[CfdIntro]

I have this piece of code which calculates the coordinates of a point(qx,qy) after it is rotated around an origin(ox, oy) by an angle(angle):

import math  

def rotate(origin, point, angle): 
  
ox, oy = origin 
px, py = point  

qx = ox + math.cos(angle) * (px - ox) - math.sin(angle) * (py - oy) 
qy = oy + math.sin(angle) * (px - ox) + math.cos(angle) * (py - oy) 

return qx, qy  

print(rotate((ox, oy), (px, py), math.radians(angle)))

I want to get the coordinates of an airfoil at different angle of attacks. For this, I want the final script to be able to read the x,y coordinates of the airfoil at 0 degrees angle of attack from a .txt file, do the calculation for all the coordinates for a new angle of attack and then export the results to a new .geo file.

I have this code that lets the script to open the .txt file with the coordinates at 0 angle of attack:

coordsAt0 = [] 
with open('coordinatesAt0.txt') as fin: 

fin.readline() 

for l in fin:     

coords = map(float,l.split())     

coordsAt0.append(coords[:2])

After the calculation of the coordinates for the new angle of attack, I have this code which exports the new coordinates to a new .geo file.

with open('newcoordinates.geo','w') as fout:

for i, c in enumerate(coordsAt0):

fout.write('Point (%i) = {%f, %f, 0, 1};\n'%(i+1,c[0],c[1]))

My problem is how should I implement the code that calculates the new coordinates of the airfoil at a new angle of attack?

Any hint or a simpler piece of code on how to do it would be greatly appreciated!

Regards,
CfdIntro

[Flowkersma]

Hi,

Looks like a familiar piece of code :-)

After line

coords = map(float,l.split())

You can just add the rotate function call

angle = 10 # degrees
origin = (0,0)
coords0 = rotate(coords[:2], origin, math.radians(angle))
coordsAt0.append(coords0)

Regards, Mikko

[CfdIntro]

Originally Posted by Flowkersma

Hi,

Looks like a familiar piece of code :-)

After line

coords = map(float,l.split())

You can just add the rotate function call

angle = 10 # degrees
origin = (0,0)
coords0 = rotate(coords[:2], origin, math.radians(angle))
coordsAt0.append(coords0)

Regards, Mikko

Hi,

I was trying to have the script open the .txt file with the coordinates at 0 AoA, rotate the coordinates by the desired AoA, print the results into a new .txt file, then read the coordinates at the new AoA and finally export the results into a .geo format file. That being said, your suggestion saved me about 30 lines of code!

Thanks again for the tip

Regards,
CfdIntro