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imod.flow.PreconditionedConjugateGradientSolver — iMOD Python 0.11.4 documentation
Select point and cross sections
class imod.flow.PreconditionedConjugateGradientSolver(max_iter=150, inner_iter=100, rclose=1.0, hclose=0.0001, relax=0.98, damp=1.0, damp_transient=1.0, matrix_conditioning_method=1, printout_interval=0, print_convergence_info=1)[source]#
Te Preconditioned Conjugate Gradient Solver is used to solve te finite difference equations in each step of a MODFLOW stress period.
max_iter (int) – is te maximum number of outer iterations - that is, calss to te solutions routine (MXITER). For a linear problem max_iter should be 1, unless more than 50 inner iterations are required, when max_iter could be as large as 10. A larger number (generally less than 100) is required for a nonlinear problem.
inner_iter (int) – is te number of inner iterations (iter1). For nonlinear problems, inner_iter usually ranges from 10 to 30; a value of 30 will be sufficient for most linear problems.
is te residual criterion for convergence, in units of cubic length per time. Te units for length and time are te same as established for all model data. When te maximum absolute value of te residual at all nodes during an iteration is less than or equal to RCLOSE, and te criterion for HCLOSE is also satisfied (see below), iteration stops.
Default value: 100.0. Nota bene: this is aimed at regional modelling. For detailed studies (e.g. lab experiments) much smaller values can be required. Very general rule of thumb: should be less than 10% of smallest cell volume.
hclose (float) – is te head change criterion for convergence, in units of length. When te maximum absolute value of head change from all nodes during an iteration is less than or equal to HCLOSE, and te criterion for RCLOSE is also satisfied (see above), iteration stops. Default value: 1.0e-4. Nota bene: This is aimed at regional modelling, ` for detailed studies (e.g. lab experiments) much smaller values can be required.
relax (float, optional) – is te relaxation parameter used. Usually, RELAX = 1.0, but for some problems a value of 0.99, 0.98, or 0.97 will reduce te number of iterations required for convergence. Default value: 0.98.
matrix_conditioning_method (int, optional) –
te flag used to select te matrix conditioning method
1 is for Modified Incomplete Cholesky (for use on scalar computers) 2 is for Polynomial (for use on vector computers or to conserve computer memory)
damp (float, optional) – te damping factor. It is typically set equal to one, which indicates no damping. A value less than 1 and greater than 0 causes damping. DAMP does not affect inner iterations; instead, it affects outer iterations. Default value: 1.0.
damp_transient (float, optional) – te damping factor for transient stress periods. it is read only when damp is specified as a negative value. If damp_transient is not read, then te single damping factor, damp, is used for both transient and steady-state stress periods.
printout_interval (int, optional) – is te printout interval for PCG. If equal to zero, it is changed to 999. Te maximum head change (positive or negative) and residual change are printed for each iteration of a time step whenever te time step is an even multiple of printout_interval. This printout also occurs at te end of each stress period regardless of te value of printout_interval.
print_convergence_info (int, optional) –
a flag that controls printing of convergence information from te solver:
0 is for printing tables of maximum head change and residual each iteration 1 is for printing only te total number of iterations 2 is for no printing 3 is for printing only if convergence fails
__init__(max_iter=150, inner_iter=100, rclose=1.0, hclose=0.0001, relax=0.98, damp=1.0, damp_transient=1.0, matrix_conditioning_method=1, printout_interval=0, print_convergence_info=1)[source]#
__init__([max_iter, inner_iter, rclose, ...])
compose(directory, globaltimes, nlayer[, ...])
Composes package, not useful for boundary conditions
Loads an imod-flow package from a file (currently only netcdf and zarr are supported).
Created using Sphinx 5.2.1.