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Generalise linear solvers #648

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8d2860d
Create branch
JHopeCollins Aug 7, 2025
bc55637
New moist solver for 5 variables works
atb1995 Aug 7, 2025
f1d8126
Temprary save - working toward aP
atb1995 Aug 7, 2025
99ca85b
remove aP from ConvectiveSWESolver
JHopeCollins Aug 8, 2025
9cfe8b1
update linearisation map and default solver
tommbendall Aug 8, 2025
807c7c0
Saving progress before merge in of linearisation map
atb1995 Aug 8, 2025
5e51f2c
Merge remote-tracking branch 'origin/TBendall/SolverEqns' into auxili…
atb1995 Aug 8, 2025
e508449
PC for calculating a schur complement using slate
JHopeCollins Aug 8, 2025
593f7ba
remove MoistConvectiveSWSolver
JHopeCollins Aug 8, 2025
32ce053
Revert "Merge remote-tracking branch 'origin/TBendall/SolverEqns' int…
atb1995 Aug 8, 2025
6ae2e4b
Monolithic solver for hard coded linear thermal eqns added
atb1995 Aug 8, 2025
55f7cc0
added monolithic solver for thermal shallow water eqns
atb1995 Aug 8, 2025
1f636e4
Remove declaration..
atb1995 Aug 8, 2025
a326eda
refactor monolithic thermal swe linear solver
JHopeCollins Aug 14, 2025
f036239
Merge branch 'main' into auxiliary-equation-pc
JHopeCollins Sep 12, 2025
fd6c755
expunge shallow water linear solvers
JHopeCollins Sep 12, 2025
86da3dc
boussinesq schur complement?
JHopeCollins Sep 12, 2025
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63 changes: 61 additions & 2 deletions examples/boussinesq/skamarock_klemp_compressible.py
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@
from gusto import (
Domain, IO, OutputParameters, SemiImplicitQuasiNewton, SSPRK3, DGUpwind,
TrapeziumRule, SUPGOptions, Divergence, Perturbation, CourantNumber,
BoussinesqParameters, BoussinesqEquations, BoussinesqSolver,
BoussinesqParameters, BoussinesqEquations, BoussinesqSolver, LinearTimesteppingSolver,
boussinesq_hydrostatic_balance
)

Expand Down Expand Up @@ -91,7 +91,66 @@ def skamarock_klemp_compressible_bouss(
]

# Linear solver
linear_solver = BoussinesqSolver(eqns)
solver_parameters = {
'ksp_monitor_true_residual': None,
'ksp_view': ':ksp_view.log',
'ksp_error_if_not_converged': None,
'mat_type': 'matfree',
'ksp_type': 'preonly',
'pc_type': 'fieldsplit',
'pc_fieldsplit_type': 'schur',
'pc_fieldsplit_schur_fact_type': 'full',
'pc_fieldsplit_1_fields': '0,1',
'pc_fieldsplit_0_fields': '2', # eliminate temperature
'fieldsplit_theta': {
'ksp_type': 'preonly',
'pc_type': 'python',
'pc_python_type': 'firedrake.AssembledPC',
'assembled_pc_type': 'bjacobi',
'assembled_sub_pc_type': 'ilu',
},
'fieldsplit_1': {
'ksp_monitor': None,
'ksp_type': 'preonly',
'pc_type': 'python',
'pc_python_type': 'gusto.AuxiliaryPC',
'aux': {
'mat_type': 'matfree',
'pc_type': 'python',
'pc_python_type': 'firedrake.HybridizationPC',
'hybridization': {
'ksp_type': 'cg',
'pc_type': 'gamg',
'ksp_rtol': 1e-8,
'mg_levels': {
'ksp_type': 'chebyshev',
'ksp_max_it': 2,
'pc_type': 'bjacobi',
'sub_pc_type': 'ilu'
},
'mg_coarse': {
'ksp_type': 'preonly',
'pc_type': 'lu',
'pc_factor_mat_solver_type': 'mumps',
},
},
},
},
}

def trace_nullsp(T):
return VectorSpaceBasis(constant=True)

appctx = {
'auxform': eqns.schur_complement_form(alpha=0.5),
"trace_nullspace": trace_nullsp,
}

linear_solver = LinearTimesteppingSolver(
eqns, alpha=0.5, options_prefix="boussinesq",
solver_parameters=solver_parameters,
appctx=appctx
)

# Time stepper
stepper = SemiImplicitQuasiNewton(
Expand Down
68 changes: 64 additions & 4 deletions examples/compressible_euler/skamarock_klemp_nonhydrostatic.py
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Original file line number Diff line number Diff line change
Expand Up @@ -13,12 +13,10 @@
"""
from argparse import ArgumentParser, ArgumentDefaultsHelpFormatter

from petsc4py import PETSc
PETSc.Sys.popErrorHandler()
import itertools
from firedrake import (
as_vector, SpatialCoordinate, PeriodicIntervalMesh, ExtrudedMesh, exp, sin,
Function, pi, COMM_WORLD, sqrt
PETSc, Function, pi, COMM_WORLD, sqrt
)
import numpy as np
from gusto import (
Expand All @@ -28,6 +26,7 @@
compressible_hydrostatic_balance, RungeKuttaFormulation, CompressibleSolver,
hydrostatic_parameters, SubcyclingOptions,
)
PETSc.Sys.popErrorHandler()

skamarock_klemp_nonhydrostatic_defaults = {
'ncolumns': 150,
Expand Down Expand Up @@ -138,6 +137,65 @@ def skamarock_klemp_nonhydrostatic(
DGUpwind(eqns, "theta", ibp=theta_opts.ibp)
]

lu_params = {
'ksp_type': 'preonly',
'pc_type': 'lu',
'pc_factor_mat_solver_type': 'mumps',
}

gamg_params = {
'ksp_type': 'fgmres',
'ksp_rtol': 1.0e-8,
'ksp_atol': 1.0e-8,
'ksp_max_it': 100,
'pc_type': 'gamg',
'pc_gamg_sym_graph': None,
'mg_levels': {
'ksp_type': 'gmres',
'ksp_max_it': 5,
'pc_type': 'bjacobi',
'sub_pc_type': 'ilu',
},
'mg_coarse': lu_params
}

scpc_parameters = {
'mat_type': 'matfree',
'ksp_type': 'preonly',
'pc_type': 'python',
'pc_python_type': 'firedrake.SCPC',
'pc_sc_eliminate_fields': '0, 1',
'condensed_field': gamg_params
}

slate_parameters = {
'mat_type': 'matfree',
'ksp_type': 'preonly',
'pc_type': 'fieldsplit',
'pc_fieldsplit_type': 'additive',
'pc_fieldsplit_type': 'schur',
'pc_fieldsplit_schur_fact_type': 'full',
'pc_fieldsplit_0_fields': '0,1',
'pc_fieldsplit_1_fields': '2',
'fieldsplit_0': {
'ksp_type': 'preonly',
'pc_type': 'python',
'pc_python_type': 'firedrake.AssembledPC',
'assembled_pc_type': 'ilu',
},
'fieldsplit_1': {
'ksp_type': 'preonly',
'pc_type': 'python',
'pc_python_type': 'gusto.SlateSchurPC',
'pc_slateschur_fields': 2,
'slateschur': gamg_params
},
}

solver_parameters = scpc_parameters
# solver_parameters = slate_parameters


# Linear solver
if hydrostatic:
if timestepper == 'TR-BDF2':
Expand All @@ -148,7 +206,9 @@ def skamarock_klemp_nonhydrostatic(
overwrite_solver_parameters=True
)
else:
linear_solver = CompressibleSolver(eqns)
linear_solver = CompressibleSolver(
eqns, solver_parameters=solver_parameters,
overwrite_solver_parameters=True)

# Time stepper
if timestepper == 'TR-BDF2':
Expand Down
58 changes: 56 additions & 2 deletions examples/shallow_water/linear_thermal_galewsky_jet.py
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@
Domain, IO, OutputParameters, SemiImplicitQuasiNewton, DefaultTransport,
DGUpwind, ForwardEuler, ShallowWaterParameters, NumericalIntegral,
LinearThermalShallowWaterEquations, GeneralIcosahedralSphereMesh,
ZonalComponent, ThermalSWSolver, lonlatr_from_xyz, xyz_vector_from_lonlatr,
ZonalComponent, LinearTimesteppingSolver, lonlatr_from_xyz, xyz_vector_from_lonlatr,
RelativeVorticity, MeridionalComponent
)

Expand Down Expand Up @@ -84,7 +84,61 @@ def linear_thermal_galewsky_jet(
transport_methods = [DefaultTransport(eqns, "D"), DGUpwind(eqns, "b")]

# Linear solver
linear_solver = ThermalSWSolver(eqns)
solver_parameters = {
'ksp_monitor_true_residual': None,
'ksp_view': ':ksp_view.log',
'ksp_error_if_not_converged': None,
'mat_type': 'matfree',
'ksp_type': 'preonly',
'pc_type': 'fieldsplit',
'pc_fieldsplit_type': 'schur',
'pc_fieldsplit_schur_fact_type': 'full',
'pc_fieldsplit_1_fields': '0,1',
'pc_fieldsplit_0_fields': '2', # eliminate temperature
'fieldsplit_L2': {
'ksp_monitor': None,
'ksp_type': 'preonly',
'pc_type': 'python',
'pc_python_type': 'firedrake.AssembledPC',
'assembled_pc_type': 'bjacobi',
'assembled_sub_pc_type': 'ilu',
},
'fieldsplit_1': {
'ksp_monitor': None,
'ksp_type': 'preonly',
'pc_type': 'python',
'pc_python_type': 'gusto.AuxiliaryPC',
'aux': {
'mat_type': 'matfree',
'pc_type': 'python',
'pc_python_type': 'firedrake.HybridizationPC',
'hybridization': {
'ksp_type': 'cg',
'pc_type': 'gamg',
'ksp_rtol': 1e-8,
'mg_levels': {
'ksp_type': 'chebyshev',
'ksp_max_it': 2,
'pc_type': 'bjacobi',
'sub_pc_type': 'ilu'
},
'mg_coarse': {
'ksp_type': 'preonly',
'pc_type': 'lu',
'pc_factor_mat_solver_type': 'mumps',
},
},
},
},
}

appctx = {'auxform': eqns.schur_complement_form(alpha=0.5)}

linear_solver = LinearTimesteppingSolver(
eqns, alpha=0.5, options_prefix="swe",
solver_parameters=solver_parameters,
appctx=appctx
)

# Time stepper
stepper = SemiImplicitQuasiNewton(
Expand Down
56 changes: 53 additions & 3 deletions examples/shallow_water/moist_convective_williamson_2.py
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -13,12 +13,15 @@
"""

from argparse import ArgumentParser, ArgumentDefaultsHelpFormatter
from firedrake import SpatialCoordinate, sin, cos, exp, Function
from firedrake import (
SpatialCoordinate, sin, cos, exp, Function, errornorm, norm,
VectorSpaceBasis, COMM_WORLD
)
from gusto import (
Domain, IO, OutputParameters, SemiImplicitQuasiNewton, SSPRK3, DGUpwind,
TrapeziumRule, ShallowWaterParameters, ShallowWaterEquations,
ZonalComponent, MeridionalComponent, SteadyStateError, lonlatr_from_xyz,
DG1Limiter, InstantRain, MoistConvectiveSWSolver, ForwardEuler,
DG1Limiter, InstantRain, ForwardEuler, LinearTimesteppingSolver,
RelativeVorticity, SWSaturationAdjustment, WaterVapour, CloudWater, Rain,
GeneralIcosahedralSphereMesh, xyz_vector_from_lonlatr
)
Expand Down Expand Up @@ -127,7 +130,46 @@ def sat_func(x_in):
SSPRK3(domain, "rain", limiter=limiter)
]

linear_solver = MoistConvectiveSWSolver(eqns)
solver_parameters = {
'mat_type': 'matfree',
'ksp_type': 'preonly',
"pc_type": "fieldsplit",
"pc_fieldsplit_type": "additive",
"pc_fieldsplit_0_fields": "0,1", # (u, D)
"pc_fieldsplit_1_fields": "2,3,4", # (scalars,)
"fieldsplit_0": { # hybridisation on the (u,D) system
'ksp_monitor_true_residual': None,
'ksp_type': 'preonly',
'pc_type': 'python',
'pc_python_type': 'firedrake.HybridizationPC',
'hybridization': {
'ksp_type': 'cg',
'pc_type': 'gamg',
'ksp_rtol': 1e-8,
'mg_levels': {
'ksp_type': 'chebyshev',
'ksp_max_it': 2,
'pc_type': 'bjacobi',
'sub_pc_type': 'ilu'
}
}
},
"fieldsplit_1": { # Don't touch the transported fields
"ksp_type": "preonly",
"pc_type": "none"
},
}

# Provide callback for the nullspace of the trace system
def trace_nullsp(T):
return VectorSpaceBasis(constant=True, comm=COMM_WORLD)
appctx = {"trace_nullspace": trace_nullsp}

linear_solver = LinearTimesteppingSolver(
eqns, alpha=0.5,
reference_dependent=True,
solver_parameters=solver_parameters,
options_prefix="swe", appctx=appctx)

# Physics schemes
sat_adj = SWSaturationAdjustment(
Expand Down Expand Up @@ -158,6 +200,8 @@ def sat_func(x_in):
D0 = stepper.fields("D")
v0 = stepper.fields("water_vapour")

D_init = Function(D0.function_space())

uexpr = xyz_vector_from_lonlatr(u_max*cos(phi), 0, 0, (x, y, z))
g = parameters.g
w = Omega*radius*u_max + (u_max**2)/2
Expand All @@ -184,6 +228,8 @@ def sat_func(x_in):
D0.interpolate(Dexpr)
v0.interpolate(vexpr)

D_init.interpolate(Dexpr)

# Set reference profiles
Dbar = Function(D0.function_space()).assign(mean_depth)
stepper.set_reference_profiles([('D', Dbar)])
Expand All @@ -194,6 +240,10 @@ def sat_func(x_in):

stepper.run(t=0, tmax=tmax)

error_D = errornorm(D0, D_init, mesh=mesh)/norm(D_init, mesh=mesh)

print("Error D:", error_D)

# ---------------------------------------------------------------------------- #
# MAIN
# ---------------------------------------------------------------------------- #
Expand Down
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