def evolve(nx, C, tmax, xmax=None):
xmin = 0.0
if xmax == None:
xmax = 1.0
# create a dummy patch to store some info in the same way the MG
# solver will
myGrid = patch1d.grid1d(nx, ng=1, xmin=xmin, xmax=xmax)
# initialize the data
phi = myGrid.scratchArray()
# initial solution -- this fills the GC too
phi[:] = phi_a(myGrid, 0.0)
# time info
dt = C * 0.5 * myGrid.dx**2 / k
t = 0.0
# evolve
while (t < tmax):
if (t + dt > tmax):
dt = tmax - t
# create the multigrid object
a = multigrid.ccMG1d(nx,
xmin=xmin,
xmax=xmax,
alpha=1.0,
beta=0.5 * dt * k,
xlBCtype="neumann",
xrBCtype="neumann",
verbose=0)
# initialize the RHS
a.initRHS(phi + 0.5 * dt * k * lap(a.solnGrid, phi))
# initialize the solution to 0
a.initZeros()
# solve to a relative tolerance of 1.e-11
a.solve(rtol=1.e-11)
# get the solution
v = a.getSolution()
# store the new solution
phi[:] = v[:]
t += dt
return a.solnGrid, phi
def evolve(nx, C, tmax, xmax=None):
xmin = 0.0
if xmax == None: xmax = 1.0
# create a dummy patch to store some info in the same way the MG
# solver will
myGrid = patch1d.grid1d(nx, ng=1,
xmin=xmin, xmax=xmax)
# initialize the data
phi = myGrid.scratchArray()
# initial solution -- this fills the GC too
phi[:] = phi_a(myGrid, 0.0)
# time info
dt = C*0.5*myGrid.dx**2/k
t = 0.0
# evolve
while (t < tmax):
if (t + dt > tmax):
dt = tmax - t
# create the multigrid object
a = multigrid.ccMG1d(nx, xmin=xmin, xmax=xmax,
alpha = 1.0, beta = 0.5*dt*k,
xlBCtype="neumann", xrBCtype="neumann",
verbose=0)
# initialize the RHS
a.initRHS(phi + 0.5*dt*k*lap(a.solnGrid, phi))
# initialize the solution to 0
a.initZeros()
# solve to a relative tolerance of 1.e-11
a.solve(rtol=1.e-11)
# get the solution
v = a.getSolution()
# store the new solution
phi[:] = v[:]
t += dt
return a.solnGrid, phi
def __init__(self,
nx,
xmin=0.0,
xmax=1.0,
xlBCtype="dirichlet",
xrBCtype="dirichlet",
alpha=0.0,
beta=-1.0,
verbose=0):
self.nx = nx
self.ng = 1
self.xmin = xmin
self.xmax = xmax
self.alpha = alpha
self.beta = beta
self.nsmooth = 10
self.nbottomSmooth = 50
self.maxCycles = 100
self.verbose = verbose
# a small number used in computing the error, so we don't divide by 0
self.small = 1.e-16
# keep track of whether we've initialized the solution
self.initializedSolution = 0
self.initializedRHS = 0
# assume that self.nx = 2^(nlevels-1)
# this defines nlevels such that we end exactly on a 2 zone grid
self.nlevels = int(math.log(self.nx) / math.log(2.0))
# a multigrid object will be a list of grids
self.grids = []
# create the grids. Here, self.grids[0] will be the coarsest
# grid and self.grids[nlevel-1] will be the finest grid
# we store the solution, v, the rhs, f.
i = 0
nx_t = 2
if (self.verbose):
print "alpha = ", self.alpha
print "beta = ", self.beta
while (i < self.nlevels):
# create the grid
myGrid = patch1d.grid1d(nx_t, ng=self.ng, xmin=xmin, xmax=xmax)
# add a ccData2d object for this level to our list
self.grids.append(patch1d.ccData1d(myGrid, dtype=numpy.float64))
# create the boundary condition object
bcObj = patch1d.bcObject(xlb=xlBCtype, xrb=xrBCtype)
self.grids[i].registerVar("v", bcObj)
self.grids[i].registerVar("f", bcObj)
self.grids[i].registerVar("r", bcObj)
self.grids[i].create()
if self.verbose:
print self.grids[i]
nx_t = nx_t * 2
i += 1
# provide coordinate and indexing information for the solution mesh
solnGrid = self.grids[self.nlevels - 1].grid
self.ilo = solnGrid.ilo
self.ihi = solnGrid.ihi
self.x = solnGrid.x
self.dx = solnGrid.dx
self.solnGrid = solnGrid
# store the source norm
self.sourceNorm = 0.0
# after solving, keep track of the number of cycles taken, the
# relative error from the previous cycle, and the residual error
# (normalized to the source norm)
self.numCycles = 0
self.residualError = 1.e33
self.relativeError = 1.e33
