Storm Water Detention Tank with Two Orifices for Outflow

import math

# constants

dt = 10.0**(-5.0)

Qin = 5.0

H = 10.0
Abase = 25.0

D1 = 0.5
y1 = 1.0

D2 = 0.75
y2 = 3.5

tf = 30.0

g = 9.81
Cd = 0.62

##################################

# derived constants

R1 = D1/2.0
R2 = D2/2.0

A1 = math.pi*(R1**2.0)
A2 = math.pi*(R2**2.0)

##################################

t = 0.0
y = 0.0             # water level

while t <= tf:

    if y > y1:
        v1 = Cd*math.sqrt(2.0*g*(y - y1))
        Q1 = A1*v1
    else:
        Q1 = 0.0

    if y > y2:
        v2 = Cd*math.sqrt(2.0*g*(y - y2))
        Q2 = A2*v2
    else:
        Q2 = 0.0

    Qout = Q1 + Q2

    Qnet = Qin - Qout

    # Qnet*dt = Abase*dy

    dy = Qnet*dt/Abase

    y = y + dy

    t = t + dt

####################################

print y
print ""

# y2 = 0.5*g*(t2**2.0)

t2 = math.sqrt(2.0*y2/g)

xf = v2*t2

print xf

#>>> 
#4.83150056172     # final water depth

#2.67686345291     # range from orifice 2
#>>>