Start with a coarser grid

src/one-body-sample.cc

@@ -199,7 +199,7 @@ int main(int argc, char *argv[]) {
         1); // nth dimension (zero-indexed) goes from 0 to end_points[n]
     GridType grid(
         end_points,
-        Dune::FieldVector<int, dim>(2), // number of elements in each direction
+        Dune::FieldVector<int, dim>(1), // number of elements in each direction
         Dune::FieldVector<bool, dim>(false), // non-periodic in each direction
         0);                                  // zero overlap (whatever that is)
     grid.globalRefine(refinements);