coheceive sediment concentration negative error

[gegujang@lycos.co.kr]

It's so hard to define InterfaceSedimentWater and Free vertical movement

My InterfaceSedimentWater.dat

<begin_rugosity>
INITIALIZATION_METHOD : CONSTANT
DEFAULTVALUE : 0.0025
<end_rugosity>

<begin_critical_shear_erosion>
INITIALIZATION_METHOD : CONSTANT
DEFAULTVALUE : 0.05
<end_critical_shear_erosion>

<begin_critical_shear_deposition>
INITIALIZATION_METHOD : CONSTANT
DEFAULTVALUE : 0.02
<end_critical_shear_deposition>

<begin_erosion_rate>
INITIALIZATION_METHOD : CONSTANT
DEFAULTVALUE : 0.00005
<end_erosion_rate>

<beginproperty>
NAME : cohesive sediment
UNITS : kg/m2
DESCRIPTION : cohesive sediment mass
PARTICULATE : 1
WATER_FLUXES : 1
EROSION : 1
DEPOSITION : 1
MASS_LIMITATION : 1
MASS_MIN : 1e-8
INITIALIZATION_METHOD : CONSTANT
DEFAULTVALUE : 10.
TIME_SERIE : 1
BOX_TIME_SERIE : 0
OUTPUT_HDF : 1
<endproperty>


And Free Vertical Movement.dat

<beginproperty>
NAME : cohesive sediment
WS_TYPE : 2
SALTINT : 1
SALTINTVALUE : 3
CHS : 4
KL : .006
KL1 : .01
ML : 4.65
M : 1
FREEVERT_IMPEXP_ADV : 0
WS_VALUE : 0.00001
<endproperty>

Why coheceive sediment conc. negative In 75 116 1 cell error message accur?


I am working model for 1 years.

Model calc Dt = 60sec

Saving Time = 1days

[luis_at_mohid.com]

Hi,

Well, no one has ever said it's easy to model sediment transport
The probable cause for your problem is the time step.
What is the horizontal resolution of your model?
What are the maximum velocities in your domain?
Reduce your time step in order to reduce the Courant number for transport. You can also compute cohesive sediment transport (advection-diffusion) using an implicit time discretization (ADVECTION_H_IMP_EXP : 0 in the cohesive sediment property block in WaterProperties input data file) , which can also help.
Also, you should have some idea (from data or calibration) of the critical shear stresses for deposition and erosion, reference rates for erosion, and settling velocity.

Hope this helps,
Luis