write_diagnostics_header Subroutine

   subroutine write_diagnostics_header(params, flow)
      type(case_params_t), intent(in) :: params
      type(flow_mpi_t), intent(in) :: flow

      integer :: unit_id
      character(len=path_len + 32) :: filename

      if (flow%rank /= 0 .or. .not. params%write_diagnostics) return

      filename = trim(params%output_dir)//'/diagnostics/diagnostics.csv'
      open(newunit=unit_id, file=trim(filename), status='replace', action='write')

      write(unit_id,'(a)') 'step,time,dt,max_divergence,rms_divergence,net_boundary_flux,'// &
                           'kinetic_energy,pressure_iterations,pressure_iterations_total,'// &
                           'pressure_iterations_max,pressure_iterations_avg,pressure_solve_count,'// &
                           'pressure_residual,pressure_residual_abs,cfl,wall_time,max_velocity,total_mass,min_species_y'

      close(unit_id)
   end subroutine write_diagnostics_header