Reads simulation parameters from a Fortran namelist file (default:
input.nml). If the file is absent, built-in Sod shock tube defaults
are used so the solver remains immediately runnable without any input file.
Namelist groups (all optional; missing groups keep their defaults):
&grid — spatial discretisation&time_ctrl — time-stepping parameters&physics — gas model (gamma)&schemes — algorithm selection strings (incl. MUSCL limiter)&initial_condition — Riemann problem left/right primitive states and BC types&output — result filename, diagnostic frequency, live snapshots&checkpoint — checkpoint write interval and restart pathExample usage in the driver: @code type(config_t) :: cfg call read_config('input.nml', cfg) @endcode
All runtime-configurable simulation parameters with Sod shock tube defaults.
| Type | Visibility | Attributes | Name | Initial | |||
|---|---|---|---|---|---|---|---|
| integer, | public | :: | n_cell | = | 500 | ||
| real(kind=wp), | public | :: | x_left | = | 0.0_wp | ||
| real(kind=wp), | public | :: | x_right | = | 1.0_wp | ||
| real(kind=wp), | public | :: | dt | = | 1.0e-4_wp | ||
| real(kind=wp), | public | :: | time_start | = | 0.0_wp | ||
| real(kind=wp), | public | :: | time_stop | = | 0.15_wp | ||
| real(kind=wp), | public | :: | cfl | = | 0.0_wp | ||
| logical, | public | :: | lapack_solver | = | .true. |
Set to .false. to use the built-in no-pivoting solver instead. Only relevant when time_scheme = 'beuler'. |
|
| real(kind=wp), | public | :: | gam | = | 1.4_wp | ||
| character(len=64), | public | :: | flux_scheme | = | 'lax_friedrichs' |
'lax_friedrichs' (default), 'steger_warming', 'van_leer', 'ausm_plus' |
|
| character(len=64), | public | :: | recon_scheme | = | 'weno5' | ||
| character(len=64), | public | :: | time_scheme | = | 'rk3' | ||
| character(len=8), | public | :: | char_proj | = | 'auto' |
'auto' (default) — enable per-scheme: on for weno5/weno5z/weno_cu6/weno7/ weno9/weno11/eno3/mp5/teno5, off otherwise. 'yes' — always apply eigensystem decomposition (more accurate for shocks, higher cost). 'no' — always skip eigensystem decomposition (faster; safe for scalar/smooth problems). |
|
| character(len=32), | public | :: | limiter | = | 'minmod' |
Valid values: 'minmod' (default), 'superbee', 'mc', 'van_leer', 'koren'. Ignored for all non-MUSCL reconstruction schemes. |
|
| logical, | public | :: | use_positivity_limiter | = | .false. |
When .true., reconstructed face states on the FDS path (AUSM+, HLL, HLLC, Roe) are scaled toward the adjacent cell average to ensure density and pressure remain non-negative. Ignored when a FVS flux scheme is active. |
|
| logical, | public | :: | use_hybrid_recon | = | .false. |
When .true., each face is classified smooth or non-smooth using the selected sensor (hybrid_sensor). Smooth faces use the linear (optimal-weight) WENO variant — same order as the primary scheme but without nonlinear dissipation. Non-smooth faces fall back to the full nonlinear primary reconstruction scheme. |
|
| character(len=32), | public | :: | hybrid_sensor | = | 'jameson' |
Valid values: 'jameson' — Jameson-Schmidt-Turkel pressure second-derivative sensor (JST 1981); physically motivated for compressible flows. Threshold ~ 0.1. 'density_gradient' — Normalised density jump across the face; cheap and robust. Threshold ~ 0.1. 'weno_beta' — Ratio max(β)/min(β) of WENO5 smoothness indicators; only meaningful for 5-point WENO-family schemes; falls back to 'density_gradient' otherwise. Threshold ~ 50. |
|
| real(kind=wp), | public | :: | hybrid_sensor_threshold | = | 0.1_wp |
Default 0.1 suits the 'jameson' and 'density_gradient' sensors. Use ~50 for 'weno_beta'. |
|
| character(len=64), | public | :: | problem_type | = | 'sod' |
Valid values: 'sod', 'shu_osher', 'smooth_wave', 'linear_advection', 'woodward_colella', 'lax', 'from_file', 'udf'. |
|
| character(len=256), | public | :: | ic_file | = | '' |
File must contain whitespace-separated columns: x rho u p (one line per grid point; same format as the solver output file). |
|
| logical, | public | :: | ic_interp | = | .true. |
When .false., a grid mismatch causes an error stop. |
|
| character(len=256), | public | :: | ic_udf_src | = | '' |
Used when problem_type = 'udf'. The solver compiles this file to a shared library at runtime (requires gfortran on PATH) and calls the subroutine to fill the initial state. See example/udf_sod.f90 for the required interface. |
|
| character(len=32), | public | :: | bc_left | = | 'dirichlet' |
Valid values: 'dirichlet' (default), 'inflow', 'outflow', 'reflecting', 'periodic', 'nonreflecting', 'supersonic_inlet', 'subsonic_inlet', 'supersonic_outlet', 'subsonic_outlet', 'neumann', 'neumann_gradient'. |
|
| character(len=32), | public | :: | bc_right | = | 'dirichlet' |
Valid values: 'dirichlet' (default), 'inflow', 'outflow', 'reflecting', 'periodic', 'nonreflecting', 'supersonic_inlet', 'subsonic_inlet', 'supersonic_outlet', 'subsonic_outlet', 'neumann', 'neumann_gradient'. |
|
| real(kind=wp), | public | :: | p_ref_left | = | 1.0_wp |
Used only when bc_left = 'nonreflecting'. |
|
| real(kind=wp), | public | :: | p_ref_right | = | 1.0_wp |
Used only when bc_right = 'nonreflecting'. |
|
| real(kind=wp), | public | :: | sigma_nrbc | = | 0.0_wp |
0 = fully non-reflecting; 1 = Dirichlet target pressure p_ref. See Thompson (1987), Poinsot & Lele (1992). |
|
| character(len=32), | public | :: | nrbc_mode | = | 'pressure' |
'pressure' (default) = isentropic pressure-relaxation (Thompson 1987). 'characteristic' = full LODI characteristic targeting (Poinsot & Lele 1992, Sec. 3); activates u_ref_, rho_ref_, sigma_nrbc_entropy. |
|
| real(kind=wp), | public | :: | u_ref_left | = | 0.0_wp |
Used only when bc_left = 'nonreflecting' and nrbc_mode = 'characteristic'. |
|
| real(kind=wp), | public | :: | u_ref_right | = | 0.0_wp |
Used only when bc_right = 'nonreflecting' and nrbc_mode = 'characteristic'. |
|
| real(kind=wp), | public | :: | rho_ref_left | = | 1.0_wp |
Used only when bc_left = 'nonreflecting' and nrbc_mode = 'characteristic'. |
|
| real(kind=wp), | public | :: | rho_ref_right | = | 1.0_wp |
Used only when bc_right = 'nonreflecting' and nrbc_mode = 'characteristic'. |
|
| real(kind=wp), | public | :: | sigma_nrbc_entropy | = | 0.0_wp |
0 = fully non-reflecting entropy wave (default); 1 = entropy wave driven to the rho_ref target. Active only when nrbc_mode = 'characteristic'. See Poinsot & Lele (1992), J. Comput. Phys. 101, Sec. 3. |
|
| real(kind=wp), | public | :: | p_stag_left | = | 1.0_wp |
Used only when bc_left = 'subsonic_inlet'. Derived from static conditions via p0 = p(1 + (gam-1)/2Ma^2)^(gam/(gam-1)). |
|
| real(kind=wp), | public | :: | rho_stag_left | = | 1.0_wp |
Used only when bc_left = 'subsonic_inlet'. Derived from static conditions via rho0 = rho(1 + (gam-1)/2Ma^2)^(1/(gam-1)). |
|
| real(kind=wp), | public | :: | p_stag_right | = | 1.0_wp |
Used only when bc_right = 'subsonic_inlet'. |
|
| real(kind=wp), | public | :: | rho_stag_right | = | 1.0_wp |
Used only when bc_right = 'subsonic_inlet'. |
|
| real(kind=wp), | public | :: | p_back_left | = | 1.0_wp |
Used only when bc_left = 'subsonic_outlet'. |
|
| real(kind=wp), | public | :: | p_back_right | = | 1.0_wp |
Used only when bc_right = 'subsonic_outlet'. |
|
| real(kind=wp), | public | :: | neumann_grad_left(3) | = | 0.0_wp |
Used only when bc_left = 'neumann_gradient'. Ghost state: q_ghost = q_wall + neumann_grad_left * dx. |
|
| real(kind=wp), | public | :: | neumann_grad_right(3) | = | 0.0_wp |
Used only when bc_right = 'neumann_gradient'. Ghost state: q_ghost = q_wall + neumann_grad_right * dx. |
|
| real(kind=wp), | public | :: | rho_left | = | 1.0_wp | ||
| real(kind=wp), | public | :: | u_left | = | 0.0_wp | ||
| real(kind=wp), | public | :: | p_left | = | 1.0_wp | ||
| real(kind=wp), | public | :: | rho_right | = | 0.125_wp | ||
| real(kind=wp), | public | :: | u_right | = | 0.0_wp | ||
| real(kind=wp), | public | :: | p_right | = | 0.1_wp | ||
| real(kind=wp), | public | :: | x_diaphragm | = | 0.5_wp | ||
| character(len=256), | public | :: | output_file | = | 'result.dat' | ||
| integer, | public | :: | print_freq | = | 50 | ||
| logical, | public | :: | do_timing | = | .false. |
Enable detailed wall-clock timing summary output (default .false.).
When .true., compute_resid() and the driver accumulate fine-grained
timing and print a performance table after the run. Lightweight
per-iteration |
|
| integer, | public | :: | verbosity | = | 3 |
Logger verbosity threshold (default 3 = LOGLVL_INFO).
0 = SILENT, 1 = ERROR, 2 = WARN, 3 = INFO, 4 = DEBUG.
See module |
|
| character(len=256), | public | :: | log_file | = | 'run.log' |
Log file path (default 'run.log'). Empty string disables file logging. |
|
| integer, | public | :: | snapshot_freq | = | 0 |
Write a live solution snapshot every N iterations (0 = disabled). The snapshot file is overwritten each time, so a GUI app can watch it with inotify/kqueue. Format matches result.dat with a leading comment line: "# iter=NNN t=T". |
|
| character(len=256), | public | :: | snapshot_file | = | 'snapshot.dat' |
Path for the live snapshot file (default 'snapshot.dat'). |
|
| integer, | public | :: | checkpoint_freq | = | 0 |
Write a checkpoint every N iterations (0 = disabled).
Checkpoint files are named ' |
|
| character(len=256), | public | :: | checkpoint_file | = | 'checkpoint' |
Base name for checkpoint files (default 'checkpoint'). |
|
| character(len=256), | public | :: | restart_file | = | '' |
Path to a checkpoint file to resume from (empty = fresh start). When set, the IC is skipped and iter/t are loaded from the checkpoint. |
Return a left-trimmed, lowercased copy of value.
Pure: has no side effects; suitable for use in constant expressions.
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| character(len=*), | intent(in) | :: | value |
Read simulation parameters from a namelist file.
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| character(len=*), | intent(in) | :: | filename |
Path to the namelist input file. |
||
| type(config_t), | intent(out) | :: | cfg |
Populated configuration object. |
||
| logical, | intent(out), | optional | :: | is_ok | ||
| character(len=*), | intent(out), | optional | :: | message |
Validate that all namelist parameters are physically and numerically sensible.
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| type(config_t), | intent(inout) | :: | cfg |
Configuration to validate (normalised in-place). |
||
| logical, | intent(out), | optional | :: | is_valid |
|
|
| character(len=*), | intent(out), | optional | :: | message |
Human-readable description of the first violation, or |
Lowercase all scheme-selection and option string fields in cfg.
Called automatically by validate_config before any comparisons so that
namelist values are accepted regardless of the case supplied by the user.
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| type(config_t), | intent(inout) | :: | cfg |