def test_updating_particle_arrays(self):
# Given
xd = [0.5]
hd = self.src.h[:1]
dest = get_particle_array(name='dest', x=xd, h=hd)
sph_eval = SPHEvaluator([dest, self.src],
equations=self.equations,
dim=1)
sph_eval.evaluate()
rho0 = dest.rho[0]
# When.
dest.x[0] = 0.0
sph_eval.update_particle_arrays([dest, self.src])
sph_eval.evaluate()
# Then.
self.assertNotEqual(rho0, dest.rho[0])
self.assertAlmostEqual(dest.rho[0], 7.0, places=1)
def _plot_cd_vs_t(self):
from pysph.solver.utils import iter_output, load
from pysph.tools.sph_evaluator import SPHEvaluator
from pysph.sph.equation import Group
from pysph.sph.wc.transport_velocity import (SetWallVelocity,
MomentumEquationPressureGradient, SolidWallNoSlipBC,
SolidWallPressureBC, VolumeSummation)
data = load(self.output_files[0])
solid = data['arrays']['solid']
fluid = data['arrays']['fluid']
x, y = solid.x.copy(), solid.y.copy()
cx = 0.5 * L; cy = 0.5 * H
inside = np.sqrt((x-cx)**2 + (y-cy)**2) <= a
dest = solid.extract_particles(inside.nonzero()[0])
# We use the same equations for this as the simulation, except that we
# do not include the acceleration terms as these are externally
# imposed. The goal of these is to find the force of the fluid on the
# cylinder, thus, gx=0.0 is used in the following.
equations = [
Group(
equations=[
VolumeSummation(
dest='fluid', sources=['fluid', 'solid']
),
VolumeSummation(
dest='solid', sources=['fluid', 'solid']
),
], real=False),
Group(
equations=[
SetWallVelocity(dest='solid', sources=['fluid']),
], real=False),
Group(
equations=[
SolidWallPressureBC(dest='solid', sources=['fluid'],
gx=0.0, b=1.0, rho0=rho0, p0=p0),
], real=False),
Group(
equations=[
# Pressure gradient terms
MomentumEquationPressureGradient(
dest='fluid', sources=['solid'], gx=0.0, pb=pb),
SolidWallNoSlipBC(
dest='fluid', sources=['solid'], nu=nu),
], real=True),
]
sph_eval = SPHEvaluator(
arrays=[dest, fluid], equations=equations, dim=2,
kernel=QuinticSpline(dim=2)
)
t, cd = [], []
for sd, fluid in iter_output(self.output_files, 'fluid'):
fluid.remove_property('vmag2')
t.append(sd['t'])
sph_eval.update_particle_arrays([dest, fluid])
sph_eval.evaluate()
Fx = np.sum(-fluid.au*fluid.m)
cd.append(Fx/(nu*rho0*Umax))
t, cd = list(map(np.asarray, (t, cd)))
# Now plot the results.
import matplotlib
matplotlib.use('Agg')
from matplotlib import pyplot as plt
f = plt.figure()
plt.plot(t, cd)
plt.xlabel('$t$'); plt.ylabel(r'$C_D$')
fig = os.path.join(self.output_dir, "cd_vs_t.png")
plt.savefig(fig, dpi=300)
plt.close()
return t, cd
def _plot_force_vs_t(self):
from pysph.solver.utils import iter_output, load
from pysph.tools.sph_evaluator import SPHEvaluator
from pysph.sph.equation import Group
from pysph.base.kernels import QuinticSpline
from pysph.sph.wc.transport_velocity import (
MomentumEquationPressureGradient, SummationDensity,
SetWallVelocity)
data = load(self.output_files[0])
solid = data['arrays']['solid']
fluid = data['arrays']['fluid']
prop = [
'awhat', 'auhat', 'avhat', 'wg', 'vg', 'ug', 'V', 'uf', 'vf', 'wf',
'wij', 'vmag', 'pavg', 'nnbr', 'auf', 'avf', 'awf'
]
for p in prop:
solid.add_property(p)
fluid.add_property(p)
# We find the force of the solid on the fluid and the opposite of that
# is the force on the solid. Note that the assumption is that the solid
# is far from the inlet and outlet so those are ignored.
print(self.nu, p0, self.dc, rho)
equations = [
Group(equations=[
SummationDensity(dest='fluid', sources=['fluid', 'solid']),
SummationDensity(dest='solid', sources=['fluid', 'solid']),
SetWallVelocity(dest='solid', sources=['fluid']),
],
real=False),
Group(
equations=[
# Pressure gradient terms
MomentumEquationPressureGradient(dest='solid',
sources=['fluid'],
pb=p0),
SolidWallNoSlipBCReverse(dest='solid',
sources=['fluid'],
nu=self.nu),
],
real=True),
]
sph_eval = SPHEvaluator(arrays=[solid, fluid],
equations=equations,
dim=2,
kernel=QuinticSpline(dim=2))
t, cd, cl = [], [], []
import gc
print(self.dc, self.dx, self.nu)
print('fxf', 'fxp', 'fyf', 'fyp', 'cd', 'cl', 't')
for sd, arrays in iter_output(self.output_files[:]):
fluid = arrays['fluid']
solid = arrays['solid']
for p in prop:
solid.add_property(p)
fluid.add_property(p)
t.append(sd['t'])
sph_eval.update_particle_arrays([solid, fluid])
sph_eval.evaluate()
fxp = sum(solid.m * solid.au)
fyp = sum(solid.m * solid.av)
fxf = sum(solid.m * solid.auf)
fyf = sum(solid.m * solid.avf)
fx = fxf + fxp
fy = fyf + fyp
cd.append(fx / (0.5 * rho * umax**2 * self.dc))
cl.append(fy / (0.5 * rho * umax**2 * self.dc))
print(fxf, fxp, fyf, fyp, cd[-1], cl[-1], t[-1])
gc.collect()
t, cd, cl = list(map(np.asarray, (t, cd, cl)))
# Now plot the results.
import matplotlib
matplotlib.use('Agg')
from matplotlib import pyplot as plt
plt.figure()
plt.plot(t, cd, label=r'$C_d$')
plt.plot(t, cl, label=r'$C_l$')
plt.xlabel(r'$t$')
plt.ylabel('cd/cl')
plt.legend()
plt.grid()
fig = os.path.join(self.output_dir, "force_vs_t.png")
plt.savefig(fig, dpi=300)
plt.close()
return t, cd, cl