET_TEST|INLET_TEST]]. It only can be run in distributed-memory (MPI) since the parallel threads are split to run both ROMS and SWAN at the same time. This test illustrates the
The model is run with two configurations: 1) one-way coupled with wave information passed to the circulation model and 2) two-way fully coupled where the ocean model sends water velocities, water level, and bottom morphologic change to the wave model, and the wave model sends wave height, period, and wave length to the ocean model. The model hydrodynamics were simulated for a period of 2 days with a morphologic scale factor of 10, simulating a 20 day period.
significance of wave-current coupling. This application and coupling methodology is described in [[Bibliography#WarnerJC_2008a|Warner ''et al.'' (2008)]].
In the one-way coupled system, wave heights evolve to a steady state, decreasing southward toward the inlet and showing no effect from the inlet currents (Figure 3). The contour of wave height is straight across the inlet opening showing no sign of current interaction. At the peak of the ebb tide the combined wave-current bottom stresses are maximum near the location of maximum currents. As the tidal currents transport sediment and evolve the sea floor, the bathymetric evolution produces flood and ebb tidal shoals, with a larger ebb shoal. By contrast for the the two-way coupled model results, the wave heights are greatly increased in front of the inlet. The wave height contour lines show increased wave amplitudes in the inlet as the approaching wave interacts with an opposing current. The increased wave heights create combined bottom stresses that are greater than the one-way coupled system, and the peak bottom stresses are located near the maximum wave heights. The morphology evolves a stronger ebb shoal due to the higher stresses and the shoal is displaced slightly further seaward. The coupling of the wave and ocean models demonstrates an important feature that the nearshore wave and circulation dynamics are mutually interactive and accurate modeling of this type of system should include these communications.


(Figure )
This test case models and idealized tidal inlet system. The model domain is a 15x14 km rectangle with a uniform initial depth of 4 m. The model setup parameters are shown in the table below. The domain is separated into two regions: the seaward (top) and back-barrier (bottom) regions. The seaward region is open with radiation conditions on the western, northern and eastern edges. The back-barrier region is enclosed with four walls and is connected to the seaward region through a 2 km wide inlet. The model is forced by a tide and waves. An oscillating water level is imposed on the northern edge with a tidal amplitude of 1 m. Waves are also imposed on the northern edge with a height of 1 m, directed to the south with a period of 10s.


Table 1. Model parameters for the ROMS-SWAN test case 1.


Model Parameter Variable Value
length, width, depth Xsize, Esize, depth 15000 m, 14000 m, 4.0 m
number of grid spacings Lm, Mm, Nm 75, 70, 10
bottom roughness zob 0.015 m
time step dt 10 s
simulation steps Ntimes 17280 steps (2 day)
morphology factor morph_fac 10 (= 20 day scaled simulation)
settle velocity ws 11.0 mm s-1
erosion rate E0 5x10-3 kg m-2 s-1
critical stresses cd, ce 0.10 N m-2
porosity  0.50
bed thickness bed_thick 10.0 m
northern edge tide A, Tt 1.0 m, 12 hour
northern edge wave height Hsig 2m
northern edge wave period T 10 s
northern edge wave direction  from 00


Table 1. Important model parameters:
{| border="1" cellspacing="0" cellpadding="5" align="center"
!Model Parameter
!Variable
!Value
|-
|length, width, depth
|[[Variables#Xsize|Xsize]], [[Variables#Esize|Esize]], [[Variables#hmax|hmax]]
|15000 m, 14000 m, 4.0 m
|-
|number of grid spacings
|[[Variables#Lm|Lm]], [[Variables#Mm|Mm]], [[Variables#N|N]]
|75, 70, 10
|-
|bottom Roughness
|[[Variables#Zob|Zob]]
|0.015 m
|-
|time step
|[[Variables#dt|dt]]
|10 s
|-
|simulation steps
|[[Variables#ntimes|ntimes]]
|17280 steps (2 days)
|-
|morphology factor
|[[Variables#morph_fac|morph_fac]]
|10 (=20 day scaled simulation)
|-
|grain size
|[[Variables#Sd50|Sd50]]
|0.10 mm
|-
|settle velocity
|[[Variables#Wsed|Wsed]]
|11.0 mm s<sup>-1</sup>
|-
|erosion rate
|[[Variables#Erate|Erate]]
|5 x 10<sup>-3</sup> kg m<sup>-2</sup>s<sup>-1</sup>
|-
|critical stress
|[[Variables#tau_cd|tau_cd]], [[Variables#tau_ce|tau_ce]]
|0.10 Nm<sup>-2</sup>
|-
|porosity
|[[Variables#poros|poros]]
|0.50
|-
|bed thickness
|[[Variables#bed|bed(:, :, :, ithck)]]
|10.0 m
|-
|northern edge tide
|A, T<sub>t</sub>
|1.0 m, 12 h
|-
|northern edge wave height
|H<sub>sig</sub>
|2 m
|-
|northern edge wave period
|T
|10 s
|-
|northern edge wave direction
|&theta;
|from 0&deg; (from North)
|-
|}


cpp options:
Below we provide a brief example of the model output.
To compile this test case the user is required to activate:
 
SWAN_COUPLING ?= on
[[Image:Inlet_test_zeta_day0.5.png|thumb|850px|none|<center><b>Figure 1:</b> ROMS output of free surface and barotropic currents at t=0.5 days.</center>]]
MPI ?= on
 
 
[[Image:Inlet_test_Hwave_day0.5.png|thumb|850px|none|<center><b>Figure 2:</b> SWAN output of wave height (Hwave, m) and barotropic currents.</center>]]
 
[[Image:Inlet_test_final_bed.png|thumb|850px|none|<center><b>Figure 3:</b> Final bed_thickness after 2.0 days.  Time series are from locations of maximum erosion and deposition.</center>]]

Latest revision as of 16:56, 9 January 2009

Inlet Test Case

Input Files: zip file with complete inputs , tested with ROMS SVN version 291.

Output Files: history file (ocean_his.nc) , produced by ROMS SVN version 291.


This test case couples ROMS and SWAN directly using the Modeling Coupling Toolkit (MCT) library. To run this application the user needs to activate INLET_TEST. It only can be run in distributed-memory (MPI) since the parallel threads are split to run both ROMS and SWAN at the same time. This test illustrates the significance of wave-current coupling. This application and coupling methodology is described in Warner et al. (2008).

This test case models and idealized tidal inlet system. The model domain is a 15x14 km rectangle with a uniform initial depth of 4 m. The model setup parameters are shown in the table below. The domain is separated into two regions: the seaward (top) and back-barrier (bottom) regions. The seaward region is open with radiation conditions on the western, northern and eastern edges. The back-barrier region is enclosed with four walls and is connected to the seaward region through a 2 km wide inlet. The model is forced by a tide and waves. An oscillating water level is imposed on the northern edge with a tidal amplitude of 1 m. Waves are also imposed on the northern edge with a height of 1 m, directed to the south with a period of 10s.


Table 1. Important model parameters:

Model Parameter Variable Value
length, width, depth Xsize, Esize, hmax 15000 m, 14000 m, 4.0 m
number of grid spacings Lm, Mm, N 75, 70, 10
bottom Roughness Zob 0.015 m
time step dt 10 s
simulation steps ntimes 17280 steps (2 days)
morphology factor morph_fac 10 (=20 day scaled simulation)
grain size Sd50 0.10 mm
settle velocity Wsed 11.0 mm s-1
erosion rate Erate 5 x 10-3 kg m-2s-1
critical stress tau_cd, tau_ce 0.10 Nm-2
porosity poros 0.50
bed thickness bed(:, :, :, ithck) 10.0 m
northern edge tide A, Tt 1.0 m, 12 h
northern edge wave height Hsig 2 m
northern edge wave period T 10 s
northern edge wave direction θ from 0° (from North)

Below we provide a brief example of the model output.

Figure 1: ROMS output of free surface and barotropic currents at t=0.5 days.


Figure 2: SWAN output of wave height (Hwave, m) and barotropic currents.
Figure 3: Final bed_thickness after 2.0 days. Time series are from locations of maximum erosion and deposition.
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