def test_rotate2d(self):
"""Test function `rotate2d`."""
x, y = petibmpy.rotate2d(self.x, self.y)
self.assertTrue(numpy.allclose(x, self.x))
self.assertTrue(numpy.allclose(y, self.y))
x, y = petibmpy.rotate2d(self.x, self.y, angle=360.0)
self.assertTrue(numpy.allclose(x, self.x))
self.assertTrue(numpy.allclose(y, self.y))
x, y = petibmpy.rotate2d(self.x,
self.y,
angle=2 * numpy.pi,
mode='rad')
self.assertTrue(numpy.allclose(x, self.x))
self.assertTrue(numpy.allclose(y, self.y))
with self.assertRaises(ValueError):
petibmpy.rotate2d(x, y, mode='typo')
def get_CD_CL(self, filepath, bodypath):
"""Load the forces from file and return the force coefficients."""
t, fx, fy = petibmpy.read_forces(filepath)
# Non-dimensionalize time by the period.
t_nodim = self.f * t
# Reverse sign of force in x-direction when the body moving
# in the positive x-direction.
U0, _ = self.translational_velocity(t)
fx *= -U0 / numpy.abs(U0)
# Normalize the forces by the maximum quasi-steady force on the wing.
D, L = [], []
x0 = petibmpy.read_body(bodypath, skiprows=1, usecols=0)
y0 = numpy.zeros_like(x0)
for ti in t:
alpha = self.orientation_angle(ti)
x, y = petibmpy.rotate2d(x0,
y0,
center=(0.0, 0.0),
angle=alpha,
mode='rad')
Di, Li = self.quasi_steady_forces(ti, x, y, 0.0, 0.0, rho=1.0)
D.append(numpy.max(Di))
L.append(numpy.max(Li))
D, L = numpy.array(D), numpy.array(L)
cd, cl = fx / numpy.max(D), fy / numpy.max(L)
return {'CD': (t_nodim, cd), 'CL': (t_nodim, cl)}
def position(self, t, x0, y0):
"""Return the coordinates of the wing a given time t."""
xd, yd = self.displacement(t)
alpha = self.orientation_angle(t)
x, y = x0 + xd, y0 + yd
x, y = petibmpy.rotate2d(x,
y,
center=(xd, yd),
angle=alpha,
mode='rad')
return x, y
"""Generate the coordinates of the snake boundary."""
import sys
import pathlib
import numpy
from matplotlib import pyplot
import petibmpy
# Read the original coordinates of the section.
rootdir = pathlib.Path(__file__).absolute().parents[1]
datadir = rootdir / 'data'
filepath = datadir / 'snake2d.body'
with open(filepath, 'r') as infile:
x, y = numpy.loadtxt(infile, dtype=numpy.float64, skiprows=1, unpack=True)
# Apply rotation and regularize the geometry to desired resolution.
x, y = petibmpy.rotate2d(x, y, center=(0.0, 0.0), angle=-35.0)
x, y = petibmpy.regularize2d(x, y, ds=0.004)
# Write new coordinates in file located in simulation directory.
filepath = rootdir / 'snake2d35.body'
with open(filepath, 'w') as outfile:
outfile.write(f'{x.size}\n')
with open(filepath, 'ab') as outfile:
numpy.savetxt(outfile, numpy.c_[x, y])