Abnormal boundary flow velocity of NBQ

[hqcmax]

Hello, dear users of Croco. When I open NBQ and BRY_FRC, standing waves will form at the boundaries and the flow velocity will be very high. At the beginning, the range formed is approximately the default sponge layer (10 grids). Later, it will spread within the area. I would like to ask, is this a problem with the sponge layer settings or nudging?And I’m quite curious. When I open nudging, do I have to use CLIMATOLOGY? Is it using the clim file boundaries for nudging?

• Below is my cpp setting scheme:
• REGIONAL
  RUN_NBQ_test
  MPI
  NBQ
  W_HADV_WENO5
  W_VADV_WENO5
  NBQ_PRECISE
  CURVGRID
  SPHERICAL
  MASKING
  WET_DRY
  NEW_S_COORD
  TIDES
  M2FILTER_NONE
  SSH_TIDES
  UV_TIDES
  POT_TIDES
  TIDERAMP
  OBC_EAST
  OBC_NORTH
  USE_CALENDAR
  UV_HADV_WENO5
  UV_VADV_WENO5
  TS_HADV_WENO5
  TS_VADV_WENO5
  UV_MIX_S
  UV_VIS2
  UV_VIS_SMAGO
  TS_DIF2
  TS_MIX_GEO
  TS_MIX_IMP
  GLS_MIXING
  GLS_KOMEGA
  ANA_PSOURCE
  PSOURCE
  PSOURCE_NCFILE
  PSOURCE_NCFILE_TS
  SOLVE3D
  UV_COR
  UV_ADV
  SALINITY
  NONLIN_EOS
  BULK_FLUX
  TEMPERATURE
  LIMIT_STFLX_COOLING
  GUSTINESS
  BULK_LW
  ONLINE
  ERA_ECMWF
  BULK_MONTH_1DIGIT
  DOUBLE_PRECISION
  FRC_BRY
  Z_FRC_BRY
  OBC_M2CHARACT
  OBC_REDUCED_PHYSICS
  M2_FRC_BRY
  M3_FRC_BRY
  T_FRC_BRY
  OBC_M3ORLANSKI
  OBC_TORLANSKI
  ZCLIMATOLOGY
  M2CLIMATOLOGY
  M3CLIMATOLOGY
  TCLIMATOLOGY
  ZNUDGING
  M2NUDGING
  M3NUDGING
  TNUDGING
  SPONGE
  LIMIT_BSTRESS
  ANA_BSFLUX
  ANA_BTFLUX
  AVERAGES
  AVERAGES_K
  TRACERS
  M3FAST
  NBQ_IMP
  HZR
  NBQ_MASS
  NBQ_HZCORRECT
  OBC_NBQ
  OBC_NBQORLANSKI
  OBC_WORLANSKI
  NBQ_NUDGING
  NBQCLIMATOLOGY
  NBQ_FRC_BRY
  W_FRC_BRY
  VAR_RHO_2D
  SPLIT_EOS
  VIS_COEF_3D
  NTRA_T3DMIX
  SPONGE_GRID
  SPONGE_DIF2
  SPONGE_VIS2
  CUBIC_INTERP
  NF_CLOBBER
  BD_EXCHANGE
  ENDDOLOOP2D
  DOLOOP2D_R
  DOLOOP2D

U:

V:

• I haven’t studied this aspect deeply enough. I hope to receive explanations from relevant scholars. Thank you.

[swapnil]

Hi,

skip my previous reply (you may receive mail).

because it’s already Hz(IendR+1).

add # include “nbq.h” after this line 3132 in analytical.F
change:
line 3180 (analytical.F)
wnbqbry_east(j,k)=0. to wnbqbry_east(j,k)=qdmw_nbq(Iend,j,k)
line 3218
wnbqbry_north(i,k)=0. to wnbqbry_north(i,k)=qdmw_nbq(i,Jend,k)

and VISC2_NBQ in croco.in increase it 0.01 to 500 (example)
set sponge values (50000. 500.) TauM_in 3. to 20.
remove SPONGE_GRID from cppdefs.h

I will check these issues again this weekend.

Sorry. thank you.

best regards,

[hqcmax]

Thank you for your patient explanation. Next, I will modify VISC2_NBQ and try it after closing SPONGE_GRID. I have another small question. There is no variable named “qdmw_nbq” in my boundary file. Is this w or pressure?Thank you again.

[swapnil]

Hi,

Ok.

grep -R qdmw_nbq (inside ocean OCEAN folder)

enable the tide with this and test it.

ifdef TIDES
 define SSH_TIDES
 define UV_TIDES
 define M2FILTER_NONE
  ifndef UV_TIDES
   define OBC_REDUCED_PHYSICS
  endif
 define POT_TIDES
define TIDERAMP
endif

try twice with and without OBC_REDUCED_PHYSICS

and share your before and after plot. Thank you.

Best regards

[hqcmax]

Thank you for your explanation. Based on your guidance, I attempted the following operations, all of which were carried out with hot start under the “define NBQ” mode. First, I modified VISC2_NBQ from the default value of 0.01 to 10, but found no effect. Then, on this basis, I undef OBC_REDUCED_PHYSICS, and found that the abnormal flow velocity at the boundary disappeared, and the water level also changed. However, I’m not sure if this is a correct simulation after turning it off, although the abnormal standing wave disappeared. The other operations you guided, such as undefine SPOHGE_GRID and modifying some parts of the content in analytical.F, have not been attempted yet. Thank you for your explanation, and I am extremely grateful!
define OBC_REDUCED_PHYSICS

undef OBC_REDUCED_PHYSICS