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# Combining multiple velocity profiles into one graph?

Asked by Juhani on 29 Mar 2013

Ok so this is really a few questions in one. I have 3 data sets from an air jet experiment, showing the velocity profiles at 3 different axial distances from a nozzle: http://oi47.tinypic.com/2uh3502.jpg

I want to replot these graphs as parallel vector fields and place them all on one graph, with an end result something like this: http://herkules.oulu.fi/isbn9514259777/html/graphic8484.png, where the y-axis would be radial distance from the nozzle centreline, the x-axis would be axial distance from the nozzle and the length of the vectors would be the velocity of the air at that point. How do I do this?

I've tried using the feather function to come up with a vector profile, but the best I could do was this: http://oi49.tinypic.com/351h6k8.jpg which is obviously not what I want.

Any ideas?

proecsm on 29 Mar 2013

can you post some of your data?

Juhani on 29 Mar 2013

Sure, here is my data:

R60=[-28:4:28];

R180=[-50:5:50];

R300=[-60:5:60];

V60=[2.19 3.79 8.00 13.15 16.64 16.97 17.11 17.25 17.34 17.25 13.27 8.00 3.58 1.79 0];

V180=[0 1.79 2.83 4.38 5.66 7.48 9.55 11.87 13.74 14.91 14.97 13.97 11.66 9.12 6.57 4.2 2.53 0 0 0 0];

V300=[0 1.79 2.53 3.35 4.38 5.06 5.8 6.93 8.1 9.03 9.88 10.35 10.51 10.04 9.3 8 7.04 5.66 4.73 4 3.35 2.53 1.26 0 0 ];

'R' represents the radial distance from the centreline, and 'V' is the velocity. The numbers represent the axial distance from the nozzle. So for example R60 and V60 are 60mm from the nozzle. Obviously R60 and V60 have to go together, etc.

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Answer by Sean de Wolski on 29 Mar 2013
Edited by Sean de Wolski on 29 Mar 2013

I didn't see the images. Use feather() or quiver()

For example:

```quiver(60*ones(size(V60)),R60,V60,zeros(size(V60)))
```

Also, this is probably a worthy read:

Juhani on 30 Mar 2013

That's great thanks. How do I combine this and the other two into one plot? Sorry if this is obvious but I'm still a complete novice to matlab!

Sean de Wolski on 1 Apr 2013

Use hold on and call the above three times:

```doc hold
```