open TELEMAC-MASCARET The mathematically superior suite of solvers

HI all,

I am modelling a telemac2d model coupled with GAIA for a river. My upstream boundary is prescribed discharge and my downstream boundary is prescribed water elevation. My sediment type is 6 non-cohesive sediment and I included bed load and suspended load in my model. However, during the simulation, unreasonable sediment enters from my downstream boundary (boundary 1) and it causes significant deposition at one point.
BALANCE OF NCOH SEDIMENT1 (UNIT: g/l * M3)

INITIAL QUANTITY : 0.4355562E-02
FINAL QUANTITY : 0.4355409E-02
BOUNDARY 1 FLUX: 0.3652729E+09 ( >0 : ENTERING <0 : EXITING )
BOUNDARY 2 FLUX: -0.000000 ( >0 : ENTERING <0 : EXITING )
TOTAL QUANTITY LOST : 0.3264203E-06
RELATIVE ERROR : 0.7494333E-04
JACOBI: 1 ITERATIONS, RELATIVE PRECISION = 4.2686634887550485E-035
CVTRVF (BIEF): 1 SUB-ITERATIONS
GRACJG (BIEF) : 0 ITERATIONS, RELATIVE PRECISION: 0.1309357E-15

BALANCE OF NCOH SEDIMENT2 (UNIT: g/l * M3)

INITIAL QUANTITY : 55120.29
FINAL QUANTITY : 55119.85
BOUNDARY 1 FLUX: 0.4040069E+15 ( >0 : ENTERING <0 : EXITING )
BOUNDARY 2 FLUX: -0.000000 ( >0 : ENTERING <0 : EXITING )
TOTAL QUANTITY LOST : 0.6268370
RELATIVE ERROR : 0.1137217E-04
JACOBI: 1 ITERATIONS, RELATIVE PRECISION = 0.0000000000000000
CVTRVF (BIEF): 1 SUB-ITERATIONS
GRACJG (BIEF) : 0 ITERATIONS, RELATIVE PRECISION: 0.1309569E-15

BALANCE OF NCOH SEDIMENT3 (UNIT: g/l * M3)

INITIAL QUANTITY : 251933.4
FINAL QUANTITY : 251931.1
BOUNDARY 1 FLUX: 0.2024456E+16 ( >0 : ENTERING <0 : EXITING )
BOUNDARY 2 FLUX: -0.000000 ( >0 : ENTERING <0 : EXITING )
TOTAL QUANTITY LOST : 3.254018
RELATIVE ERROR : 0.1291619E-04
JACOBI: 1 ITERATIONS, RELATIVE PRECISION = 3.1809770527395037E-020
CVTRVF (BIEF): 1 SUB-ITERATIONS
GRACJG (BIEF) : 0 ITERATIONS, RELATIVE PRECISION: 0.1305480E-15

BALANCE OF NCOH SEDIMENT4 (UNIT: g/l * M3)

INITIAL QUANTITY : 373045.3
FINAL QUANTITY : 373041.6
BOUNDARY 1 FLUX: 0.3136625E+16 ( >0 : ENTERING <0 : EXITING )
BOUNDARY 2 FLUX: -0.000000 ( >0 : ENTERING <0 : EXITING )
TOTAL QUANTITY LOST : 5.194513
RELATIVE ERROR : 0.1392462E-04
JACOBI: 1 ITERATIONS, RELATIVE PRECISION = 4.8359639807893276E-035
CVTRVF (BIEF): 1 SUB-ITERATIONS
GRACJG (BIEF) : 0 ITERATIONS, RELATIVE PRECISION: 0.1307955E-15

BALANCE OF NCOH SEDIMENT5 (UNIT: g/l * M3)

INITIAL QUANTITY : 375013.8
FINAL QUANTITY : 375009.9
BOUNDARY 1 FLUX: 0.3173136E+16 ( >0 : ENTERING <0 : EXITING )
BOUNDARY 2 FLUX: -0.000000 ( >0 : ENTERING <0 : EXITING )
TOTAL QUANTITY LOST : 5.355424
RELATIVE ERROR : 0.1428061E-04
JACOBI: 1 ITERATIONS, RELATIVE PRECISION = 4.4244712636375870E-035
CVTRVF (BIEF): 1 SUB-ITERATIONS
GRACJG (BIEF) : 0 ITERATIONS, RELATIVE PRECISION: 0.1329737E-15

BALANCE OF NCOH SEDIMENT6 (UNIT: g/l * M3)

INITIAL QUANTITY : 14013.70
FINAL QUANTITY : 14013.63
BOUNDARY 1 FLUX: -0.5781347E+14 ( >0 : ENTERING <0 : EXITING )
BOUNDARY 2 FLUX: -0.000000 ( >0 : ENTERING <0 : EXITING )
TOTAL QUANTITY LOST : 0.4783178E-01
RELATIVE ERROR : 0.3413215E-05
What I tried:
Reduced the time step and change fixed time step
Reduced my active layer thickness
All of them are not working. I attached my slf file of GAIA, the history of the simulation, and the screenshot of the downstream boundary.

Regards
LIN

Sorry I forgot to attach the history and cas files.

You probaly need to refine the mesh at the boundary, sediment transport models require detailed attention in this area by creator.

Hope that helps,

Patrick

Hello Patrick,

Thank you for your advice. The problem was fixed when I refined the mesh near the boundary. Thank you for your help.

Regards
LIN