Merge pull request #5221 from jdannberg/merged_boxes_origin

correctly set up two merged boxes for nonzero Y origin

doc/modules/changes/20230708_dannberg

@@ -0,0 +1,5 @@
+Fixed: The computation of the upper box origin in the 'box
+with lithosphere boundary indicators' geometry model did not 
+take into account a nonzero origin. This is fixed now.
+<br>
+(Juliane Dannberg, 2023/07/08)

source/geometry_model/two_merged_boxes.cc

@@ -507,7 +507,7 @@ namespace aspect
             {
               lower_extents[1]     = extents[1] - thickness_lith;
               upper_extents[1]     = thickness_lith;
-              upper_box_origin[1]  = lower_extents[1];
+              upper_box_origin[1]  = lower_box_origin[1] + lower_extents[1];
               upper_repetitions[1] = prm.get_integer ("Y repetitions lithosphere");
             }
 
@@ -524,13 +524,13 @@ namespace aspect
               lower_extents[2]     = extents[2] - thickness_lith;
               upper_extents[2]     = thickness_lith;
               lower_box_origin[2]  = prm.get_double ("Box origin Z coordinate");
-              upper_box_origin[2]  = lower_extents[2];
+              upper_box_origin[2]  = lower_box_origin[2] + lower_extents[2];
               periodic[2]          = prm.get_bool ("Z periodic");
               lower_repetitions[2] = prm.get_integer ("Z repetitions");
               upper_repetitions[2] = prm.get_integer ("Z repetitions lithosphere");
             }
 
-          height_lith = extents[dim-1] - thickness_lith;
+          height_lith = upper_box_origin[dim-1];
           use_merged_grids = prm.get_bool ("Use merged grids");
         }
         prm.leave_subsection();

tests/lithosphere_boundary_indicator_origin.prm

@@ -0,0 +1,14 @@
+# With this geometry model we add 2 additional boundary
+# indicators to the lithospheric part of the left and right
+# boundary.
+# This test is for a nonzero box Y origin.
+
+include $ASPECT_SOURCE_DIR/tests/lithosphere_boundary_indicator.prm
+
+subsection Geometry model
+  set Model name = box with lithosphere boundary indicators
+
+  subsection Box with lithosphere boundary indicators
+    set Box origin Y coordinate = 300000
+  end
+end

tests/lithosphere_boundary_indicator_origin/screen-output

@@ -0,0 +1,28 @@
+-----------------------------------------------------------------------------
+-----------------------------------------------------------------------------
+
+-----------------------------------------------------------------------------
+-----------------------------------------------------------------------------
+Number of active cells: 2,048 (on 6 levels)
+Number of degrees of freedom: 35,685 (16,770+2,145+8,385+8,385)
+
+*** Timestep 0:  t=0 years, dt=0 years
+   Skipping temperature solve because RHS is zero.
+   Solving C_1 system ... 0 iterations.
+   Rebuilding Stokes preconditioner...
+   Solving Stokes system... 200+2 iterations.
+
+   Postprocessing:
+     RMS, max velocity:        0.00375 m/year, 0.01 m/year
+     Pressure min/avg/max:     -1.724e+06 Pa, 9.771e+09 Pa, 1.961e+10 Pa
+     Writing graphical output: output-lithosphere_boundary_indicator_origin/solution/solution-00000
+
+Termination requested by criterion: end time
+
+
++----------------------------------------------+------------+------------+
++----------------------------------+-----------+------------+------------+
++----------------------------------+-----------+------------+------------+
+
+-----------------------------------------------------------------------------
+-----------------------------------------------------------------------------