def test_bases(mu, case):
domain, vbasis, pbasis = case.domain, case.basis('v'), case.basis('p')
trfgeom = case.geometry(mu)
refgeom = case.refgeom
a_vbasis, a_pbasis = piola_bases(mu, case)
J = trfgeom.grad(case.geometry())
detJ = fn.determinant(J)
b_vbasis = fn.matmat(vbasis, J.transpose()) / detJ
b_pbasis = pbasis / detJ
Z = case.geometry(mu).grad(case.geometry())
detZ = fn.determinant(Z)
zdiff = np.sqrt(domain.integrate((Z - J)**2 * fn.J(refgeom), ischeme='gauss9').export('dense'))
np.testing.assert_almost_equal(zdiff, 0.0)
c_vbasis = fn.matmat(vbasis, Z.transpose()) / detZ
c_pbasis = pbasis
pdiff = np.sqrt(domain.integrate((a_pbasis - b_pbasis)**2 * fn.J(refgeom), ischeme='gauss9'))
np.testing.assert_almost_equal(pdiff, 0.0)
pdiff = domain.integrate((a_pbasis - c_pbasis)**2 * fn.J(refgeom), ischeme='gauss9')
np.testing.assert_almost_equal(pdiff, 0.0)
vdiff = np.sqrt(domain.integrate((a_vbasis - b_vbasis)**2 * fn.J(refgeom), ischeme='gauss9').export('dense'))
np.testing.assert_almost_equal(vdiff, 0.0)
vdiff = domain.integrate((a_vbasis - c_vbasis)**2 * fn.J(refgeom), ischeme='gauss9').export('dense')
np.testing.assert_almost_equal(vdiff, 0.0)
def splipy_to_nutils(spline):
""" Returns nutils domain and geometry object for spline mapping given by the argument """
from nutils import mesh, function
domain, geom = mesh.rectilinear(spline.knots())
cp = controlpoints(spline)
basis = domain.basis('spline', degree=degree(spline), knotmultiplicities=multiplicities(spline))
geom = function.matmat(basis, cp)
#TODO: add correct behaviour for rational and/or periodic geometries
return domain, geom
def basis(self, name, mu=None, transform=True):
func = super().basis(name, mu=mu)
if transform and f'{name}-trf' in self and mu is not None:
J = self[f'{name}-trf'](mu)
if J.ndim == 0:
func = func * J
else:
func = fn.matmat(func, J.transpose())
return func
def splipy_to_nutils(spline):
""" Returns nutils domain and geometry object for spline mapping given by the argument """
from nutils import mesh, function
domain, geom = mesh.rectilinear(spline.knots())
cp = controlpoints(spline)
basis = domain.basis('spline',
degree=degree(spline),
knotmultiplicities=multiplicities(spline))
geom = function.matmat(basis, cp)
#TODO: add correct behaviour for rational and/or periodic geometries
return domain, geom
def solution(self, lhs, field, mu=None, lift=True, J=None):
lhs = self.solution_vector(lhs, mu, lift)
if J is None:
func = self.basis(field, mu).dot(lhs)
else:
func = self.basis(field, mu, transform=False)
if J.ndim == 0:
func = func * J
else:
func = fn.matmat(func, J.transpose())
func = func.dot(lhs)
return self.domain.sample(*element.parse_legacy_ischeme(self.meta['vscheme'])).eval(func)
def project(self, projection):
ns = fn.Namespace()
for name, func in self._kwargs.items():
setattr(ns, name, func)
for p, (name, func) in zip(projection, self._defaults.items()):
if p is not None:
func = fn.matmat(p, func)
setattr(ns, name, func)
integrand = getattr(ns, self._evaluator)(self._code)
domain, geom, ischeme = self.prop('domain', 'geometry', 'ischeme')
with matrix.Numpy():
retval = domain.integrate(integrand * fn.J(geom), ischeme=ischeme)
return NumpyArrayIntegrand(retval)
def main(nelems:int, degree:int, reynolds:float, rotation:float, timestep:float, maxradius:float, seed:int, endtime:float):
'''
Flow around a cylinder.
.. arguments::
nelems [24]
Element size expressed in number of elements along the cylinder wall.
All elements have similar shape with approximately unit aspect ratio,
with elements away from the cylinder wall growing exponentially.
degree [3]
Polynomial degree for velocity space; the pressure space is one degree
less.
reynolds [1000]
Reynolds number, taking the cylinder radius as characteristic length.
rotation [0]
Cylinder rotation speed.
timestep [.04]
Time step
maxradius [25]
Target exterior radius; the actual domain size is subject to integer
multiples of the configured element size.
seed [0]
Random seed for small velocity noise in the intial condition.
endtime [inf]
Stopping time.
'''
elemangle = 2 * numpy.pi / nelems
melems = int(numpy.log(2*maxradius) / elemangle + .5)
treelog.info('creating {}x{} mesh, outer radius {:.2f}'.format(melems, nelems, .5*numpy.exp(elemangle*melems)))
domain, geom = mesh.rectilinear([melems, nelems], periodic=(1,))
domain = domain.withboundary(inner='left', outer='right')
ns = function.Namespace()
ns.uinf = 1, 0
ns.r = .5 * function.exp(elemangle * geom[0])
ns.Re = reynolds
ns.phi = geom[1] * elemangle # add small angle to break element symmetry
ns.x_i = 'r <cos(phi), sin(phi)>_i'
J = ns.x.grad(geom)
detJ = function.determinant(J)
ns.ubasis = function.matmat(function.vectorize([
domain.basis('spline', degree=(degree,degree-1), removedofs=((0,),None)),
domain.basis('spline', degree=(degree-1,degree))]), J.T) / detJ
ns.pbasis = domain.basis('spline', degree=degree-1) / detJ
ns.u_i = 'ubasis_ni ?u_n'
ns.p = 'pbasis_n ?p_n'
ns.sigma_ij = '(d(u_i, x_j) + d(u_j, x_i)) / Re - p δ_ij'
ns.N = 10 * degree / elemangle # Nitsche constant based on element size = elemangle/2
ns.nitsche_ni = '(N ubasis_ni - (d(ubasis_ni, x_j) + d(ubasis_nj, x_i)) n_j) / Re'
ns.rotation = rotation
ns.uwall_i = '0.5 rotation <-sin(phi), cos(phi)>_i'
inflow = domain.boundary['outer'].select(-ns.uinf.dotnorm(ns.x), ischeme='gauss1') # upstream half of the exterior boundary
sqr = inflow.integral('sum((u - uinf)^2)' @ ns, degree=degree*2)
ucons = solver.optimize('u', sqr, droptol=1e-15) # constrain inflow semicircle to uinf
cons = dict(u=ucons)
numpy.random.seed(seed)
sqr = domain.integral('sum((u - uinf)^2)' @ ns, degree=degree*2)
udofs0 = solver.optimize('u', sqr) * numpy.random.normal(1, .1, len(ns.ubasis)) # set initial condition to u=uinf with small random noise
state0 = dict(u=udofs0)
ures = domain.integral('(ubasis_ni d(u_i, x_j) u_j + d(ubasis_ni, x_j) sigma_ij) J(x)' @ ns, degree=9)
ures += domain.boundary['inner'].integral('(nitsche_ni (u_i - uwall_i) - ubasis_ni sigma_ij n_j) J(x)' @ ns, degree=9)
pres = domain.integral('pbasis_n d(u_k, x_k) J(x)' @ ns, degree=9)
uinertia = domain.integral('ubasis_ni u_i J(x)' @ ns, degree=9)
bbox = numpy.array([[-2,46/9],[-2,2]]) # bounding box for figure based on 16x9 aspect ratio
bezier0 = domain.sample('bezier', 5)
bezier = bezier0.subset((bezier0.eval((ns.x-bbox[:,0]) * (bbox[:,1]-ns.x)) > 0).all(axis=1))
interpolate = util.tri_interpolator(bezier.tri, bezier.eval(ns.x), mergetol=1e-5) # interpolator for quivers
spacing = .05 # initial quiver spacing
xgrd = util.regularize(bbox, spacing)
with treelog.iter.plain('timestep', solver.impliciteuler(('u', 'p'), residual=(ures, pres), inertia=(uinertia, None), arguments=state0, timestep=timestep, constrain=cons, newtontol=1e-10)) as steps:
for istep, state in enumerate(steps):
t = istep * timestep
x, u, normu, p = bezier.eval(['x', 'u', 'norm2(u)', 'p'] @ ns, **state)
ugrd = interpolate[xgrd](u)
with export.mplfigure('flow.png', figsize=(12.8,7.2)) as fig:
ax = fig.add_axes([0,0,1,1], yticks=[], xticks=[], frame_on=False, xlim=bbox[0], ylim=bbox[1])
im = ax.tripcolor(x[:,0], x[:,1], bezier.tri, p, shading='gouraud', cmap='jet')
import matplotlib.collections
ax.add_collection(matplotlib.collections.LineCollection(x[bezier.hull], colors='k', linewidths=.1, alpha=.5))
ax.quiver(xgrd[:,0], xgrd[:,1], ugrd[:,0], ugrd[:,1], angles='xy', width=1e-3, headwidth=3e3, headlength=5e3, headaxislength=2e3, zorder=9, alpha=.5)
ax.plot(0, 0, 'k', marker=(3,2,t*rotation*180/numpy.pi-90), markersize=20)
cax = fig.add_axes([0.9, 0.1, 0.01, 0.8])
cax.tick_params(labelsize='large')
fig.colorbar(im, cax=cax)
if t >= endtime:
break
xgrd = util.regularize(bbox, spacing, xgrd + ugrd * timestep)
return state0, state
def __init__(self,
nel=10,
L=15,
penalty=1e10,
ratio=1000,
override=False,
finalize=True):
L /= 5
hnel = int(L * 5 * nel // 2)
xpts = np.linspace(0, L, 2 * hnel + 1)
yzpts = np.linspace(0, 0.2, nel + 1)
domain, geom = mesh.rectilinear([xpts, yzpts])
dom1 = domain[:hnel, :]
dom2 = domain[hnel:, :]
NutilsCase.__init__(self, 'Elastic split beam', domain, geom)
E1 = self.parameters.add('ymod1', 1e10, 9e10)
E2 = self.parameters.add('ymod2', 1e10 / ratio, 9e10 / ratio)
NU = self.parameters.add('prat', 0.25, 0.42)
F1 = self.parameters.add('force1', -1e8, 1e8)
mults = [[2] + [1] * (hnel - 1) + [2] + [1] * (hnel - 1) + [2],
[2] + [1] * (nel - 1) + [2]]
basis = domain.basis('spline', degree=1,
knotmultiplicities=mults).vector(2)
blen = len(basis)
basis, *__ = fn.chain([basis, [0] * (2 * (nel + 1))])
self.bases.add('u', basis, length=blen)
self.extra_dofs = (nel + 1) * 2
self.lift += 1, np.zeros((len(basis), ))
self.constrain('u', 'left')
self.constrain('u', 'right')
MU1 = E1 / (1 + NU)
MU2 = E2 / (1 + NU)
LAMBDA1 = E1 * NU / (1 + NU) / (1 - 2 * NU)
LAMBDA2 = E2 * NU / (1 + NU) / (1 - 2 * NU)
itg_mu = fn.outer(basis.symgrad(geom)).sum([-1, -2])
itg_la = fn.outer(basis.div(geom))
self['stiffness'] += MU1, NutilsArrayIntegrand(itg_mu).prop(
domain=dom1)
self['stiffness'] += MU2, NutilsArrayIntegrand(itg_mu).prop(
domain=dom2)
self['stiffness'] += LAMBDA1, NutilsArrayIntegrand(itg_la).prop(
domain=dom1)
self['stiffness'] += LAMBDA2, NutilsArrayIntegrand(itg_la).prop(
domain=dom2)
# Penalty term ... quite hacky
K = blen // 2
ldofs = list(range(hnel * (nel + 1), (hnel + 1) * (nel + 1)))
rdofs = list(range((hnel + 1) * (nel + 1), (hnel + 2) * (nel + 1)))
ldofs += [k + K for k in ldofs]
rdofs += [k + K for k in rdofs]
L = len(ldofs)
Linds = list(range(self.ndofs - L, self.ndofs))
pen = sp.coo_matrix(((np.ones(L), (Linds, ldofs))),
shape=(self.ndofs, self.ndofs))
pen += sp.coo_matrix(((-np.ones(L), (Linds, rdofs))),
shape=(self.ndofs, self.ndofs))
self['penalty'] += 1, ScipyArrayIntegrand(sp.csc_matrix(pen + pen.T))
# Even more hacky for the ROM part
bnd_lft = domain[:hnel, :].boundary['right']
bnd_rgt = domain[hnel:, :].boundary['left']
pts, wts = bnd_lft.elements[0].reference.getischeme('gauss5')
penalty_mx = np.zeros((self.ndofs, self.ndofs))
for el_lft, el_rgt in zip(bnd_lft.elements, bnd_rgt.elements):
udiff = (
basis.eval(_points=pts,
_transforms=(el_lft.transform, el_lft.opposite)) -
basis.eval(_points=pts,
_transforms=(el_rgt.transform, el_rgt.opposite)))
penalty_mx += (udiff[:, :, _, :] * udiff[:, _, :, :] *
wts[:, _, _, _]).sum((0, -1))
self['penalty-rom'] += 1e20, sp.csc_matrix(penalty_mx)
normdot = fn.matmat(basis, geom.normal())
force_bnd = domain[hnel - 11:hnel - 1, :].boundary['top']
self['forcing'] += F1, NutilsArrayIntegrand(normdot).prop(
domain=force_bnd)
self['u-h1s'] = self['stiffness']
self['u-h1s-l'] = self['stiffness']
self['u-h1s-r'] = self['stiffness']
self['u-h1s-e'] = self['stiffness']
self.verify()
import click
import numpy as np
from nutils import log, config, function as fn
from aroma import cases, solvers, util, quadrature, reduction, ensemble as ens, visualization
from aroma.affine import NumpyArrayIntegrand, integrate
import multiprocessing
import matplotlib.pyplot as plt
def get_exforce(case, mu):
v, p = case.exact(mu, ('v', 'p'))
geom = case.geometry(mu)
force = p * geom.normal() - fn.matmat(v.grad(geom),
geom.normal()) / mu['re']
return case.domain.boundary['bottom'].integrate(force,
ischeme='gauss9',
geometry=geom)
def get_locforce(case, mu, lhs):
return case['force'](mu, cont=(lhs, None))
def get_globforce(case, mu, lhs):
wx, wy, l = case['xforce'](mu), case['yforce'](mu), case.lift(mu)
u = lhs + l
getf = lambda w: (case['divergence'](mu, cont=(w, u)) + case['laplacian'](
mu, cont=(w, u)) + integrate(case['convection']
(mu, cont=(w, u, u))) - case['forcing']
(mu, cont=(w, )))
def __init__(self, nelems=10, piola=False, degree=2):
pts = np.linspace(0, 1, nelems + 1)
domain, geom = mesh.rectilinear([pts, pts])
NutilsCase.__init__(self, 'Abdulahque Manufactured Solution', domain,
geom)
RE = 1 / self.parameters.add('re', 100.0, 150.0)
T = self.parameters.add('time', 0.0, 10.0)
# Add bases and construct a lift function
vbasis, pbasis = mk_bases(self, piola, degree)
self.constrain('v', 'bottom')
# self.constrain('v', 'top')
# self.constrain('v', 'left')
# self.constrain('v', 'right')
self.lift += 1, np.zeros(len(vbasis))
self['divergence'] -= 1, fn.outer(vbasis.div(geom), pbasis)
self['divergence'].freeze(lift=(1, ))
self['laplacian'] += RE, fn.outer(vbasis.grad(geom)).sum((-1, -2))
self['convection'] += 1, NutilsDelayedIntegrand('w_ia u_jb v_ka,b',
'ijk',
'wuv',
x=geom,
w=vbasis,
u=vbasis,
v=vbasis)
self['v-h1s'] += 1, fn.outer(vbasis.grad(geom)).sum((-1, -2))
self['v-l2'] += 1, fn.outer(vbasis).sum((-1, ))
self['p-l2'] += 1, fn.outer(pbasis)
# Body force
x, y = geom
h = T
h1 = 1
f = 4 * (x - x**2)**2
f1 = f.grad(geom)[0]
f2 = f1.grad(geom)[0]
f3 = f2.grad(geom)[0]
g = 4 * (y - y**2)**2
g1 = g.grad(geom)[1]
g2 = g1.grad(geom)[1]
g3 = g2.grad(geom)[1]
# Body force
self['forcing'] += h**2, fn.matmat(
vbasis,
fn.asarray([
(g1**2 - g * g2) * f * f1,
(f1**2 - f * f2) * g * g1,
]))
self['forcing'] += RE * h, fn.matmat(
vbasis, fn.asarray([-f * g3, f3 * g + 2 * f1 * g2]))
self['forcing'] += h1, fn.matmat(vbasis, fn.asarray([f * g1, -f1 * g]))
# Neumann conditions
mx = fn.asarray([[f1 * g1, f * g2], [-f2 * g, -f1 * g1]])
hh = fn.matmat(mx, geom.normal()) - f1 * g1 * geom.normal()
self['forcing'] += RE * h, NutilsArrayIntegrand(fn.matmat(
vbasis,
hh)).prop(domain=domain.boundary['left'] | domain.boundary['right']
| domain.boundary['top'])
def exact(self, mu, field):
scale = mu['w']**(self.power-1) * mu['h']**(self.power-1)
retval = scale * self._exact_solutions[field]
if field == 'v':
return fn.matmat(fn.asarray([[mu['w'], 0], [0, mu['h']]]), retval)
return retval
def __init__(self,
nel=10,
ndim=2,
L=15,
override=False,
finalize=True,
graded=False):
L /= 5
if graded:
# HACK!
xpts = _graded(0, L, int(L * 3 * nel + 1), 1.04)
yzpts = _graded(0, 0.1, nel // 2 + 1, 1.3)
yzpts = np.hstack([yzpts[:-1], 0.2 - yzpts[::-1]])
else:
xpts = np.linspace(0, L, int(L * 5 * nel + 1))
yzpts = np.linspace(0, 0.2, nel + 1)
if ndim == 2:
domain, geom = mesh.rectilinear([xpts, yzpts])
else:
domain, geom = mesh.rectilinear([xpts, yzpts, yzpts])
NutilsCase.__init__(self, 'Elastic beam', domain, geom)
E = self.parameters.add('ymod', 1e10, 9e10)
NU = self.parameters.add('prat', 0.25, 0.42)
F1 = self.parameters.add('force1', -0.4e6, 0.4e6)
F2 = self.parameters.add('force2', -0.2e6, 0.2e6)
if ndim == 3:
F3 = self.parameters.add('force3', -0.2e6, 0.2e6)
basis = domain.basis('spline', degree=1).vector(ndim)
self.bases.add('u', basis, length=len(basis))
self.lift += 1, np.zeros((len(basis), ))
self.constrain('u', 'left')
MU = E / (1 + NU)
LAMBDA = E * NU / (1 + NU) / (1 - 2 * NU)
self['stiffness'] += MU, fn.outer(basis.symgrad(geom)).sum([-1, -2])
self['stiffness'] += LAMBDA, fn.outer(basis.div(geom))
normdot = fn.matmat(basis, geom.normal())
irgt = NutilsArrayIntegrand(normdot).prop(
domain=domain.boundary['right'])
ibtm = NutilsArrayIntegrand(normdot).prop(
domain=domain.boundary['bottom'])
itop = NutilsArrayIntegrand(normdot).prop(
domain=domain.boundary['top'])
self['forcing'] += F1, irgt
self['forcing'] -= F2, ibtm
self['forcing'] += F2, itop
if ndim == 3:
ifrt = NutilsArrayIntegrand(normdot).prop(
domain=domain.boundary['front'])
ibck = NutilsArrayIntegrand(normdot).prop(
domain=domain.boundary['back'])
self['forcing'] -= F3, ifrt
self['forcing'] += F3, ibck
self['u-h1s'] += 1, fn.outer(basis.grad(geom)).sum([-1, -2])
self.verify()
