[CapSizer]

The wall forces calculation method in the recent versions of OF work very nicely, but produce a file (by default called forces.dat) with a lot of brackets (or parentheses, if you speak that variant of English). A typical line in the file looks like this:


(((6.57 128.05 364.35) (34.46 2.43 4.29)) (( etc .....) (......) (......)))


Now I really like to plot the force history as a means of judging convergence, but this format is not amenable to easy plotting with Gnuplot. One can obviously import into a spreadsheet, but that is mighty tedious. The question is this: Is there an easy way of telling Gnuplot to ignore the brackets, or is there another plotting program that can do it easily? I'm sure that one can give Gnuplot a "plot using " command that can deal with the format .... I just don't seem to get it right! Any advice?

[rieuk]

I plotted my stuff in Excel but only after I'd extracted and compiled all the data into one tab delimited file using a bash script. It's not too difficult. A few hours reading of bash scripting if you have no experience should be good enough.

[sinusmontis]

Hello,

you could use "sed" to filter your gunplot input. Use following line in gnuplot (the input for gnuplot will be the output of sed):

plot "< sed s/[\\(\\)]//g input.dat" using 1:2


Regards,

Malte

[CapSizer]

Great, thanks for that, it has got me going along the right lines!

[egp]

Another solution is to use python to parse and plot, e.g.,

import re
forceRegex=r"([0-9.Ee\-+]+)\s+\(+([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\)\s\(([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9
.Ee\-+]+)\)+\s\(+([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\)\s\(([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\)
+"
t = []
fpx = []; fpy = []; fpz = []
fvx = []; fvy = []; fvz = []
mpx = []; mpy = []; mpz = []
mvx = []; mvy = []; mvz = []
pipefile=open('forces.dat','r')
lines = pipefile.readlines()
for line in lines:
        match=re.search(forceRegex,line)
                if match:
                        t.append(float(match.group(1)))
                        fpx.append(float(match.group(2)))
                        fpy.append(float(match.group(3)))
                        fpz.append(float(match.group(4)))
                        fvx.append(float(match.group(5)))
                        fvy.append(float(match.group(6)))
                        fvz.append(float(match.group(7)))
                        mpx.append(float(match.group(8)))
                        mpy.append(float(match.group(9)))
                        mpz.append(float(match.group(10)))
                        mvx.append(float(match.group(11)))
                        mpy.append(float(match.group(12)))
                        mpz.append(float(match.group(13)))
xlabel('time (sec)')
ylabel('force (N)')
grid()
title('Example of using python to parse the force/moment tuples')
plot(t,fpx,'o-')

---

Of course, you need numpy and matplotlib loaded for the above example to work. I would also recommend using ipython as it permits an improved interactive environment.

If you haven't studied regular-expressions (regex), I would recommend the python regex howto and the book by H.P. Langtangen, "Python Scripting for Computational Science."

[protarius]

I found some typos in the python code. The corrected code should be:

#!/usr/bin/python

import pylab

import re
forceRegex=r"([0-9.Ee\-+]+)\s+\(+([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\)\s\(([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9 .Ee\-+]+)\)+\s\(+([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\)\s\(([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\)+"
t = []
fpx = []; fpy = []; fpz = []
fvx = []; fvy = []; fvz = []
mpx = []; mpy = []; mpz = []
mvx = []; mvy = []; mvz = []
pipefile=open('forces.dat','r')
lines = pipefile.readlines()
for line in lines:
        match=re.search(forceRegex,line)
        if match:
                t.append(float(match.group(1)))
                fpx.append(float(match.group(2)))
                fpy.append(float(match.group(3)))
                fpz.append(float(match.group(4)))
                fvx.append(float(match.group(5)))
                fvy.append(float(match.group(6)))
                fvz.append(float(match.group(7)))
                mpx.append(float(match.group(8)))
                mpy.append(float(match.group(9)))
                mpz.append(float(match.group(10)))
                mvx.append(float(match.group(11)))
                mvy.append(float(match.group(12)))
                mvz.append(float(match.group(13)))

pylab.xlabel('time (sec)')
pylab.ylabel('force (N)')
pylab.grid(True)
##title('Example of using python to parse the force/moment tuples')
pylab.plot(t,fpx,'o-')
pylab.show()

Regards

[jferrari]

Originally Posted by CapSizer

The wall forces calculation method in the recent versions of OF work very nicely, but produce a file (by default called forces.dat) with a lot of brackets (or parentheses, if you speak that variant of English). A typical line in the file looks like this:


(((6.57 128.05 364.35) (34.46 2.43 4.29)) (( etc .....) (......) (......)))


Now I really like to plot the force history as a means of judging convergence, but this format is not amenable to easy plotting with Gnuplot. One can obviously import into a spreadsheet, but that is mighty tedious. The question is this: Is there an easy way of telling Gnuplot to ignore the brackets, or is there another plotting program that can do it easily? I'm sure that one can give Gnuplot a "plot using " command that can deal with the format .... I just don't seem to get it right! Any advice?

If you're able to get the forces.dat file you should also be able to get the force coefficients. The forceCoeffs.dat file is formatted differently and is easier to use gnuplot to check the convergence.

[hewei]

Thank you very much Malte!! you freed me from huge excel working,
is there some command to read the last row data in one column? because I want to plot the residuals vs time. like
plot 'file.dat' using 1$2-last_data_in_column_2), or write command "value=last_data_in_column_2, file.dat"
in a script file?
every time I have to write "last_data_in_column_2" by hand, this is really boring.
thanks you again.
Wei

Originally Posted by sinusmontis

Hello,

you could use "sed" to filter your gunplot input. Use following line in gnuplot (the input for gnuplot will be the output of sed):

plot "< sed s/[\\(\\)]//g input.dat" using 1:2


Regards,

Malte

[isabel]

Dear everybody,

I need to represent pressure and viscous forces using gnuplot. This is my forces.dat file:

# CofR : (0 0 0)
# Time forces(pressure,viscous,porous) moment(pressure,viscous,porous)
1 ((824.789 2197.69 5.61904e-13),(0.00474683 0.000806522 -8.08238e-18),(0 0 0)) ((-54.9423 20.6197 -3230.49),(-2.01631e-05 0.000118671 -0.00011563),(0 0 0))
2 ((570.161 1591.88 4.32564e-13),(0.0134802 0.00160194 2.91544e-18),(0 0 0)) ((-39.797 14.254 -3401.42),(-4.00486e-05 0.000337004 0.0229561),(0 0 0))
3 ((-70.8628 -24.5796 5.61076e-14),(0.0221518 0.0019545 2.31609e-18),(0 0 0)) ((0.61449 -1.77157 -2873.97),(-4.88625e-05 0.000553795 0.0440349),(0 0 0))
4 ((-436.165 -814.382 -2.1011e-13),(0.0287956 0.00371196 -3.41893e-18),(0 0 0)) ((20.3595 -10.9041 -1779.13),(-9.27991e-05 0.00071989 0.0575702),(0 0 0))
5 ((-337.19 -416.93 -2.2233e-13),(0.0389092 0.00995635 -2.12376e-17),(0 0 0)) ((10.4233 -8.42976 -445.623),(-0.000248909 0.00097273 0.073619),(0 0 0))

.... etcetera (many lines)


In order to plot this, I type:

plot "./postProcessing/forces/0/forces.dat" using 1:3 with lines title "pressure",\
"./postProcessing/forces/0/forces.dat" using 1:4 with lines title "viscous"


And I have this error:

plot "./postProcessing/forces/0/forces.dat" using 1:2 with lines title "pressure", "./postProcessing/forces/0/forces.dat" using 1:3 with lines title "viscous"
"forces", line 10: warning: Skipping data file with no valid points


Nevertheless, if I try using columns 1:3 and 1:4 everything is fine, ¿is pressure force column 3 and viscous force column 4 or am I wrong?

[balkrishna]

Hi Protarius,

The regexp gives empty arrays for my forces.dat file. Is there anyone where I can understand the breakup of the pattern.

Thanks,
Balkrishna.

[balkrishna]

With the way the forces.dat is outputted currently the following code works perfectly for me.

#!/usr/bin/python                                                                                                                                                                                                                     
import pylab

import re

#Current Input
#1.000000e+00    ((1.460676e+04 -1.948520e+02 9.535164e+02) (2.508036e-02 -6.720399e-05 -3.082446e-04) (0.000000e+00 0.000000e+00 0.000000e+00)) ((1.140514e+04 1.153182e+05 -1.730316e+05) (-3.153913e-03 1.658614e-01 -2.916495e-01\
) (0.000000e+00 0.000000e+00 0.000000e+00)                                                                                                                                                                                            

forceRegex=r"([0-9.Ee\-+]+)\s+\(+([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)+\)+\s+\(+([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)+\)+\s+\(+([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)+\)+\s+\(+([0-9.Ee\-+]+)\s([0-9.Ee\-+]\
+)\s([0-9.Ee\-+]+)+\)+\s+\(+([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)+\)+\s+\(+([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)\s([0-9.Ee\-+]+)+\)"


t = []
fpx = []; fpy = []; fpz = []; #Pressure                                                                                                                                                                                               
fvx = []; fvy = []; fvz = []; #Viscous                                                                                                                                                                                                
fpox = []; fpoy = []; fpoz=[];#Porous                                                                                                                                                                                                 
mpx = []; mpy = []; mpz = []; #Moment Pressure                                                                                                                                                                                        
mvx = []; mvy = []; mvz = []; #Moment Viscous                                                                                                                                                                                         
mpox= []; mpoy = [];mpoz = [];#Moment Porous                                                                                                                                                                                          

pipefile=open('forces.dat','r')

lines = pipefile.readlines()

lth=len(lines);print(lth)

for line in lines:

        match=re.search(forceRegex,line)

        if match:
                t.append(float(match.group(1)))
                fpx.append(float(match.group(2)))
                fpy.append(float(match.group(3)))
                fpz.append(float(match.group(4)))
                fvx.append(float(match.group(5)))
                fvy.append(float(match.group(6)))
                fvz.append(float(match.group(7)))
                fpox.append(float(match.group(8)))
                fpoy.append(float(match.group(9)))
                fpoz.append(float(match.group(10)))
                mpx.append(float(match.group(11)))
                mpy.append(float(match.group(12)))
                mpz.append(float(match.group(13)))
                mvx.append(float(match.group(14)))
                mvy.append(float(match.group(15)))
                mvz.append(float(match.group(16)))
                mpox.append(float(match.group(17)))
                mpoy.append(float(match.group(18)))
                mpoz.append(float(match.group(19)))




pylab.xlabel('time (sec)')
pylab.ylabel('force (N)')
pylab.grid(True)

#title('Example of using python to parse the force/moment tuples')                                                                                                                                                                    

pylab.plot(t,fpx,'o-')
pylab.show()

[stephie]

Helle everyone,

first thank you for the skripts! For me the skript of Gabriele worked wonderful thank you so much!

I have small question - in OF I have a deep of 1cm in real it should be 20cm how can I scale the values of forces.dat according to the real deep? Might anyone please give my a hint how I have to modify the python script? I would be very grateful, cos I have no experience with python.

Thank you and best regads,
Stephie

[Carno]

Just wondering the sign convention in the forces.dat file.
Example: Does +ve sign for moment mean, it is generating moment and vice versa?
That means turbines rotor walls patch will have always +ve moments and compressors will have negative moment?
Or counterclockwise is positive?
Because my fan blades have +ve moment on the relevant axis.

[Deltapilot]

Thanks for the hint of using the sed filter in Gnuplot, it works fine!!

[ddcampayo]

Originally Posted by balkrishna

With the way the forces.dat is outputted currently the following code works perfectly for me...

Funny, that code works perfectly from within a jupyter notebook, but not as a script. It reads four lines (the header), then hangs :/

[kandelabr]

I wrote a few python scripts, if they are of any use to you:
https://damogranlabs.com/2018/09/ope...ing-shortcuts/

[bjnieuwboer]

I was also interested in plotting the forces and came to this tread. For me the method of @balkrishna did not work. It hangs as was mentioned earlier.

I found the work Pete Bechant on github https://gist.github.com/petebachant/6334510 .This was clearly based on this tread, but also did not work for me. However, it was a nice starting point. I distilled the different parts from the code and made a different working regular expression:

import matplotlib.pyplot as plt
import re
import numpy as np

# make regular expressions
scalarStr = r"([0-9.eE\-+]+)"
vectorStr = r"\(([0-9.eE\-+]+)\s([0-9.eE\-+]+)\s([0-9.eE\-+]+)\)"
space =  r"\s+"
threeVectorStr = r"\({}{}{}{}{}\)".format(vectorStr,space,vectorStr,space,vectorStr)
forceRegex = r"{}{}{}{}{}".format(scalarStr,space,threeVectorStr,space,threeVectorStr)

t = []
fpx = []; fpy = []; fpz = []
fpox = []; fpoy = []; fpoz = []
fvx = []; fvy = []; fvz = []
mpx = []; mpy = []; mpz = []
mpox = []; mpoy = []; mpoz = []
mvx = []; mvy = []; mvz = []

pipefile = open('./forces.dat','r')
lines = pipefile.readlines()

for line in lines:
        match = re.search(forceRegex,line)
        if match:
                t.append(float(match.group(1)))
                fpx.append(float(match.group(2)))
                fpy.append(float(match.group(3)))
                fpz.append(float(match.group(4)))
                fvx.append(float(match.group(5)))
                fvy.append(float(match.group(6)))
                fvz.append(float(match.group(7)))
                fpox.append(float(match.group(8)))
                fpoy.append(float(match.group(9)))
                fpoz.append(float(match.group(10)))
                mpx.append(float(match.group(11)))
                mpy.append(float(match.group(12)))
                mpz.append(float(match.group(13)))
                mvx.append(float(match.group(14)))
                mvy.append(float(match.group(15)))
                mvz.append(float(match.group(16)))
                mpox.append(float(match.group(17)))
                mpoy.append(float(match.group(18)))
                mpoz.append(float(match.group(19)))

plt.plot(t,fpz)