more revisions

Author: wpbonelli

src/Solution/ParticleTracker/MethodDis.f90

@@ -192,18 +192,22 @@ subroutine load_particle(this, cell, particle)
 
     select type (dis => this%fmi%dis)
     type is (DisType)
-      ! compute and set reduced/user node numbers and layer
+      ! compute reduced/user node numbers and layer
       inface = particle%iboundary(2)
       inbr = cell%defn%facenbr(inface)
       idiag = this%fmi%dis%con%ia(cell%defn%icell)
       ipos = idiag + inbr
       ic = dis%con%ja(ipos)
+      icu = dis%get_nodeuser(ic)
+      call get_ijk(icu, dis%nrow, dis%ncol, dis%nlay, &
+                   irow, icol, ilay)
 
-      ! if returning to immediately previous cell
-      ! through its bottom, we've entered a cycle
-      ! as can occur e.g. in the bottom of wells.
-      ! terminate in the previous cell.
-      if (ic == particle%icp .and. inface == 7) then
+      ! if returning to a cell through the bottom
+      ! face after previously leaving it through  
+      ! that same face, we've entered a cycle
+      ! as can occur e.g. in wells. terminate
+      ! in the previous cell.
+      if (ic == particle%icp .and. inface == 7 .and. ilay < particle%ilay) then
         particle%advancing = .false.
         particle%idomain(2) = particle%icp
         particle%istatus = 2
@@ -215,9 +219,7 @@ subroutine load_particle(this, cell, particle)
         particle%izp = particle%izone
       end if
 
-      icu = dis%get_nodeuser(ic)
-      call get_ijk(icu, dis%nrow, dis%ncol, dis%nlay, &
-                   irow, icol, ilay)
+      ! update node numbers and layer
       particle%idomain(2) = ic
       particle%icu = icu
       particle%ilay = ilay

src/Solution/ParticleTracker/MethodDisv.f90

@@ -155,12 +155,15 @@ subroutine load_particle(this, cell, particle)
       inbr = cell%defn%facenbr(inface)
       ipos = idiag + inbr
       ic = dis%con%ja(ipos)
+      icu = dis%get_nodeuser(ic)
+      call get_jk(icu, dis%ncpl, dis%nlay, icpl, ilay)
 
-      ! if returning to immediately previous cell
-      ! through its bottom, we've entered a cycle
-      ! as can occur e.g. in the bottom of wells.
-      ! terminate in the previous cell.
-      if (ic == particle%icp .and. inface == 7) then
+      ! if returning to a cell through the bottom
+      ! face after previously leaving it through  
+      ! that same face, we've entered a cycle
+      ! as can occur e.g. in wells. terminate
+      ! in the previous cell.
+      if (ic == particle%icp .and. inface == 7 .and. ilay < particle%ilay) then
         particle%advancing = .false.
         particle%idomain(2) = particle%icp
         particle%istatus = 2
@@ -172,10 +175,6 @@ subroutine load_particle(this, cell, particle)
         particle%izp = particle%izone
       end if
 
-      icu = dis%get_nodeuser(ic)
-
-      call get_jk(icu, dis%ncpl, dis%nlay, icpl, ilay)
-
       particle%idomain(2) = ic
       particle%icu = icu
       particle%ilay = ilay

src/Solution/ParticleTracker/vertical.md

@@ -130,4 +130,4 @@ flowchart LR
 
 In MF6.5, behavior was as described by `DROP`, with one major exception: lack of an exit face (i.e. any face with outgoing flow) took precedence over cell saturation; a particle finding itself in a dry cell with no outgoing flow would previously terminate, where if `DROP` is selected (or a dry tracking method unspecified) the pass-to-bottom method will now be applied instead.
 
-With this change, it also becomes necessary to prohibit particle backtracking (i.e. re-entering the previous cell) within the same time step, in order to avoid the possibility of infinite loops. For instance, a particle might otherwise be passed endlessly between e.g. the bottom face of a cell containing a pumping well and the top face of the cell below. 
+With this change, it also becomes necessary to prohibit backtracking between vertically adjacent pairs of cells within the same time step, in order to avoid the possibility of infinite loops — a particle might otherwise be passed endlessly between e.g. the bottom face of a cell containing a pumping well and the top face of the cell below. Note that this limitation applies only to vertically adjacent cells, and only to the immediately previous cell — a particle may re-enter a cell after entering a third cell.