mfix_pic_mod.f

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!vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv!
!                                                                      !
!  Module: MFIX_PIC                                                    !
!  Purpose: MP-PIC related data                                        !
!  Author: R. Garg                                                     !
!                                                                      !
!^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^!
      MODULE mfix_pic

      use param, only: dim_m
!......................................................................!

! flag for turning on MP-PIC method
      LOGICAL :: mppic

      DOUBLE PRECISION :: psfac_fric_pic
      DOUBLE PRECISION :: fric_exp_pic
      DOUBLE PRECISION :: fric_non_sing_fac

      LOGICAL :: mppic_solid_stress_snider
      LOGICAL :: mppic_corr_volfrac
      INTEGER :: iter_vol_frac_corr

! force to solids pressure gradient
      DOUBLE PRECISION, DIMENSION(:,:), ALLOCATABLE :: ps_force_pic

! avg solid velocity at particle position (used for MP-PIC)
      DOUBLE PRECISION, DIMENSION(:,:), ALLOCATABLE :: avgsolvel_p

! EP_g interpolated at particle position (used for MP-PIC)
      DOUBLE PRECISION, DIMENSION(:), ALLOCATABLE :: epg_p

! to initially seed the particles based on constant number of
! particles per cell or constant statistical weight of each particle
! number of particles per cell for the case of CONSTANTNPC
      LOGICAL :: mppic_constantnpc, mppic_constantwt

      INTEGER npc_pic(dim_m)

! coefficeient of restituion used in MPPIC case in the
! frictional regime
      DOUBLE PRECISION :: mppic_coeff_en1, mppic_coeff_en2
      DOUBLE PRECISION :: mppic_coeff_en_wall, mppic_coeff_et_wall

! statistical weight or number of real particles per computational
! particle for the case of CONSTANTWT
      DOUBLE PRECISION statwt_pic(dim_m)

! # of computational particles for the entire grid
! keep it double precision for inlow BC
      DOUBLE PRECISION , DIMENSION(:,:), ALLOCATABLE :: cnp_array

! Statistical weight of each particle
      DOUBLE PRECISION, DIMENSION(:), ALLOCATABLE :: des_stat_wt

!     logical variable to decide if special treatment is needed or not
!     in the direction of gravity in the frictional stress tensor
      LOGICAL :: mppic_grav_treatment

! Particle response time scale for each phase
      DOUBLE PRECISION :: des_tau_p(dim_m)

! The maximum dt for point particles based on particle response time
! (taup) and cfl. See cfassign for its computation
      DOUBLE PRECISION :: dtpic_max

! CFL value for point-particles that is used to control DTSOLID
! DTPP_CFL, dt for point-particles based on user specified CFL_PP
! and maximum velocity of particles
      DOUBLE PRECISION cfl_pic, dtpic_cfl, dtpic_taup

      DOUBLE PRECISION :: dtsolid_orig
! solid pressure gradient
      DOUBLE PRECISION, DIMENSION(:,:), ALLOCATABLE :: ps_grad

! flag to turn on implicit treatment of drag force term in particle
! trajectory evolution equation
      LOGICAL mppic_pdrag_implicit

! Solids pressure as a result of granular motion
      DOUBLE PRECISION, DIMENSION(:, :), ALLOCATABLE :: pic_p_s
!Face centered u-velocity required by PIC model.
      DOUBLE PRECISION, DIMENSION(:,:), ALLOCATABLE :: pic_u_s
! Face centered v-velocity required by PIC model. Not using the U_s arrays anymore
      DOUBLE PRECISION, DIMENSION(:,:), ALLOCATABLE :: pic_v_s
! Face centered z-velocity required by PIC model. Not using the U_s arrays anymore
      DOUBLE PRECISION, DIMENSION(:,:), ALLOCATABLE :: pic_w_s

! A run time flag to report minimum value of gas voidage
      LOGICAL :: pic_report_min_epg

      END MODULE mfix_pic