- #1

super sky

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I'm trying to plot the pressure distribution around a cylinder in a uniform flow field, so that the graphic is a circle with the pressure curve around it, like in the image below.

http://img843.imageshack.us/img843/4649/63792687.th.jpg [Broken]

Uploaded with ImageShack.us

I have the equation for the ideal pressure coefficient Cp (which is what I'm wanting to display), and t is the theta values. (See code below)

Then I use the polar function to plot it... polar(t,Cp)... but that starts at the origin, which isn't what I want. I thought it might help if I added the radius of my proposed circle to Cp, but it doesn't. So maybe I need a scaling factor on Cp or something..?

Could someone help me out?

Thanks.

http://img843.imageshack.us/img843/4649/63792687.th.jpg [Broken]

Uploaded with ImageShack.us

I have the equation for the ideal pressure coefficient Cp (which is what I'm wanting to display), and t is the theta values. (See code below)

Then I use the polar function to plot it... polar(t,Cp)... but that starts at the origin, which isn't what I want. I thought it might help if I added the radius of my proposed circle to Cp, but it doesn't. So maybe I need a scaling factor on Cp or something..?

Could someone help me out?

Thanks.

Code:

```
%%% Flow Around a Cylinder %%%
% Initialise variables
clear all
clc
U = 12; % Freestream velocity m/s
M = 2; % Doublet strength
radius = sqrt(M/2/pi/U); % Cylinder radius
t = linspace(0,2*pi,50); % Range of theta values
circle = ones(1,50); % Create vector
circle = radius.*circle; % Circle of required radius
% Calculations
cp = 1 - 4.*(sin(t)).^2; % Pressure coefficient
cp_scaled = cp + radius; % Attempted scaling
% Display graphs
polar(t,cp,'--r')
hold on
polar(t,circle)
hold off
figure
polar(t,cp_scaled,'--r')
hold on
polar(t,circle)
hold off
```

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