def load_force_coefficients(filepath, config):
"""Load forces from file and return force coefficients."""
# Load forces from file.
t, fx, fy, fz = petibmpy.read_forces(filepath)
fx *= -1.0 # drag to thrust
# Convert forces to force coefficients.
rho, U_inf, A_plan = (getattr(config, name)
for name in ('rho', 'U_inf', 'A_plan'))
coeff = 1 / (0.5 * rho * U_inf**2 * A_plan)
# Non-dimensionalize time values by period.
t /= config.T
ct, cl, cz = petibmpy.get_force_coefficients(fx, fy, fz, coeff=coeff)
return Solution(t=t, ct=ct, cl=cl, cz=cz)
def test_get_force_coefficients(self):
"""Test function `get_force_coefficients`."""
dim = 3
# Load forces from file.
filepath = self.datadir / f'forces{dim}d-single-0.txt'
_, fx, fy, fz = petibmpy.read_forces(filepath)
# Convert one direction with unit coefficient.
cd, = petibmpy.get_force_coefficients(fx)
self.assertTrue(numpy.allclose(cd, fx))
# Convert two directions with unit coefficient.
cd, cl = petibmpy.get_force_coefficients(fx, fy)
self.assertTrue(numpy.allclose(cd, fx))
self.assertTrue(numpy.allclose(cl, fy))
# Convert three directions with unit coefficient.
cd, cl, cz = petibmpy.get_force_coefficients(fx, fy, fz)
self.assertTrue(numpy.allclose(cd, fx))
self.assertTrue(numpy.allclose(cl, fy))
self.assertTrue(numpy.allclose(cz, fz))
# Convert three directions with random coefficient.
coeff = random.uniform(0.1, 5.0)
cd, cl, cz = petibmpy.get_force_coefficients(fx, fy, fz, coeff=coeff)
self.assertTrue(numpy.allclose(cd / coeff, fx))
self.assertTrue(numpy.allclose(cl / coeff, fy))
self.assertTrue(numpy.allclose(cz / coeff, fz))
import pathlib
from matplotlib import pyplot
import petibmpy
simudir = pathlib.Path(__file__).absolute().parents[1]
filepath = simudir / 'output' / 'forces-0.txt'
t, fx, fy, fz = petibmpy.read_forces(filepath)
rho, u_inf = 1.0, 1.0 # density and freestream speed
dyn_pressure = 0.5 * rho * u_inf**2 # dynamic pressure
c = 1.0 # chord length
Lz = 3.2 * c # spanwise length
coeff = 1 / (dyn_pressure * c * Lz) # scaling factor for force coefficients
cd, cl, cz = petibmpy.get_force_coefficients(fx, fy, fz, coeff=coeff)
pyplot.rc('font', family='serif', size=16)
fig, ax = pyplot.subplots(figsize=(8.0, 4.0))
ax.set_xlabel('Non-dimensional time')
ax.set_ylabel('Force coefficients')
ax.grid()
ax.plot(t, cd, label='$C_D$')
ax.plot(t, cl, label='$C_L$')
ax.plot(t, cz, label='$C_z$')
ax.legend()
ax.set_xlim(t[0], t[-1])
ax.set_ylim(-0.1, 3.0)
fig.tight_layout()
figdir = simudir / 'figures'
# Create the wing kinematics.
wing = rodney.WingKinematics(Re=200.0, St=0.6, psi=110.0, nt_period=2000)
# Compute the cycle-averaged thrust.
filepath = datadir / 'forces-0.txt'
t, fx, _, _ = petibmpy.read_forces(filepath)
thrust = -fx # switch from drag to thrust
time_limits = (4 * wing.T, 5 * wing.T) # interval to consider for average
thrust_avg, = petibmpy.get_time_averaged_values(t, thrust, limits=time_limits)
# Compute the cycle-averaged thrust coefficient.
rho, U_inf, A_plan = (getattr(wing, name)
for name in ('rho', 'U_inf', 'A_plan'))
scale = 1 / (0.5 * rho * U_inf**2 * A_plan)
ct, = petibmpy.get_force_coefficients(thrust, coeff=scale)
ct_avg, = petibmpy.get_time_averaged_values(t, ct, limits=time_limits)
# Load original boundary coordinates from file.
filepath = simudir / 'wing.body'
wing.load_body(filepath, skiprows=1)
# Compute surface area associated with each Lagrangian marker.
ds = wing.A_plan / wing.size
# Create virtual boundary around flat plate.
# The flat surface is extended by d grid cells on lower and upper surfaces.
d = 0.03 * wing.c # normal distance from original markers (3% chord length)
x0, y0, z0 = wing.get_coordinates()
xv0 = numpy.tile(x0, 2)
yv0 = numpy.concatenate((y0 - d, y0 + d))
"""Generate a figure of the drag and lift force coefficients over time.
Save the figure in the sub-folder `figures` of the simulation directory.
"""
import sys
import pathlib
from matplotlib import pyplot
import petibmpy
simudir = pathlib.Path(__file__).absolute().parents[1]
filepath = simudir / 'output' / 'forces-0.txt'
t, fx, fy = petibmpy.read_forces(filepath)
cd, cl = petibmpy.get_force_coefficients(fx, fy, coeff=2.0)
pyplot.rc('font', family='serif', size=16)
fig, ax = pyplot.subplots(figsize=(8.0, 4.0))
ax.set_xlabel('Non-dimensional time')
ax.set_ylabel('Force coefficients')
ax.grid()
ax.plot(t, cd, label='$C_D$')
ax.plot(t, cl, label='$C_L$')
ax.legend(ncol=2)
ax.set_xlim(t[0], t[-1])
ax.set_ylim(0.0, 3.0)
fig.tight_layout()
figdir = simudir / 'figures'
figdir.mkdir(parents=True, exist_ok=True)