 <OpenGeoSysProject>

   <meshes>

     <mesh>domain.vtu</mesh>

     <mesh>left.vtu</mesh>

     <mesh>right.vtu</mesh>

   </meshes>

   <processes>

     <process>

       <name>HeatConduction</name>

       <type>HEAT_CONDUCTION</type>

       <integration_order>2</integration_order>

       <process_variables>

         <process_variable>temperature</process_variable>

       </process_variables>

       <secondary_variables>

         <secondary_variable internal_name="heat_flux" output_name="heat_flux" />

       </secondary_variables>

     </process>

   </processes>

   <time_loop>

     <processes>

       <process ref="HeatConduction">

         <nonlinear_solver>basic_picard</nonlinear_solver>

         <convergence_criterion>

           <type>DeltaX</type>

           <norm_type>NORM2</norm_type>

           <abstol>1.e-6</abstol>

         </convergence_criterion>

         <time_discretization>

           <type>BackwardEuler</type>

         </time_discretization>

         <time_stepping>

           <type>FixedTimeStepping</type>

           <t_initial>0.0</t_initial>

           <t_end>8.6400e+4</t_end>

           <timesteps>

             <pair>

               <repeat>10</repeat>

               <delta_t>8.6400e+3</delta_t>

             </pair>

           </timesteps>

         </time_stepping>

       </process>

     </processes>

     <output>

       <type>VTK</type>

       <prefix>time_decay_bc</prefix>

       <timesteps>

         <pair>

           <repeat>10</repeat>

           <each_steps>1</each_steps>

         </pair>

       </timesteps>

       <variables>

         <variable>temperature</variable>

         <variable>heat_flux</variable>

       </variables>

       <suffix>ts{:timestep}_t_{:time}</suffix>

     </output>

   </time_loop>

   <media>

     <medium id="4">

       <phases />

       <properties>

         <property>

           <name>thermal_conductivity</name>

           <type>Constant</type>

           <value>5</value>

         </property>

         <property>

           <name>specific_heat_capacity</name>

           <type>Constant</type>

           <value>1000</value>

         </property>

         <property>

           <name>density</name>

           <type>Constant</type>

           <value>2500</value>

         </property>

       </properties>

     </medium>

   </media>

   <parameters>

     <parameter>

       <name>T0</name>

       <type>Function</type>

       <expression>320.0 + 30 * y;</expression>

     </parameter>

     <parameter>

       <name>decay_function</name>

       <type>Function</type>

       <expression>if (t>4.32e+4) 0.0; else 1 - t/ 4.32e+4;</expression>

     </parameter>

   </parameters>

   <process_variables>

     <process_variable>

       <name>temperature</name>

       <components>1</components>

       <order>1</order>

       <initial_condition>T0</initial_condition>

       <boundary_conditions>

         <boundary_condition>

           <mesh>right</mesh>

           <type>Dirichlet</type>

           <parameter>T0</parameter>

         </boundary_condition>

         <boundary_condition>

           <mesh>left</mesh>

           <type>TimeDecayDirichlet</type>

           <time_decay_parameter>decay_function</time_decay_parameter>

           <lower_limit>290</lower_limit>

         </boundary_condition>

       </boundary_conditions>

     </process_variable>

   </process_variables>

   <nonlinear_solvers>

     <nonlinear_solver>

       <name>basic_picard</name>

       <type>Picard</type>

       <max_iter>10</max_iter>

       <linear_solver>general_linear_solver</linear_solver>

     </nonlinear_solver>

   </nonlinear_solvers>

   <linear_solvers>

     <linear_solver>

       <name>general_linear_solver</name>

       <lis>-i cg -p jacobi -tol 1e-16 -maxiter 10000</lis>

       <eigen>

         <solver_type>CG</solver_type>

         <precon_type>DIAGONAL</precon_type>

         <max_iteration_step>10000</max_iteration_step>

         <error_tolerance>1e-16</error_tolerance>

       </eigen>

       <petsc>

         <prefix>gw</prefix>

         <parameters>-gw_ksp_type cg -gw_pc_type bjacobi -gw_ksp_rtol 1e-16 -gw_ksp_max_it 10000</parameters>

       </petsc>

     </linear_solver>

   </linear_solvers>

   <test_definition>

     <vtkdiff>

       <file>time_decay_bc_ts_5_t_43200.000000.vtu</file>

       <field>temperature</field>

       <absolute_tolerance>1e-8</absolute_tolerance>

       <relative_tolerance>0</relative_tolerance>

     </vtkdiff>

     <vtkdiff>

       <file>time_decay_bc_ts_10_t_86400.000000.vtu</file>

       <field>temperature</field>

       <absolute_tolerance>1e-8</absolute_tolerance>

       <relative_tolerance>0</relative_tolerance>

     </vtkdiff>

   </test_definition>

 </OpenGeoSysProject>