message: Valgrind error.
diff: @@ -84,6 +84,7 @@ void AdvectorCG::ComputeAtNewPosition(const Vector &new_nodes,
  if (v_max == 0.0)
  {
  // No mesh motion --> no need to change the field.
  + delete oper;
  return;
  }
  v_max = std::sqrt(v_max);
  