To calculate drag force against a cyclist in Python

Aim:

To calculate drag force against a cyclist.

Objective:-

• To write a program to plot Velocity vs Drag force.
• To write a program to plot Drag Co-efficient vs Drag force.

Introduction :

Drag is the force of wind or air resistance pushing in the opposite direction to the motion of the object, in this case, the cyclist.

Frontal Area:

Frontal area is the area you see if you look at a cyclist from the front. Reducing this area means that there are fewer collisions with the wind.

Drag Coefficient:

The drag coefficient is a number that aerodynamicists use to model all of the complex dependencies of shape, inclination, and flow conditions on aircraft drag.

Any object moving through a fluid experiences drag - the net force in the direction of flow due to pressure and shear stress forces on the surface of the object.

The drag force can be expressed as:

F_d = c_d 1/2 ρ v² A

where

F_d = drag force (N)

c_d = drag coefficient

ρ = density (1.2 kg/m³ for air )

v = flow velocity (m/s)

A = characteristic frontal area of the body (m²)

Program:

Case-I

Program to plot Velocity vs Drag force

#program to calculate the drag force 
#Inputs

import matplotlib.pyplot  as plt

#drag co-efficients 

c_d = 0.8

#frontal area in m^2
A = 0.1

#Density in kg/m^#
rho = 1.2

#Velocity in m/s
velocities = [5,6,7,10,11,15]
drag_force = []

for velocity in velocities:
	drag_force.append((0.5*rho*velocity*velocity*A*c_d))

plt.plot(velocities,drag_force)

plt.xlabel('Velocity(m/s)')
plt.ylabel('Drag Force(N)')
plt.show()

Case-II

Program to plot Drag Co-efficient vs Drag force

#program to calculate the drag force 
#Inputs
import math 
import matplotlib.pyplot  as plt

#velocity in m/s

velocity = 8

#frontal area in m^2
A = 0.1

#Density in kg/m^#
rho = 1.2

#drag coeeficient
C = [0.5,0.7,0.8]

drag_force = []

for c in C :
	drag_force.append(0.5*rho*velocity*velocity*A*c)

plt.plot(C,drag_force)

plt.xlabel('Drag co-efficient')
plt.ylabel('Drag Force(N)')
plt.show()

Conclusion:

Case I : Drag force is increasing w.r.t. the velocity .

Case II: Plot shows the linear variation between the Drag coefficient & Drag force.