Merge pull request #6220 from jdannberg/particle_initialization

re-generate particles in initial adaptive refinement

doc/modules/changes/20250129_jdannberg

@@ -0,0 +1,7 @@
+Changed: ASPECT now re-generates particles in each initial
+adaptive refinement cycle instead of only once after global
+refinement. This means that particle locations during initial
+adaptive refinement are chosen according to the generator
+instead of randomly.
+<br>
+(Juliane Dannberg, 2025/01/29)

source/particle/manager.cc

@@ -574,9 +574,14 @@ namespace aspect
     void
     Manager<dim>::setup_initial_state ()
     {
-      // If we are in the first adaptive refinement cycle generate particles
-      if (this->get_pre_refinement_step() == 0)
-        generate_particles();
+      // We want to generate a new set of particles in each adaptive refinement
+      // cycle to get the right number of particles per cell and to accurately
+      // initialize their properties. Delete existing particles beforehand.
+      if (this->get_pre_refinement_step() > 0)
+        particle_handler->clear();
+
+      // Generate particles in each adaptive refinement cycle
+      generate_particles();
 
       // And initialize the particle properties according to the initial
       // conditions on the current mesh

tests/grain_size_crossed_transition/screen-output

@@ -29,40 +29,40 @@ Number of degrees of freedom: 5,285 (2,482+321+1,241+1,241)
 
    Postprocessing:
      Writing graphical output:  output-grain_size_crossed_transition/solution/solution-00001
-     Compositions min/max/mass: 0.001313/0.002/5.938e+07
+     Compositions min/max/mass: 0.00135/0.002/5.942e+07
      Writing particle output:   output-grain_size_crossed_transition/particles/particles-00001
 
-*** Timestep 2:  t=6442.31 years, dt=3220.42 years
+*** Timestep 2:  t=6439.33 years, dt=3217.44 years
    Solving temperature system... 0 iterations.
    Advecting particles...  done.
    Rebuilding Stokes preconditioner...
    Solving Stokes system (AMG)... 29+0 iterations.
 
    Postprocessing:
      Writing graphical output:  output-grain_size_crossed_transition/solution/solution-00002
-     Compositions min/max/mass: 0.001/0.002/5.876e+07
+     Compositions min/max/mass: 0.001/0.002/5.879e+07
      Writing particle output:   output-grain_size_crossed_transition/particles/particles-00002
 
-*** Timestep 3:  t=9648.75 years, dt=3206.45 years
+*** Timestep 3:  t=9649.24 years, dt=3209.91 years
    Solving temperature system... 0 iterations.
    Advecting particles...  done.
    Rebuilding Stokes preconditioner...
-   Solving Stokes system (AMG)... 30+0 iterations.
+   Solving Stokes system (AMG)... 29+0 iterations.
 
    Postprocessing:
      Writing graphical output:  output-grain_size_crossed_transition/solution/solution-00003
-     Compositions min/max/mass: 0.001/0.002/5.816e+07
+     Compositions min/max/mass: 0.001/0.002/5.822e+07
      Writing particle output:   output-grain_size_crossed_transition/particles/particles-00003
 
-*** Timestep 4:  t=10000 years, dt=351.245 years
+*** Timestep 4:  t=10000 years, dt=350.761 years
    Solving temperature system... 0 iterations.
    Advecting particles...  done.
    Rebuilding Stokes preconditioner...
-   Solving Stokes system (AMG)... 25+0 iterations.
+   Solving Stokes system (AMG)... 24+0 iterations.
 
    Postprocessing:
      Writing graphical output:  output-grain_size_crossed_transition/solution/solution-00004
-     Compositions min/max/mass: 0.001/0.002/5.81e+07
+     Compositions min/max/mass: 0.001/0.002/5.815e+07
      Writing particle output:   output-grain_size_crossed_transition/particles/particles-00004
 
 Termination requested by criterion: end time

tests/grain_size_crossed_transition/statistics

@@ -16,7 +16,7 @@
 # 16: Number of advected particles
 # 17: Particle file name
 0 0.000000000000e+00 0.000000000000e+00 264 2803 1241 1241 0 30 32 160 output-grain_size_crossed_transition/solution/solution-00000 2.00000000e-03 2.00000000e-03 6.00000000e+07 10000 output-grain_size_crossed_transition/particles/particles-00000 
-1 3.221888105682e+03 3.221888105682e+03 264 2803 1241 1241 0 24 26 130 output-grain_size_crossed_transition/solution/solution-00001 1.31250000e-03 2.00000000e-03 5.93820271e+07  9956 output-grain_size_crossed_transition/particles/particles-00001 
-2 6.442308952690e+03 3.220420847008e+03 264 2803 1241 1241 0 28 30 150 output-grain_size_crossed_transition/solution/solution-00002 1.00000000e-03 2.00000000e-03 5.87617466e+07  9890 output-grain_size_crossed_transition/particles/particles-00002 
-3 9.648754753904e+03 3.206445801214e+03 264 2803 1241 1241 0 29 31 155 output-grain_size_crossed_transition/solution/solution-00003 1.00000000e-03 2.00000000e-03 5.81631659e+07  9815 output-grain_size_crossed_transition/particles/particles-00003 
-4 1.000000000000e+04 3.512452460959e+02 264 2803 1241 1241 0 24 26 130 output-grain_size_crossed_transition/solution/solution-00004 1.00000000e-03 2.00000000e-03 5.81049139e+07  9811 output-grain_size_crossed_transition/particles/particles-00004 
+1 3.221888105682e+03 3.221888105682e+03 264 2803 1241 1241 0 24 26 130 output-grain_size_crossed_transition/solution/solution-00001 1.35000000e-03 2.00000000e-03 5.94221251e+07  9877 output-grain_size_crossed_transition/particles/particles-00001 
+2 6.439327373120e+03 3.217439267438e+03 264 2803 1241 1241 0 28 30 150 output-grain_size_crossed_transition/solution/solution-00002 1.00000000e-03 2.00000000e-03 5.87878710e+07  9750 output-grain_size_crossed_transition/particles/particles-00002 
+3 9.649238592234e+03 3.209911219114e+03 264 2803 1241 1241 0 28 30 150 output-grain_size_crossed_transition/solution/solution-00003 1.00000000e-03 2.00000000e-03 5.82190312e+07  9604 output-grain_size_crossed_transition/particles/particles-00003 
+4 1.000000000000e+04 3.507614077663e+02 264 2803 1241 1241 0 23 25 125 output-grain_size_crossed_transition/solution/solution-00004 1.00000000e-03 2.00000000e-03 5.81477550e+07  9593 output-grain_size_crossed_transition/particles/particles-00004 

tests/particle_generator_reference_cell_adaptive.prm

@@ -0,0 +1,21 @@
+# Like particle_generator_reference_cell.prm but with initial adaptive
+# refinement to test correct particle initialization.
+# There should be 4 particles per direction within each cell.
+
+set Dimension = 2
+
+include $ASPECT_SOURCE_DIR/tests/particle_generator_reference_cell.prm
+
+subsection Mesh refinement
+  set Initial adaptive refinement        = 1
+  set Strategy                           = composition gradient
+  set Initial global refinement          = 3
+  set Coarsening fraction                = 0.6
+  set Refinement fraction                = 0.15
+  set Adapt by fraction of cells         = true
+end
+
+subsection Particles
+  set Load balancing strategy = remove and add particles
+  set Minimum particles per cell = 16
+end