- class imod.wq.PreconditionedConjugateGradientSolver(max_iter=150, inner_iter=100, rclose=1000.0, hclose=0.0001, relax=0.98, damp=1.0)[source]#
The Preconditioned Conjugate Gradient Solver is used to solve the finite difference equations in each step of a MODFLOW stress period.
max_iter (int) – is the maximum number of outer iterations - that is, calss to the 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 the 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.
rclose (float) –
is the residual criterion for convergence, in units of cubic length per time. The units for length and time are the same as established for all model data. When the maximum absolute value of the residual at all nodes during an iteration is less than or equal to RCLOSE, and the 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 the head change criterion for convergence, in units of length. When the maximum absolute value of head change from all nodes during an iteration is less than or equal to HCLOSE, and the 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 the relaxation parameter used. Usually, RELAX = 1.0, but for some problems a value of 0.99, 0.98, or 0.97 will reduce the number of iterations required for convergence. Default value: 0.98.
damp (float, optional) – is the 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.
__init__([max_iter, inner_iter, rclose, ...])
Loads an imod-wq package from a file (currently only netcdf and zarr are supported).
write_netcdf(directory, pkgname[, ...])
Write to netcdf.