m_constants.fpp.f90

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# 1 "/home/runner/work/MFC/MFC/src/common/m_constants.fpp"
!>
!! @file
!! @brief Contains constant values used throughout the code(s).
 
!> @brief Compile-time constant parameters: default values, tolerances, and physical constants
module m_constants
 
    use m_precision_select
 
    character, parameter :: dflt_char = ' ' !< Default string value
 
    real(wp), parameter :: dflt_real = -1.e6_wp                !< Default real value
    real(wp), parameter :: sgm_eps = 1.e-16_wp               !< Segmentation tolerance
    real(wp), parameter :: chem_tolerance = 1.e-16_wp               !< Speed of Sound Tolerance in Chemistry
    real(wp), parameter :: small_alf = 1.e-11_wp                !< Small alf tolerance
    real(wp), parameter :: pi = 3.141592653589793_wp !< Pi
    real(wp), parameter :: verysmall = 1.e-12_wp              !< Very small number
    real(wp), parameter :: small_radius = 1.e-32_wp           !< Radius cutoff to avoid division by zero for 3D spherical harmonic patch (geometry 14)
 
    integer, parameter :: num_stcls_min = 5                       !< Minimum # of stencils
    integer, parameter :: path_len = 400                          !< Maximum path length
    integer, parameter :: name_len = 50                           !< Maximum name length
    integer, parameter :: dflt_int = -100                         !< Default integer value
    integer, parameter :: fourier_rings = 5                       !< Fourier filter ring limit
    integer, parameter :: num_fluids_max = 10                     !< Maximum number of fluids in the simulation
    integer, parameter :: num_probes_max = 10                     !< Maximum number of flow probes in the simulation
    integer, parameter :: num_patches_max = 1000
    integer, parameter :: num_bc_patches_max = 10
    integer, parameter :: max_2d_fourier_modes = 10 !< Max Fourier mode index for 2D modal patch (geometry 13)
    integer, parameter :: max_sph_harm_degree = 5   !< Max degree L for 3D spherical harmonic patch (geometry 14)
    integer, parameter :: pathlen_max = 400
    integer, parameter :: nnode = 4    !< Number of QBMM nodes
    integer, parameter :: dflt_num_igr_iters = 2 !< number of iterations for IGR elliptic solve
    integer, parameter :: dflt_num_igr_warm_start_iters = 50 !< default number of iterations for IGR elliptic solve
    real(wp), parameter :: dflt_alf_factor = 10._wp !< scaling factor for IGR alpha
    integer, parameter :: gp_layers = 3 !< Number of ghost point layers for IBM
    real(wp), parameter :: capillary_cutoff = 1.e-6 !< color function gradient magnitude at which to apply the surface tension fluxes
    real(wp), parameter :: acoustic_spatial_support_width = 2.5_wp !< Spatial support width of acoustic source, used in s_source_spatial
    real(wp), parameter :: dflt_vcfl_dt = 100._wp !< value of vcfl_dt when viscosity is off for computing adaptive timestep size
    real(wp), parameter :: broadband_spectral_level_constant = 20._wp !< The constant to scale the spectral level at the lower frequency bound
    real(wp), parameter :: broadband_spectral_level_growth_rate = 10._wp !< The spectral level constant to correct the magnitude at each frequency to ensure the source is overall broadband
 
    ! Reconstruction Types
    integer, parameter :: weno_type = 1 !< Using WENO for reconstruction type
    integer, parameter :: muscl_type = 2 !< Using MUSCL for reconstruction type
 
    ! Interface Compression
    real(wp), parameter :: dflt_ic_eps = 1e-4_wp !< Ensure compression is only applied to surface cells in THINC
    real(wp), parameter :: dflt_ic_beta = 1.6_wp !< Sharpness parameter's default value used in THINC
    real(wp), parameter :: moncon_cutoff = 1e-8_wp !< Monotonicity constraint's limiter to prevent extremas in THINC
 
    ! Chemistry
    real(wp), parameter :: dflt_t_guess = 1200._wp ! Default guess for temperature (when a previous value is not available)
 
    ! IBM+STL interpolation constants
    integer, parameter :: num_ray = 20 !< Default number of rays traced per cell
    real(wp), parameter :: ray_tracing_threshold = 0.9_wp !< Threshold above which the cell is marked as the model patch
    real(wp), parameter :: threshold_vector_zero = 1.e-10_wp !< Threshold to treat the component of a vector to be zero
    real(wp), parameter :: threshold_edge_zero = 1.e-10_wp !< Threshold to treat two edges to be overlapped
    real(wp), parameter :: initial_distance_buffer = 1.e12_wp !< Initialized levelset distance for the shortest path pair algorithm
 
    ! Lagrange bubbles constants
    integer, parameter :: mapcells = 3         !< Number of cells around the bubble where the smoothening function will have effect
    real(wp), parameter :: r_uni = 8314._wp    !< Universal gas constant - J/kmol/K
    integer, parameter :: lag_io_vars = 21 ! Number of variables per particle for MPI_IO
 
    ! Strang Splitting constants
    real(wp), parameter :: dflt_adap_dt_tol = 1.e-4_wp !< Default tolerance for adaptive step size
    integer, parameter :: dflt_adap_dt_max_iters = 100 !< Default max iteration for adaptive step size
 
    ! Constants of the algorithm described by Heirer, E. Hairer, S. P.Nørsett, G. Wanner, Solving Ordinary Differential Equations I, Chapter II.4
    ! to choose the initial time step size for the adaptive time stepping routine
    real(wp), parameter :: threshold_first_guess = 1.e-5_wp
    real(wp), parameter :: threshold_second_guess = 1.e-15_wp
    real(wp), parameter :: scale_first_guess = 1.e-3_wp
    real(wp), parameter :: scale_guess = 1.e-2_wp
    real(wp), parameter :: small_guess = 1.e-6_wp
 
    ! Relativity
    integer, parameter :: relativity_cons_to_prim_max_iter = 100
 
    ! Pseudo-random number generator
    integer, parameter :: modulus = 2**30 - 1
    integer, parameter :: multiplier = 1664525
    integer, parameter :: increment = 1013904223
    integer, parameter :: amplifier = 3**13
    real(wp), parameter :: decimal_trim = 1.e5_wp
 
    ! System constants
    integer, parameter :: case_file_error_code = 22
 
    ! Boundary condition enumeration
    ! Abbreviations
    !  CHAR - Characteristic
    !  NR   -  Non-reflecting
    !  SUB  - subsonic
    !  SUP  - supersonic
    !  FF   - Force-free
    !  CP   - Constant pressure
    integer, parameter :: bc_periodic = -1
    integer, parameter :: bc_reflective = -2
    integer, parameter :: bc_ghost_extrap = -3
    integer, parameter :: bc_riemann_extrap = -4
    integer, parameter :: bc_char_slip_wall = -5
    integer, parameter :: bc_char_nr_sub_buffer = -6
    integer, parameter :: bc_char_nr_sub_inflow = -7
    integer, parameter :: bc_char_nr_sub_outflow = -8
    integer, parameter :: bc_char_ff_sub_outflow = -9
    integer, parameter :: bc_char_cp_sub_outflow = -10
    integer, parameter :: bc_char_sup_inflow = -11
    integer, parameter :: bc_char_sup_outflow = -12
    integer, parameter :: bc_null = -13
    integer, parameter :: bc_axis = -14
    integer, parameter :: bc_slip_wall = -15
    integer, parameter :: bc_no_slip_wall = -16
    integer, parameter :: bc_dirichlet = -17
 
end module m_constants