use BiCGStab-ILU0 as the linear solver for the lens problem

... and use the parallel AMG solver for the CO2 injection problem.

this makes performance comparisions with Dumux much easier as the
solver performance should be more similar.

examples/problems/co2injectionproblem.hh

@@ -25,6 +25,7 @@
 #define EWOMS_CO2_INJECTION_PROBLEM_HH
 
 #include <ewoms/models/immiscible/immisciblemodel.hh>
+#include <ewoms/linear/parallelamgbackend.hh>
 
 #include <opm/material/fluidsystems/H2ON2FluidSystem.hpp>
 #include <opm/material/fluidsystems/BrineCO2FluidSystem.hpp>
@@ -131,6 +132,9 @@ public:
     typedef Opm::Somerton<FluidSystem, Scalar> type;
 };
 
+// Use the algebraic multi-grid linear solver for this problem
+SET_TAG_PROP(Co2InjectionBaseProblem, LinearSolverSplice, ParallelAmgLinearSolver);
+
 // Write the Newton convergence behavior to disk?
 SET_BOOL_PROP(Co2InjectionBaseProblem, NewtonWriteConvergence, false);