flow rate calculation in the microfluidic channels using data obtained from PIV using the Purday approximation.

```%Program uses the maximum velocity obtained from PIV to calculate the flow
%rate
%Define time step (us)
time step=90;

%Channel width (um)
w=1500;
%Channel height (um)
h=212.5;
%For each time step/file:
%Access the x-component of velocity data, vx and find the maximum velocity
%Average the velocity data along each column to represent a global average
%for the divided pixel down the image window. Store in an array
maximum velocity=zeros(1,numel(v));
for i = 1 : numel(v)
%Average each column and store in a row each
average velocity along y=mean(v(i).vx,1);
%account for negatives (oscillatory flow)
avg=mean(average velocity along y);
if avg¿0
maximum velocity(i)=max(average velocity along y);
else
maximum velocity(i)=min(average velocity along y);
end
end
%Comes out currently in units of pixels
%Multiply by pixel to micron scaling factor for 10x magnification lens.
%Number of microns/pixels
pixel to micron=550/839.75;
%So now in units of microns
maximum velocity=maximum velocity*pixel to micron;
%Convert to m
maximum velocity=maximum velocity*10ˆ-6;

%Divide by time step to get velocity in m/s
maximum velocity=maximum velocity/(time step*10ˆ-6);
%Calculate channel area (in mˆ2)
A=w*h*(10ˆ-6)ˆ2;
%Calculate flow rate through Purday Approximation - Calculate n and m as
%well
alpha=h/w;
%Calculate n
if alpha ¿= (1/3);
n=2+0.3*(alpha-(1/3));
else
n=2;
end
%Calculate m
m=1.7+0.5*alphaˆ-1.4;
%Flow rate in mˆ3/s
Q=(m/(m+1))*(n/(n+1))*A*maximum velocity;
%Convert to ml/min
Q=Q*60*10ˆ3*10ˆ3;```