Q_out Problem

0Davinci0 · 2016-08-04 11:44:59

I am planning a measure for flood retention. I´ve created a precipitation runoff modell an got a Q_in (a graph) for my measure.

The big problem is that the Q_out simulated by Basement is unacceptable.
My total simulation time is 18.000 s. Every 180 s a Output should be written. After 15.000 s my measure is flooded. So in the timestep before my Q_out is zero. 180 s later Basement has simulated a Q_out of 7 m³/s. BUT in the next timestep (180 second later) the Output Q_out has a value of 0 m³/s.

In the following I´ve listed the Qin and Qout a part of the calculation and a part of my system settings (LOG Data). I´ve got NO idea what could be wrong with these settings.

TIME = 1.422000e+004 hyd. Time Step = 1.357083e-003 (SD: Wandersteinbach)
Qin[1] = 2.799999e+000 [m3/s] (Inflow)
Qout[2] = 4.065733e+000 [m3/s] (Outflow)
TIME = 1.440000e+004 hyd. Time Step = 1.353901e-003 (SD: Wandersteinbach)
Qin[1] = 3.000000e+000 [m3/s] (Inflow)
Qout[2] = 0.000000e+000 [m3/s] (Outflow)
TIME = 1.458000e+004 hyd. Time Step = 1.352632e-003 (SD: Wandersteinbach)
Qin[1] = 3.000000e+000 [m3/s] (Inflow)
Qout[2] = 3.958917e+000 [m3/s] (Outflow)
TIME = 1.476000e+004 hyd. Time Step = 1.352603e-003 (SD: Wandersteinbach)
Qin[1] = 3.000000e+000 [m3/s] (Inflow)
Qout[2] = 0.000000e+000 [m3/s] (Outflow)
TIME = 1.494000e+004 hyd. Time Step = 1.352602e-003 (SD: Wandersteinbach)
Qin[1] = 3.000000e+000 [m3/s] (Inflow)
Qout[2] = 3.954502e+000 [m3/s] (Outflow)
TIME = 1.512000e+004 hyd. Time Step = 1.352603e-003 (SD: Wandersteinbach)
Qin[1] = 3.000000e+000 [m3/s] (Inflow)
Qout[2] = 0.000000e+000 [m3/s] (Outflow)
TIME = 1.530000e+004 hyd. Time Step = 1.352603e-003 (SD: Wandersteinbach)
Qin[1] = 3.000000e+000 [m3/s] (Inflow)
Qout[2] = 7.960895e+000 [m3/s] (Outflow)
TIME = 1.548000e+004 hyd. Time Step = 1.352603e-003 (SD: Wandersteinbach)
Qin[1] = 3.000000e+000 [m3/s] (Inflow)
Qout[2] = 0.000000e+000 [m3/s] (Outflow)
TIME = 1.566000e+004 hyd. Time Step = 1.352603e-003 (SD: Wandersteinbach)
Qin[1] = 3.000000e+000 [m3/s] (Inflow)
Qout[2] = 0.000000e+000 [m3/s] (Outflow)
TIME = 1.584000e+004 hyd. Time Step = 1.352603e-003 (SD: Wandersteinbach)
Qin[1] = 3.000000e+000 [m3/s] (Inflow)
Qout[2] = 1.074445e+001 [m3/s] (Outflow)

GEOMETRY {
type = 2dm
file = Gewaesserstrecke UHV_kl_Triangle_entfernt.2dm
STRINGDEF {
node_ids = (1 2 3)
name = Inflow
upstream_direction = left
}
STRINGDEF {
name = Outflow
node_ids = (805 803 804 802 795 786 763 764 765 766)
upstream_direction = left
}
}
HYDRAULICS {
PARAMETER {
minimum_water_depth = 0.05
riemann_solver = exact
riemann_tolerance = 1.0e-6
simulation_scheme = exp
velocity_update_partial = volume_area
dynamic_depth_solver = on
geo_min_area_ratio = 0.05
geo_max_angle_quadrilateral = 45
geo_min_aspect_ratio = 0.06
}
FRICTION {
type = strickler
default_friction = 30
wall_friction = off
grain_size_friction = no
}
INITIAL {
type = dry
}
TURBULENCE_MODEL {
type = algebraic
kinematic_viscosity = 0.000001307
turbulence_factor = 3
const_eddy_viscosity = -1
boundary_gradient = zerogradient
}
BOUNDARY {
name = Inflow
string_name = Inflow
type = hydrograph
slope = 5
file = Q TEST.txt
max_interval = 20
number_of_iterations = 5000
weighting_type = conveyance
precision = -1.0
wse_calc_method = average
}
BOUNDARY {
name = Outflow
string_name = Outflow
type = zhydrograph
file = Outflow_WSE TEST.txt
inflow_possible = yes
zero_velocity = no
}
}
TIMESTEP {
total_run_time = 30000
start_time = -1.0
CFL = 0.95
minimum_time_step = 0.001
maximum_time_step = 100.0
initial_time_step = 1.0
ignore_wave_celerity = off
morph_cycle = off
}
OUTPUT {
console_time_step = 180
restart_time_step = 1E32
SPECIAL_OUTPUT {
type = balance
output_time_step = 180
balance_values = (timestep)
threshold_wse = -1000000
}

Kind regards,

David

0Davinci0 · 2016-08-04 18:46:44

I´ve got a warning, too. Till now I´ve ignored the warning, because the simulation works to the end.

*!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Warning !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*
*******************************************************************************
-> Mass conservation is not guaranteed! Negative water depth in element #869
(slope = 10.932).
missing volume to compensate the overdraft: 0.00954627

Could it be that my Q_out problem can be connected to this warning?

sajjad · 2016-08-04 20:11:37

I think u should change 'zhydrograph' bc at exit with 'hqrelation' or try 'zerogradient'. In flood studies, turbulence is known to exercise a relatively small influence, so u can turn it off. Good luck

User Forum of Software BASEMENT

#1 2016-08-04 11:44:59

Q_out Problem

#2 2016-08-04 18:46:44

Re: Q_out Problem

#3 2016-08-04 20:11:37

Re: Q_out Problem

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