solver_stats_t Derived Type

   type, public :: solver_stats_t
      integer :: pressure_iterations = 0 !< Number of iterations taken by the most recent PCG solve.
      integer :: pressure_iterations_total = 0 !< Cumulative PCG iterations over all pressure solves.
      integer :: pressure_iterations_max = 0 !< Maximum PCG iterations used by any pressure solve.
      integer :: pressure_solve_count = 0 !< Number of pressure solves completed.
      real(rk) :: pressure_iterations_avg = zero !< Average PCG iterations per pressure solve.
      real(rk) :: pressure_residual = zero !< Final \(L_2\) residual norm of the Poisson system.
      real(rk) :: max_divergence = zero    !< Maximum local velocity divergence \(\nabla \cdot \mathbf{u}\) [1/s].
      real(rk) :: rms_divergence = zero    !< Root-mean-square divergence across the domain.
      real(rk) :: net_boundary_flux = zero !< Global mass flux imbalance across all boundaries [kg/s].
      real(rk) :: kinetic_energy = zero    !< Total domain kinetic energy \(\int \frac{1}{2} \rho |\mathbf{u}|^2 dV\) [J].
      real(rk) :: cfl = zero               !< Current Courant-Friedrichs-Lewy number.
      real(rk) :: wall_time = zero         !< Cumulative solver wall-clock time [s].
      real(rk) :: max_velocity = zero      !< Maximum velocity magnitude \(|\mathbf{u}|_{max}\) [m/s].
      real(rk) :: total_mass = zero        !< Total integrated mass in the domain [kg].
      real(rk) :: min_species_y = zero     !< Global minimum species mass fraction (diagnostic for boundedness).
   end type solver_stats_t