Wave-current Interaction (WEC) in the COAWST Modeling System

Nirnimesh Kumarwith John Warner, George Voulgaris, Maitane

Olabarrieta

*see Kumar et al., 2012 (third paper in your booklet) : Implementation of the vortex force formalism in the coupled ocean-atmosphere-wave-sediment transport (COAWST) modeling system for inner shelf and surf zone applications, Ocean Modelling, Volume 47, 2012, Pages 65-95, 10.1016/j.ocemod.2012.01.003.*also see Olabarrieta et al., 2012 (fourth paper for applications)

Wave-averaged Equations

S tz z

tzz

Sz

ACC HA

H u H u u H u H u u H vt y y

ux

vx

�������������� �

c

St st st Sts z z z z s

z

s

VA

v u uu H f v H f v H H vs xs x

uy s

� ��������������

COR StCOR PG HVF����������������������������������������������������� ���� ������������������������������������������

' '

z

xz z

wz

BF BA RA BtSt SuSt HM VM

v uu w

s H sH H DH

�������������� �

������������������������������������������������������������������ �����

F F

�������������� �

Wave-Current Interaction Description

StCOR Stokes-Coriolis Force/Hasselmann Stress

PG Pressure Gradient (Includes Bernoulli head, quasi-static pressure and vertical vortex force, Eqn. 5, 7, 9 and 13)

HVF Horizontal Vortex Force

BA+RA Breaking & Roller Acceleration (Wave dissipation and roller induced flows)

BtSt+SuSt Bottom & Surface Streaming (Can act as stress in bottom and surface layer)

Exchange of Data Field

http://woodshole.er.usgs.gov/operations/modeling/COAWST/index.html

cppdefs.h (COAWST/ROMS/Include)WEC_MELLOR+ Activates the Mellor (2011) method for WEC

WEC_VF(preferred method for 3D)

Activate WEC using the Vortex Force formalism (Uchiyama et al., 2010)

Wave-current Interaction (WEC)

WEC_MELLOR(Mellor, 2011)

WEC_VF(Uchiyama et al., 10)

+ Roller Model+ Streaming

+ Dissipation (depth)+ Roller Model + Wave mixing + Streaming

Implemented in Kumar et al., 2011

Implemented in Kumar et al., 2012

*Processes in italics are optional

Dissipation (Depth-limited wave breaking)WDISS_THORGUZA Use depth-limited wave dissipation based on Thornton

and Guza (1983). See Eqn. (31), pg-71

WDISS_CHURTHOR Activate depth-limited wave dissipation based on Church and Thornton (1993). See Eqn. (32), pg-71

WDISS_WAVEMODActivate wave-dissipation from a wave model. If using SWAN wave model, use INRHOG=1 for correct units of wave dissipation

Note: (a) Use WDISS_THORGUZA/CHURTHOR if no information about wave dissipation is

present, and you can’t run the wave model to obtain depth-limited dissipation

(b)If you do not define any of these options, and still define WEC_VF, the model expects a forcing file with information about dissipation

ROLLER MODEL (for Wave Rollers)ROLLER_SVENDSEN Activate wave roller based on Svendsen (1984). See

Warner et al. (2008), Eqn. 7 and Eqn. 10.

ROLLLER_MONO Activate wave roller for monochromatic waves from REF-DIF. See Haas and Warner, 2009.

ROLLER_RENIERS Activate wave roller based on Reniers et al. (2004). See Eqn. 34-37 (Advection-Diffusion)

Note: (a)If defining ROLLER_RENIERS, you must specify the parameter

wec_alpha (αr in Eqn. 34, varying from 0-1) in the INPUT file. Here 0 means no percentage of wave dissipation goes into creating wave rollers, while 1 means all the wave dissipation creates wave rollers.

Wave breaking induced mixing

TKE_WAVEDISSZOS_HSIG

• Activate enhance vertical viscosity mixing from waves within framework of GLS. See Eq. 44, 46 and 47.

• The parameter αw in Eq. 46 can be specified in the INPUT file as ZOS_HSIG_ALPHA (roughness from wave amplitude)

• Parameter Cew in Eqn. 47 is specified in the INPUT file as SZ_ALPHA (roughness from wave dissipation)

Note: Sensitivity tests for wave-mixing were done in Kumar et al. (2012). The enhanced mixing is sensitive to Cew

Bottom and Surface Streaming

BOTTOM_STREAMING

Bottom streaming due to waves using Uchiyama et al. (2010) methodology. See Eqn. 22-26. This method requires dissipation due to bottom friction. If not using a wave model, then uses empirical Eq. 22.

BOTTOM_STREAMING_XU_BOWEN

Bottom streaming due to waves based on methodology of Xu and Bowen, 1994. See Eq. 27.

SURFACE_STREAMINGSurface streaming using Xu and Bowen, 1994. See Eq. 28.

Note: (a) BOTTOM_STREAMING_XU_BOWEN was tested in Kumar et al. (2012). It requires

very high resolution close to bottom layer. Suggested Vtransform=2 and Vstretching=3

[0,0]

[1000,-12]

z

x

y

Hsig= 2mTp = 10sθ = 10o

Shoreface Test Case (Obliquely incident waves on a planar beach)

Wave field computed using SWAN One way coupling (only WEC) Application Name: SHOREFACE Header file: COAWST/ROMS/Include/shoreface.h Input file: COAWST/ROMS/External/ocean_shoreface.in

Header File (COAWST/ROMS/Include)

Input File (COAWST/ROMS/External)

Input File (COAWST/ROMS/External)

Requires a wave forcing fileas one way coupling only

WEC Related Output

Dissip_roller / Eqn. 37rollA / Eqn. 35Zetaw / Eqn. 7qsp / Eqn. 9bh / Eqn. 5

Forcing file for one way coupling Data/ROMS/Forcing/swan_shoreface_angle_forc.nc

Should contain the following variables

Wave Height Hwave

Wave Direction Dwave

Wave Length Lwave

Bottom Orbital Vel. Ub_Swan

Depth-limited breaking Dissip_break

Whitecapping induced breaking Dissip_wcap

Bottom friction induced dissip. Dissip_fric

Time Period Pwave_top/Pwave_bot

Code Compilation:coawst.bash

./coawst.bash –j N

Application Name

Number of Nested Grids

ROOT and Project Directory

Define Message Passage Interface (MPI), Fortran Compiler, NETCDF4

Header (*.h) &Analytical (ana_*.h)Files

Running the Shoreface Test Casenp = number of processorscoawstM = Executable created after compilationInput file = ROMS/External/ocean_shoreface.in

Serial./coawstS.exe ROMS/External/ocean_shoreface.in

Parallelmpiexec/run -np 4 ./coawstM.exe ROMS/External/ocean_shoreface.in

Results (I of III)Significant Wave Height

Sea surface elevation

Results (II of III)Depth-averaged Velocities

Cross-shore Vel. Longshore Vel.

Results (III of III)

Cross-shore

Longshore

Vertical

Eulerian Stokes

WEC related Diagnostics Terms(i.e., contribution to momentum balance)

Terms in momentum balance Definition Output Variable

Local Acc. u_accel/ ubar_accel

Horizontal Advection u_hadv/ubar_hadv

Vertical Advection

u_vadv

Coriolis Force u_cor/ubar_cor

Stokes-Coriolis u_stcor/ubar_stcorPressure Gradient

u_prsgrd/ubar_prsgrd

Vortex Force u_hjvf/ubar_hjvf

Vortex Force u_vjvf

Terms in momentum balance Definition Output Var.

(see Eqn. 21)Breaking + Roller Acceleration + Streaming

u_wbrk/ubar_wbrk u_wrol/ubar_wrolu_bstm/ubar_bstm u_sstm/ubar_sstm

BREAKING THE PRESSURE GRADIENT TERM

Pressure Gradient u_prsgrd/ubar_prsgrd

Eulerian Contribution ubar_zeta

Quasi-static response, Eqn. 7 ubar_zetw

Bernoulli-head contribution, Eqn. 5 ubar_zbeh

Surface pressure boundary, Eqn. 9 ubar_zqsp

Inlet Test Case (WEC in a tidal inlet) Wave field computed using

SWAN Two way coupling (WEC

and CEW) Application Name:

INLET_TEST Header file:

COAWST/Projects/Inlet_test/Coupled/inlet_test.h

Input file: COAWST/Projects/Inlet_test/Coupled/ocean_inlet_test.in

COAWST/Projects/Inlet_test/Coupled/swan_inlet_test.in

COAWST/Projects/Inlet_test/Coupled/coupling_inlet_test.hSOUTH

NORTH

Header File (COAWST/Projects/Inlet_test/Coupled)

Input File (COAWST/Projects/Coupled/ocean_inlet_test.in

ROMS/Functionals/ana_fsobc.h

Input File (COAWST/Projects/Coupled/swan_inlet_test.in

INRHOG should be 1 for correct units of wave dissipation

Example of TEST CommandTEST 120{}TEST 0

Input File (COAWST/Projects/Coupled/swan_inlet_test.in

Input File (COAWST/Projects/Coupled/coupling_inlet_test.in

Code Compilation:coawst.bash

./coawst.bash –j N

Running the Inlet_Test Casenp = number of processorscoawstM = Executable created after compilationInput file = Projects/Inlet_Test/Coupled/coupling_inlet_test.in

Serial./coawstS.exe Projects/Inlet_test/Coupled/coupling_inlet_test.in

Parallelmpiexec/run -np 4 ./coawstM.exe Projects/Inlet_test/Coupled/coupling_inlet_test.in

ResultsHsig

ReferencesKumar et al., 2012: Implementation of the vortex force formalism in the coupled ocean-atmosphere-wave-sediment transport (COAWST) modeling system for inner shelf and surf zone applications, Ocean Modelling, Volume 47, 2012, Pages 65-95, 10.1016/j.ocemod.2012.01.003.

Kumar et al., 2011: Implementation and modification of a three-dimensional radiation stress formulation for surf zone and rip-current applications, Coastal Engineering, Volume 58, Issue 12, December 2011, Pages 1097-1117, 10.1016/j.coastaleng.2011.06.009.

Olabarrieta, M., J. C. Warner, and N. Kumar (2011), Wave-current interaction in Willapa Bay, J. Geophys. Res., 116, C12014, doi:10.1029/2011JC007387.

Warner et al., 2008: Development of a three-dimensional, regional, coupled wave, current, and sediment-transport model, Computers & Geosciences, Volume 34, Issue 10, October 2008, Pages 1284-1306, ISSN 0098-3004, 10.1016/j.cageo.2008.02.012.

Haas and Warner, 2009: Comparing a quasi-3D to a full 3D nearshore circulation model: SHORECIRC and ROMS, Ocean Modelling, Volume 26, Issues 1–2, 2009, Pages 91-103, ISSN 1463-5003, 10.1016/j.ocemod.2008.09.003.