NASTO — Common

Backend-independent physics, configuration, and I/O layer for all NASTO solvers.

The common/ directory provides the objects shared by every NASTO backend (CPU, NVF, FNL, GMP). It covers the full simulation lifecycle — configuration parsing, equation of state, initial and boundary conditions, time-step control, and I/O — without containing any backend-specific compute kernels.

Module overview

Source file	Module	Type	Role
`adam_nasto_parameters.F90`	`adam_nasto_parameters`	—	Global parameter placeholder
`adam_nasto_common_object.F90`	`adam_nasto_common_object`	`nasto_common_object`	Central orchestrator; extended by every backend
`adam_nasto_physics_object.F90`	`adam_nasto_physics_object`	`nasto_physics_object`	Species count and variable-index management
`adam_nasto_eos_object.F90`	`adam_nasto_eos_object`	`nasto_eos_object`	Ideal-gas equation of state per species
`adam_nasto_bc_object.F90`	`adam_nasto_bc_object`	`nasto_bc_object`	Boundary condition types and inflow data
`adam_nasto_ic_object.F90`	`adam_nasto_ic_object`	`nasto_ic_object`	Initial condition setup (uniform, vortex, Riemann)
`adam_nasto_io_object.F90`	`adam_nasto_io_object`	`nasto_io_object`	Output frequency, restart, residual monitoring
`adam_nasto_time_object.F90`	`adam_nasto_time_object`	`nasto_time_object`	CFL time-step control and termination criteria
`adam_nasto_common_library.F90`	`adam_nasto_common_library`	—	Barrel re-export of all modules above

Object hierarchy

`nasto_common_object`

The top-level base class. Every backend object (nasto_cpu_object, nasto_nvf_object, etc.) extends this type, inheriting all handlers and grid/field references without duplicating configuration logic.

Data members

ADAM SDK objects (aggregated, not inherited):

Member	Type	Purpose
`mpih`	`mpih_object`	MPI communication handler
`adam`	`adam_object`	Top-level ADAM framework
`field`	`field_object*`	5D field array container
`grid`	`grid_object*`	Block-structured grid geometry
`amr`	`amr_object`	AMR marker and refinement handler
`ib`	`ib_object`	Immersed boundary method
`slices`	`slices_object`	In-situ slice output
`rk`	`rk_object`	Runge-Kutta temporal integrator
`weno`	`weno_object`	WENO reconstruction

NASTO handlers:

Member	Type	Purpose
`io`	`nasto_io_object`	Output and restart control
`physics`	`nasto_physics_object`	Species and thermodynamics
`ic`	`nasto_ic_object`	Initial condition setup
`bc`	`nasto_bc_object`	Boundary conditions
`time`	`nasto_time_object`	Time-step and termination

Field arrays (allocated with ghost cells):

fortran

real(R8P), allocatable :: q    (nv,     1-ngc:ni+ngc, 1-ngc:nj+ngc, 1-ngc:nk+ngc, nb)
real(R8P), allocatable :: q_aux(nv_aux, 1-ngc:ni+ngc, 1-ngc:nj+ngc, 1-ngc:nk+ngc, nb)

q holds conservative variables; q_aux holds primitive/auxiliary variables (density, velocity components, pressure, temperature, etc.).

Methods

Procedure	Purpose
`allocate_common()`	Allocates `q` and `q_aux` with correct ghost-cell bounds
`initialize_common()`	Full startup sequence: MPI → IO → physics → grid → AMR → fields → IC → BC → time → WENO → IB

`nasto_physics_object`

Manages the number of fluid species and the mapping between species and conservative-variable indices.

Data members

Member	Type	Default	Description
`ns`	`I4P`	1	Number of fluid species
`nv`	`I4P`	5	Conservative variables = `ns + 4` (momentum + energy)
`nv_aux`	`I4P`	9	Auxiliary variables = `ns + 8`
`np`	`I4P`	5	1D primitive variables = `ns + 4`
`eos(:)`	`nasto_eos_object`	—	EOS model for each species `[1:ns]`

Variable index offsets (module-level, computed after initialize()):

Index	Meaning
`IR = ns + 1`	Bulk density in `q_aux`
`IU = ns + 2`	x-velocity
`IV = ns + 3`	y-velocity
`IW = ns + 4`	z-velocity
`IG = ns + 5`	Heat capacity ratio γ
`IP = ns + 6`	Pressure

Methods

Procedure	Notes
`initialize()`	Reads `ns` from INI; allocates `eos(1:ns)`; updates index offsets
`conservative2primitive()`	Pure: `(ρs, ρu, ρv, ρw, ρE) → (s, u, v, w, ρ, p, γ)`
`primitive2conservative()`	Pure: inverse conversion
`description()`	Formatted summary string

INI configuration

ini

[physics]
  ns = 1          ! number of fluid species

`nasto_eos_object`

Ideal-gas equation of state for a single fluid species. Stores primary thermodynamic properties and pre-computes derived combinations for efficiency.

Data members

Member	Type	Description
`cp`	`R8P`	Specific heat at constant pressure (J/kg·K)
`cv`	`R8P`	Specific heat at constant volume (J/kg·K)
`g`	`R8P`	Heat capacity ratio γ = cp/cv
`R`	`R8P`	Gas constant = cp − cv (J/kg·K)
`mu`	`R8P`	Dynamic viscosity (Pa·s)
`kd`	`R8P`	Thermal diffusivity (W/m·K)
`dha`	`R8P`	Enthalpy of formation (J/kg)
`gm1`	`R8P`	γ − 1 (pre-computed)
`gp1`	`R8P`	γ + 1 (pre-computed)
`delta`	`R8P`	(γ − 1)/2
`eta`	`R8P`	2γ/(γ − 1)

Methods

Elemental state functions (vectorise over arrays):

Procedure	Returns
`pressure(ρ, e)`	$p = (γ - 1) ρ e$
`density(p, c)`	$ρ = γ p / c^{2}$
`speed_of_sound(ρ, p)`	$c = \sqrt{γ p / ρ}$
`temperature(ρ, p)`	$T = p / (ρ R)$
`internal_energy(ρ, p)`	$e = p / [(γ - 1) ρ]$
`total_energy(ρ, u, v, w, p)`	$E = e + \frac{1}{2} (u^{2} + v^{2} + w^{2})$
`total_entalpy(ρ, u, v, w, p)`	$H = E + p / ρ$

Other methods:

Procedure	Purpose
`compute_derivate()`	Derives `gm1`, `gp1`, `delta`, `eta` from `cp`/`cv`
`conservative2primitive()`	Single-species conversion
`load_from_file()`	Reads properties from INI
`save_into_file()`	Writes properties back to INI
`destroy()`	Resets to default state

INI configuration

Section name: physics_specie_N where N is the species index (1-based).

ini

[physics_specie_1]
  cp  = 1004.5      ! J/kg·K
  cv  = 717.5       ! J/kg·K
  mu  = 1.8e-5      ! Pa·s
  kd  = 0.026       ! W/m·K
  dha = 0.0         ! J/kg  (enthalpy of formation)

`nasto_bc_object`

Stores the boundary condition type for each of the six domain faces and the prescribed primitive-variable state for inflow boundaries.

Boundary condition types

Constant	Value	Description
`BC_EXTRAPOLATION`	1	Zero-gradient extrapolation (outflow)
`BC_INFLOW`	2	Supersonic inflow with prescribed (ρ, u, v, w, p)
`BC_WALL_INVISCID`	3	Slip wall — normal velocity set to zero

Face ordering in bc_type(6): x_min, x_max, y_min, y_max, z_min, z_max.

INI configuration

ini

[bc_x_min]
  type = inflow
  r = 1.225       ! density (kg/m³)
  u = 340.0       ! x-velocity (m/s)
  v = 0.0
  w = 0.0
  p = 101325.0    ! pressure (Pa)
  s = 1           ! species index

[bc_x_max]
  type = extrapolation

[bc_y_min]
  type = wall-inviscid

[bc_y_max]
  type = extrapolation

[bc_z_min]
  type = periodic

[bc_z_max]
  type = periodic

`nasto_ic_object`

Sets the initial field q across all AMR blocks. Supports three analytical configurations and a flexible multi-region domain decomposition.

Initial condition types

Type string	Description
`uniform`	Uniform state everywhere; optional random velocity perturbation
`isentropic-vortex`	Lamb-Oseen isentropic vortex superposed on a background flow
`riemann-problem`	Piecewise-constant regions defined by axis-aligned bounding boxes

Data members

Member	Description
`ic_type`	Selected IC type string
`regions_number`	Number of spatial regions
`q(6, regions_number)`	Primitive state per region: (ρ, u, v, w, p, species)
`emin(3, regions_number)`	Min corner (x, y, z) of each region bounding box
`emax(3, regions_number)`	Max corner (x, y, z) of each region bounding box
`amr_iterations`	AMR refinement passes applied after IC setup

INI configuration

ini

[initial_conditions]
  type            = riemann-problem
  regions_number  = 2
  amr_iterations  = 3

[initial_conditions_region_1]
  r = 1.0   u = 0.0   v = 0.0   w = 0.0   p = 1.0   s = 1
  emin_x = 0.0   emin_y = 0.0   emin_z = 0.0
  emax_x = 10.0  emax_y = 20.0  emax_z = 20.0

[initial_conditions_region_2]
  r = 0.125   u = 0.0   v = 0.0   w = 0.0   p = 0.1   s = 1
  emin_x = 10.0  emin_y = 0.0   emin_z = 0.0
  emax_x = 20.0  emax_y = 20.0  emax_z = 20.0

`nasto_io_object`

Controls output scheduling, restart checkpointing, and residual monitoring.

Data members

Member	Type	Default	Description
`output_basename`	`character`	—	Base filename for HDF5 snapshots
`it_save`	`I4P`	100	Output frequency (iterations)
`restart`	`logical`	`.false.`	Enable restart from checkpoint
`restart_basename`	`character`	—	Base filename for restart files
`restart_save`	`I4P`	100	Restart checkpoint frequency
`residuals_save`	`I4P`	10	Residuals file write frequency
`save_memory_status`	`logical`	`.false.`	Log memory usage during allocation

Methods

Procedure	Purpose
`initialize()`	Creates FiNeR parser; loads all IO parameters
`open_file_residuals()`	Opens residuals file; writes column header
`save_residuals()`	Appends iteration, time, block count, and field norms
`close_file_residuals()`	Closes residuals file unit
`description()`	Pure: formatted configuration summary

INI configuration

ini

[IO]
  output_basename    = nasto_out
  it_save            = 100
  restart            = .false.
  restart_basename   = nasto_rst
  restart_save       = 500
  residuals_save     = 10
  save_memory_status = .false.

`nasto_time_object`

Governs temporal integration: CFL-based time-step selection, iteration counting, and simulation termination.

Data members

Member	Type	Default	Description
`it_max`	`I4P`	−1	Max iterations; ≤ 0 means use `time_max` instead
`time_max`	`R8P`	1.0	Max physical time (s)
`CFL`	`R8P`	0.3	Courant–Friedrichs–Lewy number
`it`	`I4P`	0	Current iteration counter
`time`	`R8P`	0.0	Current physical time
`dt`	`R8P`	0.0001	Current time step (updated each iteration)

Termination logic

`it_max`	Stopping criterion
≤ 0	`time ≥ time_max`
> 0	`it ≥ it_max`

Output is also forced at the final iteration regardless of it_save spacing.

Methods

Procedure	Purpose
`initialize()`	Loads time parameters from INI
`is_to_save() → logical`	Returns `.true.` when output should be written
`print_progress()`	Prints iteration, time, dt, and % completion
`description()`	Pure: formatted configuration summary

INI configuration

ini

[time]
  it_max   = -1       ! use time_max as stopping criterion
  time_max = 10.0     ! seconds
  CFL      = 0.8

`adam_nasto_common_library`

A barrel re-export module: use adam_nasto_common_library brings every module listed in the overview table into scope with a single statement. Backend objects use this as their sole import from common/.

Copyrights

NASTO 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.

NASTO — Common ​

Module overview ​

Object hierarchy ​

nasto_common_object ​

Data members ​

Methods ​

nasto_physics_object ​

Data members ​

Methods ​

INI configuration ​

nasto_eos_object ​

Data members ​

Methods ​

INI configuration ​

nasto_bc_object ​

Boundary condition types ​

INI configuration ​

nasto_ic_object ​

Initial condition types ​

Data members ​

INI configuration ​

nasto_io_object ​

Data members ​

Methods ​

INI configuration ​

nasto_time_object ​

Data members ​

Termination logic ​

Methods ​

INI configuration ​

adam_nasto_common_library ​

Copyrights ​

NASTO — Common

Module overview

Object hierarchy

`nasto_common_object`

Data members

Methods

`nasto_physics_object`

Data members

Methods

INI configuration

`nasto_eos_object`

Data members

Methods

INI configuration

`nasto_bc_object`

Boundary condition types

INI configuration

`nasto_ic_object`

Initial condition types

Data members

INI configuration

`nasto_io_object`

Data members

Methods

INI configuration

`nasto_time_object`

Data members

Termination logic

Methods

INI configuration

`adam_nasto_common_library`

Copyrights