 <OpenGeoSysProject>

   <mesh>square_1x1_quad_1e3.vtu</mesh>

   <geometry>square_1x1.gml</geometry>

   <processes>

     <process>

       <name>IsothermalFluidFlow</name>

       <type>HT</type>

       <integration_order>2</integration_order>

       <process_variables>

         <temperature>T</temperature>

         <pressure>p</pressure>

       </process_variables>

       <specific_body_force>0 0</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>

           <properties>

             <property>

               <name>specific_heat_capacity</name>

               <type>Constant</type>

               <value>0</value>

             </property>

             <property>

               <name>thermal_conductivity</name>

               <type>Constant</type>

               <value>0.65</value>

             </property>

             <property>

               <name>density</name>

               <type>Constant</type>

               <value>1.0e-3</value>

             </property>

             <property>

               <name>viscosity</name>

               <type>Constant</type>

               <value>1.0e-3</value>

             </property>

           </properties>

         </phase>

         <phase>

           <type>Solid</type>

           <properties>

             <property>

               <name>storage</name>

               <type>Constant</type>

               <value>0.0</value>

             </property>

             <property>

               <name>density</name>

               <type>Constant</type>

               <value>0.0</value>

             </property>

             <property>

               <name>specific_heat_capacity</name>

               <type>Constant</type>

               <value>0</value>

             </property>

             <property>

               <name>thermal_conductivity</name>

               <type>Constant</type>

               <value>3.0</value>

             </property>

           </properties>

         </phase>

       </phases>

       <properties>

         <property>

           <name>thermal_longitudinal_dispersivity</name>

           <type>Constant</type>

           <value>0</value>

         </property>

         <property>

           <name>thermal_transversal_dispersivity</name>

           <type>Constant</type>

           <value>0</value>

         </property>

         <property>

           <name>permeability</name>

           <type>Constant</type>

           <value>1.e-14 0 0 1.e-14</value>

         </property>

         <property>

           <name>porosity</name>

           <type>Constant</type>

           <value>0.001</value>

         </property>

         <property>

           <name>thermal_conductivity</name>

           <type>EffectiveThermalConductivityPorosityMixing</type>

         </property>

       </properties>

     </medium>

   </media>

   <time_loop>

     <processes>

       <process ref="IsothermalFluidFlow">

         <nonlinear_solver>basic_picard</nonlinear_solver>

         <convergence_criterion>

           <type>DeltaX</type>

           <norm_type>NORM2</norm_type>

           <abstol>1.e-3</abstol>

         </convergence_criterion>

         <time_discretization>

           <type>BackwardEuler</type>

         </time_discretization>

         <time_stepping>

           <type>FixedTimeStepping</type>

           <t_initial>0.0</t_initial>

           <t_end>1</t_end>

           <timesteps>

             <pair>

               <repeat>1</repeat>

               <delta_t>1</delta_t>

             </pair>

           </timesteps>

         </time_stepping>

       </process>

     </processes>

     <outputs>

       <output>

         <type>VTK</type>

         <prefix>IsothermalFluidFlow</prefix>

         <timesteps>

           <pair>

             <repeat>1</repeat>

             <each_steps>1</each_steps>

           </pair>

         </timesteps>

         <variables />

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

       </output>

       <output>

         <type>XDMF</type>

         <prefix>empty_variables_IsothermalFluidFlow</prefix>

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

         <timesteps>

           <pair>

             <repeat>1</repeat>

             <each_steps>1</each_steps>

           </pair>

         </timesteps>

         <variables />

       </output>

       <output>

         <type>XDMF</type>

         <prefix>full_variables_IsothermalFluidFlow</prefix>

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

         <timesteps>

           <pair>

             <repeat>1</repeat>

             <each_steps>1</each_steps>

           </pair>

         </timesteps>

         <variables>

           <variable>T</variable>

           <variable>darcy_velocity</variable>

           <variable>p</variable>

         </variables>

       </output>

     </outputs>

   </time_loop>

   <parameters>

     <parameter>

       <name>T0</name>

       <type>Constant</type>

       <value>0</value>

     </parameter>

     <parameter>

       <name>P0</name>

       <type>Constant</type>

       <value>0</value>

     </parameter>

     <parameter>

       <name>p_Dirichlet_left</name>

       <type>Constant</type>

       <value>1</value>

     </parameter>

     <parameter>

       <name>p_Dirichlet_right</name>

       <type>Constant</type>

       <value>-1</value>

     </parameter>

     <parameter>

       <name>t_Dirichlet_bottom</name>

       <type>Constant</type>

       <value>0</value>

     </parameter>

     <parameter>

       <name>t_Dirichlet_top</name>

       <type>Constant</type>

       <value>0</value>

     </parameter>

   </parameters>

   <process_variables>

     <process_variable>

       <name>T</name>

       <components>1</components>

       <order>1</order>

       <initial_condition>T0</initial_condition>

       <boundary_conditions>

         <boundary_condition>

           <geometrical_set>geometry</geometrical_set>

           <geometry>bottom</geometry>

           <type>Dirichlet</type>

           <parameter>t_Dirichlet_bottom</parameter>

         </boundary_condition>

         <boundary_condition>

           <geometrical_set>geometry</geometrical_set>

           <geometry>top</geometry>

           <type>Dirichlet</type>

           <parameter>t_Dirichlet_top</parameter>

         </boundary_condition>

       </boundary_conditions>

     </process_variable>

     <process_variable>

       <name>p</name>

       <components>1</components>

       <order>1</order>

       <initial_condition>P0</initial_condition>

       <boundary_conditions>

         <boundary_condition>

           <geometrical_set>geometry</geometrical_set>

           <geometry>left</geometry>

           <type>Dirichlet</type>

           <parameter>p_Dirichlet_left</parameter>

         </boundary_condition>

         <boundary_condition>

           <geometrical_set>geometry</geometrical_set>

           <geometry>right</geometry>

           <type>Dirichlet</type>

           <parameter>p_Dirichlet_right</parameter>

         </boundary_condition>

       </boundary_conditions>

     </process_variable>

   </process_variables>

   <nonlinear_solvers>

     <nonlinear_solver>

       <name>basic_picard</name>

       <type>Picard</type>

       <max_iter>1000</max_iter>

       <linear_solver>general_linear_solver</linear_solver>

     </nonlinear_solver>

   </nonlinear_solvers>

   <linear_solvers>

     <linear_solver>

       <name>general_linear_solver</name>

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

       <petsc>

         <prefix>HT</prefix>

         <parameters>-HT_ksp_type bcgs -HT_pc_type bjacobi -HT_ksp_rtol 1e-16 -HT_ksp_max_it 4000</parameters>

       </petsc>

       <eigen>

         <solver_type>BiCGSTAB</solver_type>

         <precon_type>ILUT</precon_type>

         <max_iteration_step>10000</max_iteration_step>

         <error_tolerance>1e-16</error_tolerance>

       </eigen>

     </linear_solver>

   </linear_solvers>

 </OpenGeoSysProject>