CHASE — Common

Backend-independent modules shared by all CHASE backends.

The common/ directory contains the base object and all CHASE-specific handler types. Every backend extends chase_common_object and reuses these modules unchanged.

Source layout

Source file	Module	Role
`adam_chase_common_object.F90`	`adam_chase_common_object`	Base object — ADAM SDK + CHASE handler composition
`adam_chase_physics_object.F90`	`adam_chase_physics_object`	Fluid physics — EOS, variable layout, flux procedures
`adam_chase_parameters.F90`	`adam_chase_parameters`	Physical constants and eigenvector matrices
`adam_chase_bc_object.F90`	`adam_chase_bc_object`	Boundary conditions handler
`adam_chase_ic_object.F90`	`adam_chase_ic_object`	Initial conditions handler
`adam_chase_io_object.F90`	`adam_chase_io_object`	IO handler — XH5F output, restart, residuals
`adam_chase_time_object.F90`	`adam_chase_time_object`	Time state and integration parameters
`adam_chase_riemann_library.F90`	`adam_chase_riemann_library`	Riemann solvers and Maxwell flux functions
`adam_chase_common_library.F90`	`adam_chase_common_library`	Barrel re-export of all common modules

`chase_common_object`

Non-extending base type that aggregates all ADAM SDK objects and CHASE-specific handlers. Backend objects (e.g. chase_cpu_object) extend this type and provide the numerical methods.

Composition

Data members

Member	Type	Description
`mpih`	`mpih_object`	MPI handler
`adam`	`adam_object`	ADAM SDK — grid, tree, field, AMR, IO
`field`	`field_object*`	Field variable storage and ghost-cell maps (pointer into `adam`)
`grid`	`grid_object*`	Structured block grid (pointer into `adam`)
`amr`	`amr_object`	AMR marker handler
`ib`	`ib_object`	Immersed Boundary handler
`slices`	`slices_object`	Slice sampling for scheduled output
`rk`	`rk_object`	Runge-Kutta integrator
`weno`	`weno_object`	WENO reconstructor
`io`	`chase_io_object`	IO configuration and file handles
`physics`	`chase_physics_object`	EOS and WENO projection basis
`ic`	`chase_ic_object`	Initial conditions
`bc`	`chase_bc_object`	Boundary conditions
`time`	`chase_time_object`	Time state and parameters
`ngc, ni, nj, nk, nb`	`integer*`	Grid dimension pointers
`blocks_number, nv, nv_aux`	`integer*`	Size pointers
`q`	`real(R8P)(nv, 1-ngc:ni+ngc, …, nb)`	Conservative variables
`q_aux`	`real(R8P)(nv_aux, 1-ngc:ni+ngc, …, nb)`	Auxiliary variables
`q_name`	`character(2)(nv)`	Variable names: `r ru rv rw rE`

`initialize_common(field, filename, …)`

Initialisation sequence:

mpih%initialize         ! MPI init
io%initialize           ! parse INI file
bc%initialize           ! read BC config
physics%initialize      ! EOS + WENO basis
adam%grid%initialize    ! build structured grid
adam%compute_blocks_number
adam%initialize         ! tree + maps + field
adam%refine_uniform     ! initial uniform refinement
adam%prune              ! tree pruning
amr%initialize
time%initialize
ic%initialize
ib%initialize
slices%initialize
rk%initialize
weno%initialize
allocate_common         ! allocate q_aux
adam%io%initialize      ! register output variables

Output variable names registered with ADAM IO: r_a u_a v_a w_a p_a a_a T_a E_a H_a Rfa g_a.

`chase_physics_object`

Encapsulates the ideal-gas equation of state and the WENO reconstruction basis selection. Also exports three pure elemental procedures used directly in the compute kernel loop.

Variable layout

Array	Index	Symbol	Description
`q` (conservative)	1	$ρ$	Density
	2	$ρ u$	x-momentum
	3	$ρ v$	y-momentum
	4	$ρ w$	z-momentum
	5	$ρ E$	Total energy
`q_aux` (auxiliary)	1	$ρ$	Density
	2	$u$	x-velocity
	3	$v$	y-velocity
	4	$w$	z-velocity
	5	$p$	Pressure
	6	$T$	Temperature
	7	$E$	Total specific energy
	8	$H$	Total specific enthalpy
	9	$a$	Speed of sound
	10	$R_{f} = c_{p} - c_{v}$	Fluid constant
	11	$γ = c_{p} / c_{v}$	Specific heats ratio

Named index constants (e.g. VAR_R=1, VAR_RU=2, …, VAR_G=11) are exported as public parameters.

Key data members

Member	Default	Description
`nv`	5	Conservative variable count
`nv_aux`	11	Auxiliary variable count
`eos`	—	`eos_ic_object` — ideal-gas: R, cv, g, mu, delta, gm1
`weno_rec_var`	—	`'CONSERVATIVE'` or `'CHARACTERISTICS'`
`erw`, `elw`	—	Right/left eigenvector matrix pointers for WENO projection

WENO reconstruction basis (INI section [physics], key weno_rec_var):

Value	Matrix used	Description
`CONSERVATIVE`	`IERL` (identity, 6×6×3)	Reconstruct conservative variables directly
`CHARACTERISTICS`	`ER` / `EL` (6×6×3)	Project to characteristics before reconstruction

Module-level procedures

Procedure	Description
`compute_auxiliary(cv, Rf, g, conservative, auxiliary)`	Single-cell conservative → auxiliary; derives $p = R_{f} ρ T$ , $a = \sqrt{γ R_{f} T}$ , $H = E + R_{f} T$
`compute_conservative(auxiliary, conservative)`	Single-cell auxiliary → conservative: $ρ E = ρ H - p$
`compute_fluxes_conservative(sir, auxiliary, fluxes)`	Single-cell Euler flux vector in direction `sir`; $F_{1} = ρ u \cdot \hat{s}$ , $F_{5} = F_{1} H$

`adam_chase_parameters`

Global physical constants and precomputed eigenvector matrices. All symbols are public module-level entities.

Physical constants

Parameter	Value	Description
`NV_MAX`	11	Maximum variable count for static array sizing
`MU0`	1.256637×10⁻⁶	Vacuum magnetic permeability $μ_{0}$ (H m⁻¹)
`EPS0`	8.854187×10⁻¹²	Vacuum permittivity $ε_{0}$ (F m⁻¹)
`C0`	$1 / \sqrt{μ_{0} ε_{0}}$	Vacuum speed of light $c_{0}$ (m s⁻¹)
`PI`	3.14159…	$π$
`E_CHARGE`	−1.6×10⁻¹⁹	Electron charge (C)
`E_MASS`	9.11×10⁻³¹	Electron mass (kg)
`K_B`	1.380649×10⁻²³	Boltzmann constant (J K⁻¹)

Eigenvector matrices

Pre-built for characteristic-based WENO projection on a 6-component system.

Symbol	Shape	Description
`EV(6)`	`[0,0,c₀,c₀,−c₀,−c₀]`	Eigenvalues (electromagnetic wave speeds)
`ER(6,6,3)`	6×6×3	Right eigenvectors per direction
`EL(6,6,3)`	6×6×3	Left eigenvectors per direction
`IEV(6)`	`[1,1,1,1,1,1]`	Identity eigenvalues
`IERL(6,6,3)`	6×6×3	Identity eigenvectors (no projection)

`chase_bc_object`

Reads and stores boundary conditions for all 6 domain faces.

BC types

Constant	Value	INI keyword	Description
`BC_EXTRAPOLATION`	1	`extrapolation`	Zero-order extrapolation into ghost cells
`BC_INFLOW`	2	`inflow`	Supersonic inflow — prescribed primitive state
`BC_WALL_INVISCID`	3	`wall-inviscid`	Slip wall (normal velocity reflected)

INI configuration

One section per face: [bc_x_min], [bc_x_max], [bc_y_min], [bc_y_max], [bc_z_min], [bc_z_max].

ini

[bc_x_min]
type = extrapolation

[bc_x_max]
type = inflow
r  = 1.0     ; density
u  = 2.0     ; x-velocity
v  = 0.0     ; y-velocity
w  = 0.0     ; z-velocity
p  = 1.0     ; pressure
s  = 0.0     ; perturbation seed

[bc_y_min]
type = wall-inviscid

The inflow state q(:, face) stores (r, u, v, w, p, s) — 6 values per face. s is a perturbation amplitude used by the IC module.

Data members

Member	Description
`bc_type(6)`	BC type integer per face
`q(6, 6)`	Primitive state `(r,u,v,w,p,s)` for each face

`chase_ic_object`

Sets initial conditions at simulation start and after each AMR adaptation pass.

IC types

Constant	INI keyword	Description
`IC_TYPE_UNIFORM`	`uniform`	Constant $(ρ, u, v, w, p)$ with optional random velocity perturbation $δ u \in [0, q_{6}]$
`IC_TYPE_IVORTEX`	`isentropic-vortex`	Analytical isentropic vortex; $q_{6}$ = radius, `emin(x,y)` = centre coordinates
`IC_TYPE_RP`	`riemann-problem`	Piecewise constant regions; each box defined by `[emin, emax]` in 3D

INI configuration

ini

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

[initial_conditions_region_1]
r      = 1.0
u      = 0.0
v      = 0.0
w      = 0.0
p      = 1.0
s      = 0.0
emin_x = -1.0  ;  emin_y = -1.0  ;  emin_z = -1.0
emax_x =  0.0  ;  emax_y =  1.0  ;  emax_z =  1.0

[initial_conditions_region_2]
r      = 0.125
u      = 0.0
; ...
emin_x =  0.0  ;  ...  ;  emax_x = 1.0  ;  ...

amr_iterations controls how many AMR + IC cycles to run before the final initial condition is applied on the converged grid.

`chase_io_object`

Manages file I/O scheduling, file handles, and residuals output.

Data members

INI option (`[IO]`)	Default	Description
`it_save`	100	Main XH5F snapshot frequency (every N steps)
`output_basename`	—	Basename for XH5F output files
`restart`	`.false.`	Enable restart from checkpoint
`restart_basename`	—	Basename for restart files
`restart_save`	100	Restart checkpoint frequency (every N steps)
`save_memory_status`	`.false.`	Log memory usage during allocation
`residuals_save`	10	Residuals norm output frequency (every N steps)

Methods

Procedure	Description
`open_file_residuals`	Opens residuals text file at `output_basename.res`
`close_file_residuals`	Closes the residuals file
`save_residuals(it, time, blocks_number, residuals)`	Appends one line: step, time, per-variable L2 norms

`chase_time_object`

Tracks simulation time and provides the termination check.

Data members

INI option (`[time]`)	Default	Description
`it_max`	−1	Maximum time steps (−1 = ignore)
`time_max`	1.0	Maximum simulation time
`CFL`	0.3	CFL stability coefficient
`it`	0	Current time step counter
`time`	0.0	Current simulation time
`dt`	0.0001	Current time step (updated each step)

Termination criteria

is_to_save(it_save) returns .true. when any of:

Criterion	Condition
Periodic output	`mod(it, it_save) == 0`
Step limit	`it_max > 0` and `it >= it_max`
Time limit	`it_max <= 0` and `time >= time_max`

`adam_chase_riemann_library`

Riemann solver library for Maxwell's equations and related flux functions.

Public procedures

Procedure	Description
`compute_riemann_maxwell_llf(sir, nv, q1, q4, f [,lmax])`	LLF (Rusanov) solver; wave speed fixed at $c_{0} = 1 / \sqrt{μ_{0} ε_{0}}$
`compute_riemann_maxwell_hll(sir, nv, q1, q4, f [,lmax, lmin])`	HLL solver; $λ_{max} = + c_{0}$ , $λ_{min} = - c_{0}$
`compute_convective_fluxes_maxwell(sir, q, f)`	Maxwell flux vector in direction `sir`
`compute_convective_fluxes_maxwell_div_d(sir, q, f)`	Maxwell flux with $\nabla \cdot D$ divergence cleaning
`compute_convective_fluxes_maxwell_div_d_b(sir, q, f)`	Maxwell flux with $\nabla \cdot D$ and $\nabla \cdot B$ cleaning

Note: This module is not included in adam_chase_common_library and must be used explicitly by any backend that requires it.

`adam_chase_common_library`

Barrel re-export module. A single use adam_chase_common_library brings all common handler modules into scope:

fortran

use adam_chase_bc_object
use adam_chase_common_object
use adam_chase_ic_object
use adam_chase_io_object
use adam_chase_parameters
use adam_chase_physics_object
use adam_chase_time_object

adam_chase_riemann_library is intentionally excluded — backends use it directly when needed.

Copyrights

CHASE 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.

CHASE — Common ​

Source layout ​

chase_common_object ​

Composition ​

Data members ​

initialize_common(field, filename, …) ​

chase_physics_object ​

Variable layout ​

Key data members ​

Module-level procedures ​

adam_chase_parameters ​

Physical constants ​

Eigenvector matrices ​

chase_bc_object ​

BC types ​

INI configuration ​

Data members ​

chase_ic_object ​

IC types ​

INI configuration ​

chase_io_object ​

Data members ​

Methods ​

chase_time_object ​

Data members ​

Termination criteria ​

adam_chase_riemann_library ​

Public procedures ​

adam_chase_common_library ​

Copyrights ​

CHASE — Common

Source layout

`chase_common_object`

Composition

Data members

`initialize_common(field, filename, …)`

`chase_physics_object`

Variable layout

Key data members

Module-level procedures

`adam_chase_parameters`

Physical constants

Eigenvector matrices

`chase_bc_object`

BC types

INI configuration

Data members

`chase_ic_object`

IC types

INI configuration

`chase_io_object`

Data members

Methods

`chase_time_object`

Data members

Termination criteria

`adam_chase_riemann_library`

Public procedures

`adam_chase_common_library`

Copyrights