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#1 2023-08-08 16:03:28
- jakobs
- User
- Registered: 2023-06-08
- Posts: 3
Exterior bank erosion in a 180° bend due to curvature effect
Hello,
I am trying to model the lateral erosion and remeandering of a small river (Qmax = 3 m³/s).
Since I did not know how the curvature effect, lateral bed slope and gravitational transport behave, I decided to produce an artifical 180° bend with a slope of 0.001 and 0.025 and test the single transport options.
The options I did choose are:
- curvature effect dynamic, radius calculation type = velocity vectors, curvature transport factor = 7.0
- lateral bed slope, lateral transport factor = 1.5
- gravitational transport: phi = 35° (for dry, wetted and deposited soil)
I expected to have lateral erosion on the exterior bank and deposition on the interior bank, however this only happens for the first hour. If I continue the simulation the interior bank starts to erode completely and the exterior bank remains more or less the same. It seems to me, that some lateral erosion on the exterior bank is occuring, but the material is not deposited on the interior bank. Instead, the interior bank starts to erode, due to a lack of sediment input from the exterior bank.
Are there any experiences with Basement on how to promote this type of lateral erosion? Or are there experiences in modelling river meanderization with Basement?
Best regards,
Jakob
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#2 2024-06-12 10:06:36
- Matthias Bürgler
- Developer
- From: Zürich
- Registered: 2019-04-04
- Posts: 175
Re: Exterior bank erosion in a 180° bend due to curvature effect
Hi Jakob,
We have a very similar test case to test the capability of BASEMENT to reproduce the point bars occuring in such bends.
For the BASEHPC (previously BASEMENTv3), such a test case was featured in the most recent publication (see Test T4 in the Results section), which is freely available here:
https://www.sciencedirect.com/science/a … 4815221001
The same test case was also used in the PhD thesis of Vonwiller (2018) with BASEMD and the results were in good agreement with experiments (see Section 8.2). The thesis freely available here: https://www.research-collection.ethz.ch … /1/246.pdf
I recently tried to reproduce this test case with BASEMD and got reasonable results. Here is the model.json for that test:
{
"SETUP": {
"BASEMD": {
"multiregion": "struiksma",
"BASEPLANE_2D": [
{
"GEOMETRY": {
"file": "Uchannel_coarse.2dm",
"type": "2dm",
"STRINGDEF": [
{
"name": "inflow",
"node_ids": [
4,
6316,
6304,
6257,
6456,
6261,
6459,
5083,
6245,
6243,
6254,
6220,
6233,
6237,
5
],
"upstream_direction": "right"
},
{
"name": "outflow",
"node_ids": [
122,
6184,
6447,
6167,
6169,
6445,
6063,
6179,
6174,
6193,
6137,
6189,
6138,
123
],
"upstream_direction": "left"
}
]
},
"HYDRAULICS": {
"FRICTION": {
"default_friction": 0.01,
"grain_size_friction": "no",
"type": "chezy",
"wall_friction": "off"
},
"INITIAL": {
"type": "continue",
"file": "../../initMor/run/struiksma_flume_restart.h5",
"restart_solution_time": -1.0
},
"PARAMETER": {
"dynamic_depth_solver": "on",
"dynamic_depth_solver_precision": 0.005,
"geo_max_angle_quadrilateral": 45,
"geo_min_area_ratio": 0.05,
"geo_min_aspect_ratio": 0.06,
"minimum_water_depth": 0.001,
"riemann_solver": "exact",
"riemann_tolerance": 1e-06,
"simulation_scheme": "exp",
"velocity_update_partial": "volume_area"
},
"BOUNDARY": [
{
"type": "hydrograph",
"number_of_iterations": 5000,
"precision": 0.1,
"string_name": "inflow",
"file": "inflow.txt",
"slope": 2,
"dynamic_slope": "no",
"max_interval": 20,
"weighting_type": "area",
"wse_calc_method": "average"
},
{
"type": "hqrelation",
"string_name": "outflow",
"slope": 2,
"conveyance_type": "tables",
"dynamic_slope": "no",
"wall_flux": "no",
"weighting_type": "area",
"wse_calc_method": "average"
}
]
},
"OUTPUT": {
"console_time_step": 100.0,
"restart_time_step": 1e+32,
"SPECIAL_OUTPUT": [
{
"output_time_step": 10.0,
"threshold_wse": -1000000.0,
"type": "boundary_history",
"boundary_values": [
{
"accumulator": "none",
"value": "Q"
},
{
"accumulator": "none",
"value": "Qsed"
},
{
"accumulator": "integrate",
"value": "Qsed"
}
],
"flush_all_num_steps": 0,
"history_one_file": "yes"
},
{
"output_time_step": 100.0,
"threshold_wse": -1000000,
"type": "element_centered",
"format": "vtk",
"values": [
{
"accumulator": "none",
"value": "wse"
},
{
"accumulator": "none",
"value": "velocity"
},
{
"accumulator": "none",
"value": "z_element"
},
{
"accumulator": "none",
"value": "tau"
},
{
"accumulator": "none",
"value": "grain_size"
},
{
"accumulator": "none",
"value": "depth"
},
{
"accumulator": "none",
"value": "bedload_vec"
}
],
"split_file": "no"
}
]
},
"TIMESTEP": {
"CFL": 0.9,
"ignore_wave_celerity": "off",
"initial_time_step": 0.001,
"maximum_time_step": 100,
"minimum_time_step": 0.001,
"morph_cycle": "off",
"start_time": 0.0,
"total_run_time": 24000.1
},
"region_name": "ribberink_flume",
"MORPHOLOGY": {
"BEDMATERIAL": {
"GRAIN_CLASS": {
"diameters": [
1
]
},
"MIXTURE": [
{
"name": "mixture1",
"volume_fraction": [
100
]
}
],
"SOIL_ASSIGNMENT": {
"index": [
1
],
"soil": [
"soil1"
],
"type": "index_table"
},
"SOIL_DEF": [
{
"name": "soil1",
"tau_erosion_start": -1,
"LAYER": [
{
"bottom_elevation": -5.0,
"mixture": "mixture1"
}
]
}
]
},
"INITIAL": {
"type": "initial_mesh"
},
"PARAMETER": {
"control_volume_initial": "soildef",
"control_volume_type": "constant",
"create_new_layers": "off",
"density": 2650,
"distortion_offset": 0,
"distortion_time_interval": -1,
"local_slope_angle_repose": 30,
"min_theta_critic": 0.02,
"porosity": 40.0,
"strong_coupling": "off",
"control_volume_thickness": [
0.0097
],
"control_volume_thickness_index": [
1
]
},
"BEDLOAD": {
"FORMULA": {
"bedforms_type": "no_bedforms",
"bedload_factor": 0.5,
"bedload_formula": "mpm",
"local_slope_correction": "no_local_slope",
"bedload_exponent": 1.5,
"theta_critical": [
0.047
],
"critical_shear_stress_calibration": 1.0,
"theta_critical_approach": "theta_critical_vanrijn",
"theta_critical_hiding": "mean",
"theta_critical_index": [
1
]
},
"PARAMETER": {
"bedload_routing_start": 0,
"limit_bedload_wetted": "on",
"use_cell_averaged_bedload_flux": "off",
"use_real_edge_lengths": "off"
},
"BOUNDARY": [
{
"string_name": "inflow",
"type": "IOUp",
"mixture": "mixture1",
"name": "inflow_sed",
"fraction_boundary": 1.0
},
{
"string_name": "outflow",
"type": "IODown",
"name": "outflow_sed",
"fraction_boundary": 1.0
}
],
"DIRECTION": [
{
"lateral_index": [
1
],
"lateral_transport_type": "lateral_bed_slope",
"lateral_transport_factor": 1.4,
"lateral_transport_exponent": 0.5,
"scale_lateral_transport": "yes"
},
{
"lateral_index": [
1
],
"lateral_transport_type": "curvature_effect_dynamic",
"curvature_transport_factor_type": "fix",
"curvature_transport_factor": 11.0,
"update_timestep_radius": 10.0,
"initial_radius": 10000.0,
"min_abs_radius": 2.0,
"min_abs_radius_use": "significance_value",
"radius_calculation_type": "velocity_vectors"
}
]
}
}
}
]
},
"simulation_name": "struiksma_test_v28"
}
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