PATCH — Common Modules

The common/ directory contains the modules shared by all PATCH backends. They define the problem physics, boundary and initial conditions, I/O, convergence parameters, and the base type that every backend extends.

Source Layout

File	Module	Role
adam_patch_common_object.F90	adam_patch_common_object	patch_common_object base type and initialize_common
adam_patch_bc_object.F90	adam_patch_bc_object	Boundary conditions handler
adam_patch_ic_object.F90	adam_patch_ic_object	Initial conditions handler
adam_patch_io_object.F90	adam_patch_io_object	I/O options and residuals log
adam_patch_time_object.F90	adam_patch_time_object	Convergence and output frequency parameters
adam_patch_common_library.F90	adam_patch_common_library	Barrel re-export of all common modules

patch_common_object

patch_common_object is the base type for all PATCH backends. It aggregates the ADAM framework objects, the FLAIL linear algebra handler, and the PATCH-specific sub-objects.

Data Members

Member	Type	Description
mpih	mpih_object	MPI handler
adam	adam_object	Core ADAM object (tree, grid, field, I/O)
field	field_object*	Pointer alias to adam%field
grid	grid_object*	Pointer alias to adam%grid
amr	amr_object	AMR marker handler
ib	ib_object	Immersed boundary handler
flail	flail_object	FLAIL linear algebra / smoothing handler
io	patch_io_object	I/O configuration
ic	patch_ic_object	Initial conditions
bc	patch_bc_object	Boundary conditions
time	patch_time_object	Convergence and output frequency
q	real(R8P)(:,:,:,:,:)	Scalar potential φ — shape (nv, ni, nj, nk, nb)
r	real(R8P)(:,:,:,:,:)	Source distribution f — shape (nv, ni, nj, nk, nb)
q_name	character(3)(1)	Output label for q (fixed to 'phi')
ngc, ni, nj, nk, nb	integer(I4P)*	Pointer aliases to grid/field dimension scalars
blocks_number	integer(I4P)*	Pointer alias to field%blocks_number
nv	integer(I4P)*	Pointer alias to field%nv (always 1 for PATCH)

Methods

Procedure	Description
allocate_common	Allocates r with ghost-cell bounds (nv, 1-ngc:ni+ngc, …, nb)
initialize_common	Full initialisation sequence (see below)

initialize_common Sequence

initialize_common sets up the entire simulation state:

1. mpih%initialize — start MPI, query rank and memory
2. io%initialize(filename) — parse INI file
3. bc%initialize — load BC configuration
4. adam%grid%initialize — set domain bounds, resolution, BC types
5. adam%compute_blocks_number — estimate block count from available memory (nv = 1, fields_number = 80)
6. adam%initialize — build AMR tree (11 nodes), field (nv=1), maps; allocates q
7. adam%refine_uniform — apply initial uniform refinement levels from INI
8. adam%prune — prune tree according to ijkl_prune settings
9. amr%initialize — load AMR marker configuration
10. time%initialize — load convergence parameters
11. ic%initialize — load IC configuration
12. ib%initialize — load IB body geometry
13. flail%initialize — load linear algebra (smoothing method and iteration counts)
14. allocate_common — allocate r
15. adam%io%initialize — register r as 'rho' field for output

patch_bc_object

Manages Dirichlet boundary conditions on the six domain faces.

Supported BC Types

Identifier	INI value	Description
BC_DIRICHLET	dirichlet	Fix φ to a constant value on the face

Data Members

Member	Description
bc_type(6)	BC type index for each face (1 = Dirichlet)
q(:,:)	Prescribed φ value for each face and variable

INI Configuration

[bc_x_min]
type = dirichlet
phi  = 0.0

[bc_x_max]
type = dirichlet
phi  = 0.0

[bc_y_min]
type = dirichlet
phi  = 0.0

[bc_y_max]
type = dirichlet
phi  = 0.0

[bc_z_min]
type = dirichlet
phi  = 0.0

[bc_z_max]
type = dirichlet
phi  = 0.0

Methods

Procedure	Description
initialize	Initialises MPI and calls load_from_file
load_from_file	Reads type and φ value for all six faces
description	Returns a human-readable summary

patch_ic_object

Sets the initial distribution of the source term r (forcing function f).

Supported IC Types

Identifier	type key	Description
IC_TYPE_GAUSS	gauss	Gaussian centred at $(0.5,0.5,0.5)$ with variance ${\sigma }^2=0.01$

The Gaussian IC is defined pointwise as:

$$r_{i,j,k}=\exp (-\frac{(x_i-0.5{)}^2+(y_j-0.5{)}^2+(z_k-0.5{)}^2}{0.01})$$

Data Members

Member	Description
ic_type	Selected IC type string
amr_iterations	Number of AMR refinement cycles to apply after imposing IC
regions_number	Number of IC regions
r(1, regions_number)	Source amplitude per region
emin(3, regions_number)	Bounding box minimum corner per region
emax(3, regions_number)	Bounding box maximum corner per region

INI Configuration

[initial_conditions]
type           = gauss
amr_iterations = 2
regions_number = 1

[initial_conditions_region_1]
r      = 1.0
emin_x = 0.0
emin_y = 0.0
emin_z = 0.0
emax_x = 1.0
emax_y = 1.0
emax_z = 1.0

Methods

Procedure	Description
initialize	Initialises MPI and calls load_from_file
load_from_file	Reads type, region count, and per-region parameters
set_initial_conditions	Fills r array according to the selected IC type
description	Returns a human-readable summary

patch_io_object

Manages all I/O options: output frequency, restart, and the residuals log file.

Data Members and INI Keys

INI section: [IO]

INI key	Member	Default	Description
output_basename	output_basename	—	Basename for output files
it_save	it_save	100	Main output iteration frequency
restart	restart	.false.	Enable restart from existing files
restart_basename	restart_basename	—	Basename for restart files
restart_save	restart_save	100	Restart checkpoint frequency
residuals_save	residuals_save	10	Residuals log write frequency
save_memory_status	save_memory_status	.false.	Log memory allocation status

[IO]
output_basename   = results/patch
it_save           = 50
restart           = .false.
restart_basename  = restart/patch
restart_save      = 100
residuals_save    = 10
save_memory_status = .false.

Residuals Log

The residuals file is written to {output_basename}-residuals.dat with columns:

VARIABLES="it" "time" "blocks_number" "rq1"

One line is written per residuals_save iterations. The rq value is the MPI-reduced L2 norm of dq normalised by the number of cells.

Methods

Procedure	Description
initialize	Opens and parses the INI file
load_from_file	Reads all IO options
open_file_residuals	Opens the residuals log file and writes the header
close_file_residuals	Closes the residuals log file
save_residuals	Appends one record to the residuals log
description	Returns a human-readable summary

patch_time_object

Holds iteration counters, convergence parameters, and output frequency for the solver loop. PATCH is an iterative (not time-marching) solver; the time and CFL fields are present for framework compatibility.

Data Members and INI Keys

INI section: [time]

INI key	Member	Default	Description
it_max	it_max	-1	Maximum iterations (-1 = no limit)
time_max	time_max	1.0	Maximum pseudo-time (used when it_max ≤ 0)
CFL	CFL	0.3	CFL number (framework compatibility)

[time]
it_max   = 500
time_max = 1.0
CFL      = 0.3

Termination Criteria

The solver exits if either condition is met:

Condition	Description
dq_max < tolerance	Residual falls below FLAIL tolerance (primary criterion)
it >= it_max and it_max > 0	Iteration budget exhausted
time >= time_max and it_max ≤ 0	Pseudo-time budget exhausted

Methods

Procedure	Description
initialize	Initialises MPI and calls load_from_file
load_from_file	Reads it_max, time_max, CFL
is_to_save	Returns .true. when data should be written at current iteration
print_progress	Prints iteration count, step, pseudo-time, and percentage to stdout
description	Returns a human-readable summary

adam_patch_common_library

Barrel re-export of all common modules. Backends use a single use adam_patch_common_library to access all common types and constants.

Re-exported module	Key public symbols
adam_patch_bc_object	patch_bc_object, BC_DIRICHLET
adam_patch_common_object	patch_common_object
adam_patch_ic_object	patch_ic_object, IC_TYPE_GAUSS
adam_patch_io_object	patch_io_object
adam_patch_time_object	patch_time_object

License

PATCH is part of the ADAM framework, released under the GNU Lesser General Public License v3.0 (LGPLv3).

Copyright (C) Andrea Di Mascio, Federico Negro, Giacomo Rossi, Francesco Salvadore, Stefano Zaghi.