Program to calculate drag force against a cyclist using MATLAB

Program to calculate drag force against a cyclist using MATLAB

The plot of drag force vs velocity

Density of air = 1.225kg/m^3

Front area = 0.5m^2

Drag coefficient = 0.85

In this, the velocity is increasing from 1m/s to 22m/s at an increment of 2m/s

% program for calculating the drag force on the bicycle
close all
clear all
clc

% Input
%drag_coefficient
c_d = 0.85;

%area m^2
a = 0.5;

%density kg/m^3
rho = 1.225;

% velocity m/s
v = [1:2:22];

% drag force N
F_d = 0.5 * c_d * a * rho * v.^2;

%plot drag force vs velocity
plot(v, F_d)
ylabel('drag force')
xlabel('velocity')

Curve obtained is parabolic in nature.

Note: In this case, the drag coefficient is kept constant.

If the drag coefficient is changing from 0.1 to 1.1 at the increment of 0.1.

And remaining all parameters remain unchanged.

Then,

% program for calculating the drag force on the bicycle
close all
clear all
clc

% Input
%drag_coefficient
c_d = [0.1:0.1:1.1]';

%area m^2
a = 0.5;

%density kg/m^3
rho = 1.225;

% velocity m/s
v = [1:2:11];

% drag force N
F_d = 0.5 * c_d * a * rho * v.^2;

%plot drag force vs velocity
plot(v, F_d)
ylabel('drag force')
xlabel('velocity')

As seen from the curve as the value of the drag coefficient increases, the drag force also increases.

• The plot of drag force vs drag coefficient

Shape	Drag Coefficient
Flat plate	1.28
Prism	1.14
Bullet	0.295
Airfoil	0.045

These values are taken from the internet.

These values are for the same front area.

In this velocity is increasing from 10m/s to 22m/s at rate of 5 m/s

a = 0.5m^2

density of air = 1.225kg/m^3

% program for calculating the drag force on the bicycle
close all
clear all
clc

% Input
%drag_coefficient for airfoil = 0.045
%drag coefficient for bullet = 0.295
%drag coefficient for prism = 1.14
%drag coefficient for flat plat = 1.28

c_d =  [ 0.045 0.295 1.14 1.28 ];

%area m^2
a = 0.5;

%density kg/m^3
rho = 1.225;

% velocity m/s
v = [ 10:5:25 ]; 

% drag force N
F_d = 0.5 * rho * a * c_d .*  v .* v 


%plot drag force vs velocity
plot(v, F_d, 'red' )
ylabel('drag force')
xlabel('drag coefficient')