 # Beginner and plotting CFD data from file

I'm a CFD student and I wish to learn to make high-quality plots from my
calculations using matplotlib. However, I'm a complete novice in using
matplotlib and python and I didn't find any earlier posts so here goes.

I have data form Ansys Fluent in the following form
continuity x-velocity y-velocity energy
k epsilon
1 0.00011115784 1.5359586e-07 1.0506172e-07 0.0032920227
0.40809903
1 0.16584706 0.0047719572 2.7355736e-07
0.026478255 0.19814095
0.5674 0.044237841 0.0026294924 2.8202695e-07 0.030139321
0.13935529

The first line is for the first iteration, the second line for the second
iteration etc. Basically, I would like to have plot this data and have a
picture like http://openfoamwiki.net/images/f/ff/Pump_residuals.png this

Any help would be much appreciated.

BR Jack

···

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Jack,

First, you would load your data using numpy’s loadtxt() function. You can tell loadtxt() to skip the first line since it is a header. This will give you a 2-D array (n rows and 6 columns) where n is the number of iterations.

You can then plot the data using matplotlib’s plot command (or semilogy to automatically get y-log scaling), passing in the first column for the x data, and then the other columns for the y data.

So, your code would look something like this:

import numpy as np
import matplotlib.pyplot as plt

plt.semilogy(data[:, 0], data[:, 1:])
plt.xlabel(‘Iteration’)
plt.ylabel(‘Residuals’)

plt.legend([‘Ux_0’, ‘Uy_0’, ‘p_0’, ‘k_0’, ‘epsilon_0’])
plt.show()

That should get you a similar plot. There are more things you can do to control various aspects, but this should get you a good start.

I hope this helps!
Ben Root

···

On Tue, Jan 18, 2011 at 5:33 PM, sgee <jaakko.laa@…287…> wrote:

I’m a CFD student and I wish to learn to make high-quality plots from my

calculations using matplotlib. However, I’m a complete novice in using

matplotlib and python and I didn’t find any earlier posts so here goes.

I have data form Ansys Fluent in the following form

continuity x-velocity y-velocity energy

k epsilon

1 0.00011115784 1.5359586e-07 1.0506172e-07 0.0032920227

0.40809903

1 0.16584706 0.0047719572 2.7355736e-07

0.026478255 0.19814095

0.5674 0.044237841 0.0026294924 2.8202695e-07 0.030139321

0.13935529

The first line is for the first iteration, the second line for the second

iteration etc. Basically, I would like to have plot this data and have a

picture like http://openfoamwiki.net/images/f/ff/Pump_residuals.png this

Any help would be much appreciated.

BR Jack

Ben,