Flow over Bi-cycle

% program to calculate  drag force for a bicycle
clear all 
close all 
clc 

%drag force with variable velocity
%inputs 
% drag coefficient
c_d= 0.8;
% frontal area  
area=0.5;
% density of air 
density=1.225;
% velocity of cyclist 
velocity= 1:50;

%formula 
drag_force= density*area*velocity.*velocity*c_d*0.5;  

%plot to generate velocity vs drag force 
figure(1)
plot(velocity,drag_force)
xlabel('velocity')
ylabel('drag_force')
grid on 


%program to calculate drag force with variable drag co efficient
% drag coefficient
c= [0.04 0.09 0.42 0.47 0.5 0.8 0.82 1.05 1.15 1.28];
% frontal area 
a=0.5;
% density of air 
d=1.225;
% velocity of cyclist 
v=15;

% formula 
d_f= d*a*v^2*c*0.5;

%plot to generate drag force vs drag co efficient
figure(2)
plot(c,d_f)
xlabel('drag_coefficient')
ylabel('drag_force')
grid on 

Figure (1) generates a plot between varying velocity vs drag force calculated. The plot is shown below

Figure (2) generates a plot between varying drag co efficient vs drag force calculated. The plot is shown below

In the code snippet, all the inputs which depends on the drag force is defined initially. The drag force is calculated using the formula given in the snippet and a graph of velocity vs drag force and drag co efficient vs drag force is plotted.

It is observed that the drag force depends on

1. Density of the fluid in which the experiment is conducted. In this case, it is air.

2. Frontal area which is affected by the fluid.

3. Velocity in which the cycle is moving.

4. Drag co_efficient ( it is the fluid resistence which creates a pressure difference).

It is seen that velocity is the most important component as there drag force varies with velocity^2. hence the plot generated is parabolic.

This shows that as velocity of the cycle increases drag forces also increases. Drag co efficient is measured experimentally and drag co efficient depends reynold's number. The plot generated in figure (2) is a straight line and drag force varies linearly with drag co efficient.

If drag co efficient is less, drag force is also less. Hence aerofoil has very less drag co efficient and frontal area.