No deltaz over a weir

lorenzo.scopetani · 2021-11-10 16:07:13

Good morning
I'm simulating a 2d sediment transport model and I've a weir inside my mesh.
I modelled the weir as a terrain modification, in one case applying the fixed bed and in another case not.
The results in both cases show 0 deltaz values near and on the weir.
Is the flow of sediment from upstream to downstream guaranteed in these situations? Is it only a problem caused by the high slope on the weir body?
I also selected the stringdef history for Qsed upstream and downstream the weir, but the .dat file shows not values. Could you give me some advice?
Thank you very much

Matteo Facchini · 2021-11-15 12:55:58

Hi Lorenzo
hard to say without seeing your mesh, but it could be that the flow conditions around/on the weir are below the transport threshold. You can try to run a simulation with a very large discharge value and see if the weir is eroded.
Cheers

lorenzo.scopetani · 2021-11-15 16:14:13

Thank for you reply.
I've already modeled with a very large values of Qinflow but I've tha same situation.
All material deposits upstream the weir, and the weir body doesn't erosion.
I've 0 deltaz, 0 Qsed, 0 grain bed load values.
I think I must model the weir absolutely with the block Inner boundary, because with the modified terrain I think the software can't generate erosion or deposition at the weir body, if there are small depth values and high velocities.
It's possible my opinion?
Thanks

Matteo Facchini · 2021-11-16 14:17:07

If you did not set any particular condition (e.g. particular roughness via MATID) on the weir body, the software sees it as a regular "bump" of sediment, so it should be erodible.

Can you copy paste your basement input file here?

lorenzo.scopetani · 2021-11-18 10:33:01

Good morning
I write the txt.file:

DOMAIN {
multiregion = unnamed_multiregion
BASEPLANE_2D {
region_name = Cutigliano
GEOMETRY {
type = 2dm
file = mesh2d.2dm
STRINGDEF {
name = inflow
node_ids = (73 7181 7770 234)
upstream_direction = right
}
STRINGDEF {
name = outflow
node_ids = (43 7404 4442 4500 42 4477 4452 4479 4447 4486 4467 4506 41 9654 4936 9664 4491 9802 7632 7637 4490 7641 7639 8008 40)
upstream_direction = right
}
}
HYDRAULICS {
PARAMETER {
simulation_scheme = exp
riemann_solver = exact
minimum_water_depth = 0.05
riemann_tolerance = 1.0e-6
velocity_update_partial = volume_area
dynamic_depth_solver = on
dynamic_depth_solver_precision = 0.005
geo_min_area_ratio = 0.05
geo_max_angle_quadrilateral = 45
geo_min_aspect_ratio = 0.06
}
FRICTION {
type = manning
input_type = index_table
wall_friction = on
index = (1 2 3 4 5)
friction = (0.06 0.07 0.035 0.23 0.06)
wall_friction_factor = 0.3
default_friction = 0.035
grain_size_friction = no
}
BOUNDARY {
name = reach-3
string_name = inflow
type = hydrograph
slope = 30
file = inflow - Copia (2).txt
max_interval = 20
number_of_iterations = 5000
weighting_type = conveyance
dynamic_slope = no
precision = -1.0
wse_calc_method = average
}
BOUNDARY {
name = outflow
type = hqrelation
slope = 30
string_name = outflow
weighting_type = conveyance
wall_flux = no
dynamic_slope = no
wse_calc_method = average
conveyance_type = tables
}
INITIAL {
type = continue
file = Cutigliano_restart.cgns
restart_solution_time = -1.0
}
TURBULENCE_MODEL {
type = algebraic
kinematic_viscosity = 0.000001307
const_eddy_viscosity = -1
turbulence_factor = 1
boundary_gradient = zerogradient
}
}
TIMESTEP {
CFL = 0.95
total_run_time = 34800
minimum_time_step = 0.001
start_time = 0
maximum_time_step = 100.0
initial_time_step = 1.0
ignore_wave_celerity = off
morph_cycle = off
}
OUTPUT {
console_time_step = 600
restart_time_step = 1E32
reference_time = 01-07-2021-00-00-00
SPECIAL_OUTPUT {
type = node_centered
format = sms
values = (depth velocity wse deltaz z_node)
output_time_step = 600
threshold_wse = -1000000
}
SPECIAL_OUTPUT {
type = BASEviz
output_time_step = 600
variable = depth
wse3D = off
vectors = off
gridlines = off
vectors_scaling_factor = 1.0
write_jpeg_image_time = -1.0
threshold_wse = -1000000
}
}
MORPHOLOGY {
BEDMATERIAL {
GRAIN_CLASS {
diameters = (236)
}
SOIL_DEF {
name = unique
tau_erosion_start = -1.0
LAYER {
mixture = unique
bottom_elevation = -0.5
}
}
SOIL_ASSIGNMENT {
index = (1 2 3 4 5)
soil = (unique unique unique unique unique)
type = index_table
}
MIXTURE {
name = unique
volume_fraction = (100)
}
}
INITIAL {
type = initial_mesh
}
BEDLOAD {
FORMULA {
bedload_formula = mpm
bedload_factor = 0.616
bedload_exponent = 1.5
theta_critical_approach = theta_critical_vanrijn
local_slope_correction = local_slope_vanrijn
critical_shear_stress_calibration = 1.0
bedforms_type = no_bedforms
}
PARAMETER {
limit_bedload_wetted = on
bedload_routing_start = 0.0
use_real_edge_lengths = off
use_cell_averaged_bedload_flux = off
}
BOUNDARY {
type = IODown
string_name = outflow
fraction_boundary = 1.0
}
BOUNDARY {
name = inflow
type = transport_capacity
string_name = inflow
mixture = unique
factor = 1.0
}
DIRECTION {
lateral_transport_type = lateral_bed_slope
lateral_index = (5)
lateral_transport_factor = 1.5
lateral_transport_exponent = 0.5
scale_lateral_transport = yes
}
}
PARAMETER {
porosity = 30
density = 2650
control_volume_type = constant
control_volume_thickness = (1 1 1 1 1)
control_volume_thickness_index = (1 2 3 4 5)
control_volume_initial = soildef
create_new_layers = off
min_theta_critic = 0.02
local_slope_angle_repose = 30.0
strong_coupling = off
distortion_offset = 0
distortion_time_interval = -1
}
GRAVITATIONAL_TRANSPORT {
index = (5)
angle_failure_dry = (35)
angle_failure_wetted = (15)
angle_failure_deposited = (5)
angle_wetted_criterion = fully_wetted
gravity_transport_on_cells = all
max_delta_z = 0.001
cycle_step = 5
min_changed_volume = 0.01
max_iterations = 10
only_subsurface_angle = no
check_hydrostatic_stabilization = no
stabilization_height = 0.00
}
}
}
PHYSICAL_PROPERTIES {
gravity = 9.81
viscosity = 1e-06
rho_fluid = 1000
}
PARALLEL {
number_threads = 1
}

But I think is better to send you the link with all file:

https://wetransfer.com/downloads/64071b … 524/40bdeb

Within the folder there is an image of my problem.
Thank you very much

Last edited by lorenzo.scopetani (2021-11-18 11:17:01)

Matteo Facchini · 2021-11-19 09:47:46

I am not quite sure what is happening, I see from your results that you have high velocity values over the weir, but no erosion whatsoever.

I would do some tests:

remove the turbulence model
use the IOUp upstream boundary condition for sediment transport and remove the gravitational transport

Cheers
Matteo

User Forum of Software BASEMENT

#1 2021-11-10 16:07:13

No deltaz over a weir

#2 2021-11-15 12:55:58

Re: No deltaz over a weir

#3 2021-11-15 16:14:13

Re: No deltaz over a weir

#4 2021-11-16 14:17:07

Re: No deltaz over a weir

#5 2021-11-18 10:33:01

Re: No deltaz over a weir

#6 2021-11-19 09:47:46

Re: No deltaz over a weir

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