FLOW OVER A BICYCLE USING MATLAB

Aim- To write a Matlab program to calculate drag force against a cyclist.

Governing Equations:-

Drag coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water. It is used in the drag quation in which a lower drag coefficient indicates the object will have less aerodynamic or hydrodynamic drag.

Drag force is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid.This can exist between two fluid layers (or surfaces) or a fluid and a solid surface.

Frontal Area physically represents the area as projected right along the velocity vector

(Drag Equation)

where:

is the drag force, which is by definition the force component in the direction of the flow velocity,

is the mass density of the fluid,^[7]

is the flow speed of the object relative to the fluid,

is the Frontal area.

I have written both the program in one program.

Program to plot Velocity vs Drag force and Drag Co-efficient vs Drag force.

clear all
close all
clc
%Inputs
close all
clc
%program to plot velocity vs Dragforce
%Inputs
%Drag_coefficient is constant
C_d1=0.8
%Area m^2
A1=0.1
%Density kg/m^3
rho1=1.2
%Velocity
V1=[1:12]
drag_force1=rho1*A1*V1.^2*C_d1*0.5;
%Drag coefficient for different shape of an object
%All objects have the same frontal area
%velocity is constant
C_d2=[0.045 0.5 0.295 1.14 1.28]  
%Area m^2
A2=0.1
%Density kg/m^3
rho2=1.2
% velocity
V2=2
drag_force2=V2.^2*C_d2*0.5*rho2*A2;
figure (1)
%subplot function is used here to plot two curves in one graph
subplot(2,1,1)
% To plot velocity vs Drag force 
plot(V1,drag_force1,'color','r')
ylabel('drag_force')
xlabel('Velocity')
% To provide title
title('Velocity vs Drag force')
subplot (2,1,2)
% To plot Drag coefficient vs Drag force
plot(C_d2,drag_force2,'linewidth',3,'color','b')
ylabel('Drag force')
xlabel('Drag coefficient')
title ('Drag coefficient vs Velocity')
grid on

Output-

Graph-