Added test for spherical constant boundary composition with a sphere

tests/boundary_composition_spherical_constant_3D_sphere.prm

@@ -0,0 +1,72 @@
+# This test ensures that the spherical constant
+# boundary composition sets the composition
+# at the surface of a sphere
+
+set Dimension                              = 2
+set End time                               = 0
+
+subsection Boundary temperature model
+  set Model name = initial temperature 
+end
+
+subsection Compositional fields
+  set Number of fields          = 1 
+end
+
+subsection Initial composition model
+  set List of model names = function
+  subsection Function
+    set Function expression = 1
+  end
+end
+
+subsection Boundary composition model
+  set Model name = spherical constant
+  subsection Spherical constant
+    set Surface composition = 0
+  end
+end
+
+subsection Geometry model
+  set Model name = sphere
+end
+
+subsection Gravity model
+  set Model name = vertical 
+  subsection Vertical
+    set Magnitude = 9.81 
+  end
+end
+
+subsection Initial temperature model
+  set Model name = function 
+  subsection Function
+    set Function expression = 500
+  end
+end
+
+subsection Material model
+  set Model name         = simpler
+  subsection Simpler model
+  set Viscosity = 1e21
+  end
+end
+
+subsection Mesh refinement
+  set Initial adaptive refinement              = 0         
+  set Initial global refinement                = 2           
+end
+
+subsection Model settings
+  set Fixed composition boundary indicators   = 0	
+  set Tangential velocity boundary indicators = 0
+end
+
+subsection Postprocess
+  set List of postprocessors = visualization
+  subsection Visualization
+    set List of output variables = depth
+    set Output format = gnuplot
+  end
+end
+