 <OpenGeoSysProject>

   <mesh>elder.vtu</mesh>

   <geometry>elder-python.gml</geometry>

   <python_script>elder-python-bcs.py</python_script>

   <processes>

     <process>

       <name>HC</name>

       <type>ComponentTransport</type>

       <integration_order>2</integration_order>

       <process_variables>

         <concentration>Si</concentration>

         <pressure>pressure</pressure>

       </process_variables>

       <specific_body_force>0 0 -9.81</specific_body_force>

       <secondary_variables>

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

       </secondary_variables>

     </process>

   </processes>

   <media>

     <medium id="0">

       <phases>

         <phase>

           <type>AqueousLiquid</type>

           <components>

             <component>

               <name>Si</name>

               <properties>

                 <property>

                   <name>pore_diffusion</name>

                   <type>Constant</type>

                   <value>3.57e-6</value>

                 </property>

                 <property>

                   <name>retardation_factor</name>

                   <type>Constant</type>

                   <value>1</value>

                 </property>

                 <property>

                   <name>decay_rate</name>

                   <type>Parameter</type>

                   <parameter_name>decay_rate</parameter_name>

                 </property>

               </properties>

             </component>

           </components>

           <properties>

             <property>

               <name>density</name>

               <type>Linear</type>

               <reference_value>1000</reference_value>

               <independent_variable>

                 <variable_name>concentration</variable_name>

                 <reference_condition>0</reference_condition>

                 <slope>0.2</slope>

               </independent_variable>

             </property>

             <property>

               <name>viscosity</name>

               <type>Constant</type>

               <value>1e-3</value>

             </property>

           </properties>

         </phase>

       </phases>

       <properties>

         <property>

           <name>permeability</name>

           <type>Parameter</type>

           <parameter_name>kappa1</parameter_name>

         </property>

         <property>

           <name>porosity</name>

           <type>Parameter</type>

           <parameter_name>constant_porosity_parameter</parameter_name>

         </property>

         <property>

           <name>longitudinal_dispersivity</name>

           <type>Constant</type>

           <value>0</value>

         </property>

         <property>

           <name>transversal_dispersivity</name>

           <type>Constant</type>

           <value>0</value>

         </property>

       </properties>

     </medium>

   </media>

   <time_loop>

     <processes>

       <process ref="HC">

         <nonlinear_solver>basic_picard</nonlinear_solver>

         <convergence_criterion>

           <type>PerComponentDeltaX</type>

           <norm_type>NORM2</norm_type>

           <reltols>1e-3 1e-3</reltols>

         </convergence_criterion>

         <time_discretization>

           <type>BackwardEuler</type>

         </time_discretization>

         <time_stepping>

           <type>FixedTimeStepping</type>

           <t_initial>0.0</t_initial>

           <t_end>1.3149e8</t_end>

           <timesteps>

             <pair>

               <repeat>10</repeat>

               <delta_t>262980</delta_t>

             </pair>

           </timesteps>

         </time_stepping>

       </process>

     </processes>

     <output>

       <type>VTK</type>

       <prefix>elder_python</prefix>

       <timesteps>

         <pair>

           <repeat>1</repeat>

           <each_steps>20</each_steps>

         </pair>

       </timesteps>

       <variables>

         <variable>Si</variable>

         <variable>pressure</variable>

         <variable>darcy_velocity</variable>

       </variables>

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

     </output>

   </time_loop>

   <parameters>

     <parameter>

       <name>decay_rate</name>

       <type>Constant</type>

       <value>0.0</value>

     </parameter>

     <parameter>

       <name>p_ini</name>

       <type>MeshNode</type>

       <field_name>p_ini</field_name>

     </parameter>

     <parameter>

       <name>c_ini</name>

       <type>MeshNode</type>

       <field_name>c_ini</field_name>

     </parameter>

     <parameter>

       <name>constant_porosity_parameter</name>

       <type>Constant</type>

       <value>0.1</value>

     </parameter>

     <parameter>

       <name>kappa1</name>

       <type>Constant</type>

       <values>4.84404e-13 0 0 0 4.84404e-13 0 0 0 4.84404e-13</values>

     </parameter>

   </parameters>

   <process_variables>

     <process_variable>

       <name>Si</name>

       <components>1</components>

       <order>1</order>

       <initial_condition>c_ini</initial_condition>

       <boundary_conditions>

         <boundary_condition>

           <geometrical_set>elder</geometrical_set>

           <geometry>whole_domain_boundary</geometry>

           <type>Python</type>

           <bc_object>bc_c</bc_object>

         </boundary_condition>

       </boundary_conditions>

     </process_variable>

     <process_variable>

       <name>pressure</name>

       <components>1</components>

       <order>1</order>

       <initial_condition>p_ini</initial_condition>

       <boundary_conditions>

         <boundary_condition>

           <geometrical_set>elder</geometrical_set>

           <geometry>whole_domain_boundary</geometry>

           <type>Python</type>

           <bc_object>bc_p</bc_object>

         </boundary_condition>

       </boundary_conditions>

     </process_variable>

   </process_variables>

   <nonlinear_solvers>

     <nonlinear_solver>

       <name>basic_picard</name>

       <type>Picard</type>

       <max_iter>300</max_iter>

       <linear_solver>general_linear_solver</linear_solver>

     </nonlinear_solver>

   </nonlinear_solvers>

   <linear_solvers>

     <linear_solver>

       <name>general_linear_solver</name>

       <eigen>

         <precon_type>ILUT</precon_type>

         <solver_type>BiCGSTAB</solver_type>

         <max_iteration_step>5000</max_iteration_step>

         <error_tolerance>1e-12</error_tolerance>

       </eigen>

     </linear_solver>

   </linear_solvers>

 </OpenGeoSysProject>