Drag force against a cyclist

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

Parameters:

c_d = 0.9

A = 0.1m²

v = 1-60 m/s

% to calculate the drag force for cyclist
clear all
close all
clc

%input
%coefficient of drag
c_d = 0.9

%density in kg/m3
rho = 1.2

%area in m2
A = 0.1

%velocity in m/s
v = [1:60];


%to calculate the drag force

drag_force = c_d*rho*A*v.^2*0.5;

plot(v,drag_force)
grid on
xlabel('Velocity(m/s)')
ylabel('Drag Force (N)')

Case-II

Program to plot Drag Co-efficient vs Drag force

c_d = 0.1 - 0.9

A = 0.1m²

v = 10 m/s

% to calculate the drag force for cyclist
clear all
close all
clc

%input
%coefficient of drag
c_d = [0.1,0.9]

%density in kg/m3
rho = 1.2

%area in m2
A = 0.1

%velocity in m/s
v = 10;


%to calculate the drag force

drag_force = c_d*rho*A*v.^2*0.5;

plot(c_d,drag_force);
grid on
xlabel('Drag Coefficient')
ylabel('Drag Force (N)')

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.