286 lines
14 KiB
Python
286 lines
14 KiB
Python
# import modules for general use
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import os # to import functions from other folders
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import sys # to import functions from other folders
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from logging import \
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exception # to throw an exception when a specific condition is met
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import numpy as np
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#importing pressure conversion function
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current = os.path.dirname(os.path.realpath(__file__))
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parent = os.path.dirname(current)
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sys.path.append(parent)
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from functions.pressure_conversion import pressure_conversion
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def FODE_function(x_out,h,A,A_a,p,rho,g):
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# (FODE ... first order differential equation)
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# describes the change in outflux velocity from a reservoir
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# based on the outflux formula by Andreas Malcherek
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# https://www.youtube.com/watch?v=8HO2LwqOhqQ
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# adapted for a pressurized pipeline into which the reservoir effuses
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# and flow direction
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# see documentation in word-file
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# x_out ... effusion velocity
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# h ... level in the reservoir
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# A_a ... Area_outflux
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# A ... Area_reservoir_base
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# g ... gravitational acceleration
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# rho ... density of the liquid in the reservoir
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f = x_out*abs(x_out)/h*(A_a/A-1.)+g-p/(rho*h)
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return f
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class Ausgleichsbecken_class:
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# units
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# make sure that units and display units are the same!
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# units are used to label graphs and disp units are used to have good formatting when using pythons print()
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area_unit = r'$\mathrm{m}^2$'
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area_outflux_unit = r'$\mathrm{m}^2$'
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density_unit = r'$\mathrm{kg}/\mathrm{m}^3$'
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flux_unit = r'$\mathrm{m}^3/\mathrm{s}$'
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level_unit = 'm'
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pressure_unit = 'Pa' # !DO NOT CHANGE! needed for pressure conversion
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time_unit = 's'
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velocity_unit = r'$\mathrm{m}/\mathrm{s}$'
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volume_unit = r'$\mathrm{m}^3$'
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area_unit_disp = 'm²'
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area_outflux_unit_disp = 'm²'
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density_unit_disp = 'kg/m³'
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flux_unit_disp = 'm³/s'
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level_unit_disp = 'm'
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# pressure_unit_disp will be set within the __init__() method
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time_unit_disp = 's'
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velocity_unit_disp = 'm/s'
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volume_unit_disp = 'm³'
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g = 9.81 # m/s² gravitational acceleration
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# init
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# see docstring below
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def __init__(self,area,area_outflux,timestep,pressure_unit_disp,level_min=0,level_max=np.inf,rho = 1000.):
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"""
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Creates a reservoir with given attributes in this order: \n
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Base Area [m²] \n
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Outflux Area [m²] \n
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Simulation timestep [s] \n
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Pressure unit for displaying [string] \n
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Minimum level [m] \n
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Maximum level [m] \n
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Density of the liquid [kg/m³] \n
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"""
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#set initial attributes
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self.area = area # base area of the cuboid reservoir
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self.area_out = area_outflux # area of the outlet towards the pipeline
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self.density = rho # density of the liquid in the system
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self.level_min = level_min # lowest allowed water level - warning yet to be implemented
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self.level_max = level_max # highest allowed water level - warning yet to be implemented
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self.pressure_unit_disp = pressure_unit_disp # pressure unit for displaying
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self.timestep = timestep # timestep in the time evolution method
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# initialize for get_info() (if get_info() gets called before set_steady_state() was ever executed)
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# is also used to check if set_steady_state() was ever executed
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self.influx = -np.inf
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self.outflux = -np.inf
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self.level = -np.inf
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self.pressure = -np.inf
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self.volume = -np.inf
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# setter - set attributes
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def set_initial_level(self,initial_level):
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# sets the initial level in the reservoir and should only be called during initialization
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if self.level == -np.inf:
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self.level = initial_level
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self.update_volume(set_flag=True)
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else:
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raise Exception('Initial level was already set once. Use the .update_level(self,timestep,set_flag=True) method to update level based on net flux.')
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def set_initial_pressure(self,initial_pressure):
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# sets the initial static pressure present at the outlet of the reservoir and should only be called during initialization
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if self.pressure == -np.inf:
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self.pressure = initial_pressure
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else:
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raise Exception('Initial pressure was already set once. Use the .update_pressure(self) method to update pressure based on current level.')
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def set_influx(self,influx):
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# sets influx to the reservoir in m³/s
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# positive influx means that liquid flows into the reservoir
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self.influx = influx
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def set_outflux(self,outflux,display_warning=True):
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# sets outflux to the reservoir in m³/s
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# positive outflux means that liquid flows out of reservoir the reservoir
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if display_warning == True:
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print('You are setting the outflux from the reservoir manually. \n \
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This is not an intended use of this method. \n \
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Refer to the timestep_reservoir_evolution() or set_steady_state() method instead.')
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self.outflux = outflux
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def set_level(self,level,display_warning=True):
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# sets level in the reservoir in m
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if display_warning == True:
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print('You are setting the level of the reservoir manually. \n \
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This is not an intended use of this method. \n \
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Refer to the update_level() or set_steady_state() method instead.')
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self.level = level
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def set_pressure(self,pressure,display_warning=True):
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# sets pressure in the pipeline just below the reservoir in Pa
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if display_warning == True:
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print('You are setting the pressure below the reservoir manually. \n \
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This is not an intended use of this method. \n \
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Refer to the update_pressure() or set_steady_state() method instead.')
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self.pressure = pressure
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def set_volume(self,volume,display_warning=True):
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# sets volume in reservoir
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if display_warning == True:
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print('You are setting the volume in the reservoir manually. \n \
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This is not an intended use of this method. \n \
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Refer to the .update_volume() or set_initial_level() or set_steady_state() method instead.')
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self.volume = volume
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def set_steady_state(self,ss_influx,ss_level):
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# set the reservoir to steady state (ss) condition in which the net flux is zero
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# set pressure acting on the outflux area so that the level stays constant
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ss_outflux = ss_influx
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ss_influx_vel = abs(ss_influx/self.area)
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ss_outflux_vel = abs(ss_outflux/self.area_out)
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# see word document for explaination on how to arrive at the ss pressure formula
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ss_pressure = self.density*self.g*ss_level+self.density*ss_outflux_vel*(ss_influx_vel-ss_outflux_vel)
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# use setter methods to set the attributes to their steady state values
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self.set_influx(ss_influx)
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self.set_initial_level(ss_level)
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self.set_initial_pressure(ss_pressure)
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self.set_outflux(ss_outflux,display_warning=False)
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# getter - return attributes
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def get_info(self, full = False):
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# prints out the info on the current state of the reservoir
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# full = True gives more info
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new_line = '\n'
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if self.pressure != np.inf:
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p = pressure_conversion(self.pressure,self.pressure_unit,self.pressure_unit_disp)
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if self.outflux != np.inf:
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outflux_vel = self.outflux/self.area_out
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if full == True:
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# :<10 pads the self.value to be 10 characters wide
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print_str = (f"The cuboid reservoir has the following attributes: {new_line}"
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f"----------------------------- {new_line}"
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f"Base area = {self.area:<10} {self.area_unit_disp} {new_line}"
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f"Outflux area = {round(self.area_out,3):<10} {self.area_outflux_unit_disp} {new_line}"
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f"Current level = {self.level:<10} {self.level_unit_disp}{new_line}"
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f"Critical level low = {self.level_min:<10} {self.level_unit_disp} {new_line}"
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f"Critical level high = {self.level_max:<10} {self.level_unit_disp} {new_line}"
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f"Volume in reservoir = {self.volume:<10} {self.volume_unit_disp} {new_line}"
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f"Current influx = {round(self.influx,3):<10} {self.flux_unit_disp} {new_line}"
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f"Current outflux = {round(self.outflux,3):<10} {self.flux_unit_disp} {new_line}"
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f"Current outflux vel = {round(outflux_vel,3):<10} {self.velocity_unit_disp} {new_line}"
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f"Current pipe pressure = {round(p,3):<10} {self.pressure_unit_disp} {new_line}"
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f"Simulation timestep = {self.timestep:<10} {self.time_unit_disp} {new_line}"
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f"Density of liquid = {self.density:<10} {self.density_unit_disp} {new_line}"
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f"----------------------------- {new_line}")
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else:
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# :<10 pads the self.value to be 10 characters wide
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print_str = (f"The current attributes are: {new_line}"
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f"----------------------------- {new_line}"
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f"Current level = {self.level:<10} {self.level_unit_disp}{new_line}"
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f"Current volume = {self.volume:<10} {self.volume_unit_disp} {new_line}"
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f"Current influx = {round(self.influx,3):<10} {self.flux_unit_disp} {new_line}"
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f"Current outflux = {round(self.outflux,3):<10} {self.flux_unit_disp} {new_line}"
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f"Current outflux vel = {round(outflux_vel,3):<10} {self.velocity_unit_disp} {new_line}"
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f"Current pipe pressure = {round(p,3):<10} {self.pressure_unit_disp} {new_line}"
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f"----------------------------- {new_line}")
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# print the info to console
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print(print_str)
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def get_current_influx(self):
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return self.influx
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def get_current_outflux(self):
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return self.outflux
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def get_current_level(self):
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return self.level
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def get_current_pressure(self):
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return self.pressure
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def get_current_volume(self):
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return self.volume
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# update methods - update attributes based on some parameter
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def update_level(self,timestep,set_flag=False):
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# update level based on net flux and timestep by calculating the volume change in
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# the timestep and then convert the new volume to a level by assuming a cuboid reservoir
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# there is no call of the update_volume() function because I need the updated level from half a timestep in the reservoir evolution
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# if update_volume() was called within this function, the script would produce wrong results.
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net_flux = self.influx-self.outflux
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delta_level = net_flux*timestep/self.area
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level_new = (self.level+delta_level)
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# raise exception error if level in reservoir falls below 0.01 ######################### has to be commented out if used in loop
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if level_new < 0.01:
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raise Exception('Reservoir ran emtpy')
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# set flag is necessary because update_level() is used to get a halfstep value in the time evoultion
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if set_flag == True:
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self.set_level(level_new,display_warning=False)
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elif set_flag == False:
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return level_new
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def update_pressure(self,set_flag=False):
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# update pressure based on level and flux velocities
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# see word document for explaination
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influx_vel = abs(self.influx/self.area)
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outflux_vel = abs(self.outflux/self.area_out)
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p_new = self.density*self.g*self.level+self.density*outflux_vel*(influx_vel-outflux_vel)
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# set flag for consistency with update_level()
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if set_flag ==True:
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self.set_pressure(p_new,display_warning=False)
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elif set_flag == False:
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return p_new
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def update_volume(self,set_flag=False):
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volume_new = self.level*self.area
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# set flag for consistency with update_level()
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if set_flag == True:
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self.set_volume(volume_new,display_warning=False)
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elif set_flag == False:
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return volume_new
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#methods
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def timestep_reservoir_evolution(self):
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# update outflux, level, pressure and volume based on current pipeline pressure and waterlevel in reservoir
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# solve the FODE of the outflux velocity for one timestep using explicit four step Runge-Kutta method
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# get some variables
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dt = self.timestep
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rho = self.density
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g = self.g
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A = self.area
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A_a = self.area_out
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yn = self.outflux/A_a # outflux velocity
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h = self.level
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h_hs = self.update_level(dt/2)
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p = self.pressure
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p_hs = self.pressure + rho*g*(h_hs-h)
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# perform explicit 4 step Runge Kutta
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Y1 = yn
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Y2 = yn + dt/2*FODE_function(Y1,h,A,A_a,p,rho,g)
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Y3 = yn + dt/2*FODE_function(Y2,h_hs,A,A_a,p_hs,rho,g)
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Y4 = yn + dt*FODE_function(Y3,h_hs,A,A_a,p_hs,rho,g)
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ynp1 = yn + dt/6*(FODE_function(Y1,h,A,A_a,p,rho,g)+2*FODE_function(Y2,h_hs,A,A_a,p_hs,rho,g)+ \
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2*FODE_function(Y3,h_hs,A,A_a,p_hs,rho,g)+ FODE_function(Y4,h,A,A_a,p,rho,g))
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# set/update the attributes to their new values
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self.set_outflux(ynp1*A_a,display_warning=False)
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self.update_level(dt,set_flag=True)
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self.update_volume(set_flag=True)
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self.update_pressure(set_flag=True)
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