Drag Force estimation over a bicycle in PYTHON

AIM : Program in PYTHON to calculate drag force against a cyclist .

1) Program to plot velocity v/s drag force.

2) Program to plot drag coefficients v/s drag forces.

THEORY : Drag is the resistance attributed to an object, in this case its air resistance . It is a product of an objects drag cofficient (cd) , density of the fluid ( ρ), square of its velocity ( v^2)and its size , critically its frontal area ( area ).

D = 1/2 * ρ*v^2 * area * cd

source link : https://www.cyclingpowerlab.com/CyclingAerodynamics.aspx

PYTHON CODE :

1) velocity v/s drag force :

""" PROGRAM TO FIND THE DRAG FORCE OVER A BICYCLE ( VELOCITY V/S DRAG FORCE) """

import matplotlib.pyplot as plt                                # importing the plotting features from liberary matplotlib 

# INPUTS

rho = 1.225                                                    # density of air in kg/m^3
area = 0.32                                                    # frontal area in m^2
c_d = 0.88                                                     # coefficient of drag 
velocities = [10,20,30]
dragforces = []                                                # saving the values in an array          
for velocity in velocities:
	dragforces.append((0.5*c_d*area*rho*velocity*velocity))    # all calculated velocities are appended into the drag froce

# GRAPH PLOTS 

plt.plot(velocities,dragforces)
plt.xlabel('velocity')
plt.ylabel('drag')
plt.show()

GRAPH :

2) drag coefficients v/s drag forces :

"""PROGRAM TO FIND THE DRAG FORCE OVER A BICYCLE ( DRAG FORCE v/s DRAG COEEFICIENT)"""

import matplotlib.pyplot as plt                      # importing the plotting features from liberary matplotlib 

# INPUTS

c_ds = [1.15,1,0.88,0.70]                            # coefficient of drag for different positions 
area = 0.32                                          # frontal area in m^2
rho = 1.225                                          # density of air in kg/m^3 
velocity = 120                     
dragforces = []                                  
for c_d in c_ds:
	dragforces.append((0.5*c_d*area*rho*velocity*velocity))  # appending the values of c_d into dragforces

# GRAPH PLOTS 

plt.plot(dragforces,c_ds)
plt.xlabel('Drag forces')
plt.ylabel('Drag coefficient')
plt.show()

GRAPH :

ERRORS :

correction : line 7 : change c_d into c_ds