[cig-commits] commit 2004 by heister to /var/svn/dealii/aspect

[dealii.demon at gmail.com]

Revision 2004

add 'Nonlinear solver tolerance' and abort iteration if reached

U   trunk/aspect/doc/modules/changes.h
U   trunk/aspect/include/aspect/simulator.h
U   trunk/aspect/source/simulator/core.cc
U   trunk/aspect/source/simulator/parameters.cc


http://www.dealii.org/websvn/revision.php?repname=Aspect+Repository&path=%2F&rev=2004&peg=2004

Diff:
Modified: trunk/aspect/doc/modules/changes.h
===================================================================
--- trunk/aspect/doc/modules/changes.h	2013-11-02 23:20:52 UTC (rev 2003)
+++ trunk/aspect/doc/modules/changes.h	2013-11-02 23:22:19 UTC (rev 2004)
@@ -8,6 +8,11 @@
 </p>
 
 <ol>
+  <li>New: the "iterated Stokes" nonlinear solver will now stop iterating
+  if the residual is smaller than the new "Nonlinear solver tolerance".
+  <br>
+  (Timo Heister 2013/11/02)
+
   <li>New: add a visual postprocessor that outputs the artificial
   viscosity parameter for the temperature equation on each cell.
   <br>

Modified: trunk/aspect/include/aspect/simulator.h
===================================================================
--- trunk/aspect/include/aspect/simulator.h	2013-11-02 23:20:52 UTC (rev 2003)
+++ trunk/aspect/include/aspect/simulator.h	2013-11-02 23:22:19 UTC (rev 2004)
@@ -158,6 +158,7 @@
 
         NonlinearSolverKind            nonlinear_solver;
 
+        double                         nonlinear_tolerance;
         bool                           resume_computation;
         double                         start_time;
         double                         CFL_number;

Modified: trunk/aspect/source/simulator/core.cc
===================================================================
--- trunk/aspect/source/simulator/core.cc	2013-11-02 23:20:52 UTC (rev 2003)
+++ trunk/aspect/source/simulator/core.cc	2013-11-02 23:22:19 UTC (rev 2004)
@@ -1094,6 +1094,11 @@
                 = solution.block(introspection.block_indices.compositional_fields[c]);
             }
 
+
+          // residual vector (only for the velocity)
+          LinearAlgebra::Vector residual (introspection.index_sets.system_partitioning[0], mpi_communicator);
+          LinearAlgebra::Vector tmp (introspection.index_sets.system_partitioning[0], mpi_communicator);
+
           // ...and then iterate the solution
           // of the Stokes system
           for (unsigned int i=0; i< parameters.max_nonlinear_iterations; ++i)
@@ -1106,11 +1111,21 @@
               assemble_stokes_system();
               build_stokes_preconditioner();
               solve_stokes();
+
+              // check for convergence:
+              residual = solution.block(introspection.block_indices.velocities);
+              tmp = current_linearization_point.block(introspection.block_indices.velocities);
+              residual -= tmp; // TODO: why can I not use a ghosted vector to read from?!
+              pcout << "	residual: " << residual.l2_norm() << std::endl;
+              if (residual.l2_norm() < parameters.nonlinear_tolerance)
+                break;
+
               current_linearization_point.block(introspection.block_indices.velocities)
                 = solution.block(introspection.block_indices.velocities);
               current_linearization_point.block(introspection.block_indices.pressure)
                 = solution.block(introspection.block_indices.pressure);
 
+
               pcout << std::endl;
             }
 

Modified: trunk/aspect/source/simulator/parameters.cc
===================================================================
--- trunk/aspect/source/simulator/parameters.cc	2013-11-02 23:20:52 UTC (rev 2003)
+++ trunk/aspect/source/simulator/parameters.cc	2013-11-02 23:22:19 UTC (rev 2004)
@@ -135,6 +135,12 @@
                        "temperature equation (careful, the material model must not depend on "
                        "the temperature; mostly useful for Stokes benchmarks).");
 
+    prm.declare_entry ("Nonlinear solver tolerance", "1e-9",
+                       Patterns::Double(0,1),
+                       "A relative tolerance up to which the nonlinear solver "
+                       "will iterate. This parameter is only relevant if "
+                       "Nonlinear solver scheme is set to 'iterated Stokes'.");
+
     prm.declare_entry ("Pressure normalization", "surface",
                        Patterns::Selection ("surface|volume|no"),
                        "If and how to normalize the pressure after the solution step. "
@@ -503,6 +509,8 @@
     else
       AssertThrow (false, ExcNotImplemented());
 
+    nonlinear_tolerance = prm.get_double("Nonlinear solver tolerance");
+
     max_nonlinear_iterations = prm.get_integer ("Max nonlinear iterations");
     start_time              = prm.get_double ("Start time");
     if (convert_to_years == true)