15.28. Seagrass#

This case aims at reproducing flume experiments of Ganthy et al. [2015].

These experiments were conducted in a recirculating straight flume for five contrasted seagrass development stages (T1 to T5) and a case without vegetation (Ts) and four flow regimes (V1 to V4), leading to twenty four velocity profiles measured 0.45 m downward the leading edge of vegetation patch.

../_images/test_cases_seagrass_description.png — Description of the experiment modelled with SEAGRASS test case#

To run this test case, first modify CPP options (cppdefs.h) :

# define SEAGRASS
# undef REGIONAL

#elif defined SEAGRASS
/*
!                       Seagrass example
!                       ================
*/
# define OBSTRUCTION

# undef  OPENMP
# undef  MPI
# define SOLVE3D
# define UV_ADV
# define UV_COR
# define NONLIN_EOS
# define SALINITY
# define ANA_GRID
# define MASKING
# define ANA_INITIAL
# define ANA_SMFLUX
# define ANA_STFLUX
# define ANA_SSFLUX
# define ANA_SRFLUX
# define ANA_BTFLUX
# define ANA_BSFLUX
# define GLS_MIXING
# define PSOURCE
# undef  PSOURCE_MASS
# define ANA_PSOURCE
# define NS_PERIODIC
# undef  FLOATS
# define NO_FRCFILE
# define USE_CALENDAR
# define NEW_S_COORD
# define OBC_EAST
# define FRC_BRY
# ifdef FRC_BRY
#  define ANA_BRY
#  define Z_FRC_BRY
#  define OBC_M2CHARACT
#  define OBC_REDUCED_PHYSICS
#  define M2_FRC_BRY
#  undef  M3_FRC_BRY
#  define T_FRC_BRY
# endif
# undef  RVTK_DEBUG

#endif

Settings :

The test case correspond to a 2DV case. The water depth is around 0.20 m discretized with 40 sigmas layers. The spatial resolution is 0.05 m and the domain is 1.8 m long.

For each test (T1 to T5 and Ts) and flow regime (V1 to V4 corresponding to speed from 0.1 to 0.4 m/s), the model was run during 3 minutes. An equilibrium state was reach on average after 1 minute. Results are outputted at 1 Hz over the last 30 seconds of the run and then time-averaged.

All parameters for T4V4 configuration are available in TEST_CASES directory in files :

croco.in.Seagrass : CROCO parameters, current speed is forced by river input
obstruction_seagrass_para.txt : OBSTRUCTION module parameters, see OBSTRUCTION main parameter file for more details about parameters
obstruction_seagrass_var.txt : seagrass parameters, see variable specific file for more details about parameters
obstruction_seagrass_position.nc : seagrass position, see position file format for more details
obstruction_seagrass_distri.txt : seagrass vertical distribution, see vertical distribution file format for more details

Please refer to Ganthy et al. [2015], Ganthy et al. [2024] and Ganthy [2011] for details for the others configurations.

Results :