diff --git a/source/simulator/solver/stokes_matrix_free_global_coarsening.cc b/source/simulator/solver/stokes_matrix_free_global_coarsening.cc
index dd30d459d4a..b398ebe3482 100644
--- a/source/simulator/solver/stokes_matrix_free_global_coarsening.cc
+++ b/source/simulator/solver/stokes_matrix_free_global_coarsening.cc
@@ -1574,7 +1574,7 @@ namespace aspect
 
             if (this->get_boundary_velocity_manager().get_tangential_boundary_velocity_indicators().size() > 0)
               {
-                Assert(false, dealii::StandardExceptions::ExcNotImplemented("This is not tested."));
+                // Assert(false, dealii::StandardExceptions::ExcNotImplemented("This is not tested."));
                 VectorTools::compute_no_normal_flux_constraints (dof_handler,
                                                                  0 /* first_vector_component */,
                                                                  this->get_boundary_velocity_manager().get_tangential_boundary_velocity_indicators(),
diff --git a/tests/shell_2d_gmg_gc.prm b/tests/shell_2d_gmg_gc.prm
new file mode 100644
index 00000000000..ae191942662
--- /dev/null
+++ b/tests/shell_2d_gmg_gc.prm
@@ -0,0 +1,82 @@
+# 2d shell with no flux top boundary to test GMG
+
+
+set Dimension                              = 2
+set Use years instead of seconds           = true
+set End time                               = 1.0e5
+set Output directory                       = output-shell_2d_gmg
+
+subsection Material model
+  set Model name = simple
+  set Material averaging = harmonic average only viscosity
+
+  subsection Simple model
+    set Thermal expansion coefficient = 4e-5
+    set Viscosity                     = 1e22
+  end
+end
+
+subsection Geometry model
+  set Model name = spherical shell
+
+  subsection Spherical shell
+    set Inner radius  = 3481000
+    set Outer radius  = 6336000
+    set Opening angle = 360
+  end
+end
+
+subsection Boundary velocity model
+  set Zero velocity boundary indicators       = inner
+  set Tangential velocity boundary indicators = top
+end
+
+subsection Heating model
+  set List of model names =  shear heating
+end
+
+subsection Boundary temperature model
+  set Fixed temperature boundary indicators = top, bottom
+  set List of model names = spherical constant
+
+  subsection Spherical constant
+    set Inner temperature = 4273
+    set Outer temperature = 973
+  end
+end
+
+subsection Initial temperature model
+  set Model name = spherical hexagonal perturbation
+end
+
+subsection Gravity model
+  set Model name = ascii data
+end
+
+subsection Mesh refinement
+  set Initial global refinement          = 2
+  set Initial adaptive refinement        = 2
+  set Strategy                           = temperature
+  set Time steps between mesh refinement = 15
+end
+
+subsection Postprocess
+  set List of postprocessors = visualization, velocity statistics, temperature statistics, heat flux statistics, depth average
+
+  subsection Visualization
+    set Output format                 = vtu
+    set Time between graphical output = 1e6
+    set Number of grouped files       = 0
+  end
+
+  subsection Depth average
+    set Time between graphical output = 1e5
+  end
+end
+
+subsection Solver parameters
+  subsection Stokes solver parameters
+    set Stokes solver type = block GMG
+    set Stokes GMG type = global coarsening
+  end
+end
diff --git a/tests/shell_2d_gmg_gc/screen-output b/tests/shell_2d_gmg_gc/screen-output
new file mode 100644
index 00000000000..09c6c729008
--- /dev/null
+++ b/tests/shell_2d_gmg_gc/screen-output
@@ -0,0 +1,43 @@
+
+Number of active cells: 192 (on 3 levels)
+Number of degrees of freedom: 2,832 (1,728+240+864)
+
+*** Timestep 0:  t=0 years, dt=0 years
+   Solving temperature system... 0 iterations.
+   Solving Stokes system (GMG-GC)... 15+0 iterations.
+
+Number of active cells: 300 (on 4 levels)
+Number of degrees of freedom: 4,782 (2,928+390+1,464)
+
+*** Timestep 0:  t=0 years, dt=0 years
+   Solving temperature system... 0 iterations.
+   Solving Stokes system (GMG-GC)... 33+0 iterations.
+
+Number of active cells: 444 (on 4 levels)
+Number of degrees of freedom: 6,888 (4,224+552+2,112)
+
+*** Timestep 0:  t=0 years, dt=0 years
+   Solving temperature system... 0 iterations.
+   Solving Stokes system (GMG-GC)... 15+0 iterations.
+
+   Postprocessing:
+     Writing graphical output:           output-shell_2d_gmg_gc/solution/solution-00000
+     RMS, max velocity:                  0.0795 m/year, 0.129 m/year
+     Temperature min/avg/max:            973 K, 2463 K, 4273 K
+     Heat fluxes through boundary parts: 1.127e+06 W, 2.941e+06 W
+     Writing depth average:              output-shell_2d_gmg_gc/depth_average
+
+*** Timestep 1:  t=100000 years, dt=100000 years
+   Solving temperature system... 8 iterations.
+   Solving Stokes system (GMG-GC)... 11+0 iterations.
+
+   Postprocessing:
+     RMS, max velocity:                  0.0856 m/year, 0.138 m/year
+     Temperature min/avg/max:            973 K, 2463 K, 4273 K
+     Heat fluxes through boundary parts: -3.351e+05 W, 4.462e+06 W
+     Writing depth average:              output-shell_2d_gmg_gc/depth_average
+
+Termination requested by criterion: end time
+
+
+