Week 1 - Flow over Bicycle

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MATLAB CODE:

 %flow_over_bicycle close all  clear all  clc %inputs  %Density kg/m^3   Rho=1.2;  %Area m^2   A=0.2;  %Drag Coefficient dimensionless    c_d=1.15;  %Velocity m/s   V=[0:40];  %to_find drag_force1 with different velocities Newtons   drag_force1=0.5*Rho*A*V.^2*c_d;     %coefficient of  drag   C_d=[0.04 0.09 0.42 0.47 0.82 1.15];   %velocity m/s   v=40;   %to find drag_force2 with different C_d values   drag_force2=0.5*Rho*A*v^2.*C_d;  plot(V,drag_force1,'color','r')  xlabel('velocity')  ylabel('drag force')  figure  plot(C_d,drag_force2)  xlabel('drag coefficient')  ylabel('drag force')

CODE SUMMARY:

• The challenge was to find the drag force of a cyclist with a certain drag coefficient, frontal area and density moving with different velocities. Also to find the drag force for objects of different shapes of same area value which have different drag coefficient values.
• We know that drag force=0.5*rho*A*v^2*cd
• So first the inputs were assigned i.e Density Rho=1.2kg/m^3 , Frontal Area A=0.2 m^2 , drag coefficient c_d=1.15 and velocities ranging from 0-40 m/s.
• The other inputs were for different coefficient of drag values were all density and frontal area parameters remained same whereas coefficient of drag and velocity was declared differently such C_d for various shapes are shown in figure. Velocity taken was 40 m/s.

• After this two drag forces were found separately refered as drag_force1 and drag_force2.
• The plots for Velocity vs drag force and drag coefficient vs drag force were plotted using the plot command. The plots are given below.

figure command was used to get seperate graphs for each of the following data.

ERRORS FACED:

1. Mistakes were very common such as a typo which were thrown once. Solved it by verifying.

2.The plot were overwriting so i used the figure command to get 2 seperate plots.

3.Another erro i commited was taking both diiferent values velocity and drag coefficient in the same equation and multiplying it which gave me continous errors. So hence i realised to use 2 different drag forces and found it seperately and plotted it accordingly.

RESULT:

• From the velocity vs drag force plot we can see that drag force is propotional to square times the velocity hence the drag force increases as the velocity increases.
• From the drag coefficient vs drag force for different shapes its clear that the frontal area should be minimum to reduce the drag in an object.