diff --git a/ProcessLib/LiquidFlow/Tests.cmake b/ProcessLib/LiquidFlow/Tests.cmake
index 05ae2845bfb51cef49aaee980f2e733d80186266..c878614c294e9e71b385818f35a851af6257b243 100644
--- a/ProcessLib/LiquidFlow/Tests.cmake
+++ b/ProcessLib/LiquidFlow/Tests.cmake
@@ -381,7 +381,7 @@ AddTest(
)
AddTest(
- NAME LiquidFlow_Flux_2D
+ NAME LiquidFlow_Flux_2D_Quads
PATH Parabolic/LiquidFlow/Flux/2D
EXECUTABLE ogs
EXECUTABLE_ARGS square_1e1_calculatesurfaceflux.prj
@@ -395,6 +395,21 @@ AddTest(
LF_square_1e1_surfaceflux_pcs_0_ts_2_t_0.864000_expected.vtu LF_square_1e1_surfaceflux_pcs_0_ts_2_t_0.864000.vtu pressure pressure 1e-7 1e-13
)
+AddTest(
+ NAME LiquidFlow_Flux_2D_Tris
+ PATH Parabolic/LiquidFlow/Flux/2D
+ EXECUTABLE ogs
+ EXECUTABLE_ARGS square_1.8e1_calculatesurfaceflux.prj
+ WRAPPER time
+ TESTER vtkdiff
+ REQUIREMENTS NOT OGS_USE_MPI
+ DIFF_DATA
+ square_1x1_tri_1.8e1_complete_boundary_left_right_dirichlet_specific_flux_t_0.432000_expected.vtu square_1x1_tri_1.8e1_complete_boundary_left_right_dirichlet_specific_flux_t_0.432000.vtu specific_flux specific_flux 1e-7 1e-13
+ square_1x1_tri_1.8e1_complete_boundary_left_right_dirichlet_specific_flux_t_0.864000_expected.vtu square_1x1_tri_1.8e1_complete_boundary_left_right_dirichlet_specific_flux_t_0.864000.vtu specific_flux specific_flux 1e-7 1e-13
+ LF_square_1x1_tri_1.8e1_surfaceflux_pcs_0_ts_1_t_0.432000_expected.vtu LF_square_1x1_tri_1.8e1_surfaceflux_pcs_0_ts_1_t_0.432000.vtu pressure pressure 1e-7 1e-13
+ LF_square_1x1_tri_1.8e1_surfaceflux_pcs_0_ts_2_t_0.864000_expected.vtu LF_square_1x1_tri_1.8e1_surfaceflux_pcs_0_ts_2_t_0.864000.vtu pressure pressure 1e-7 1e-13
+)
+
#AddTest(
# NAME LiquidFlow_SimpleSynthetics_constraint_dirichlet_bc
# PATH Parabolic/LiquidFlow/SimpleSynthetics
diff --git a/Tests/Data/Parabolic/LiquidFlow/Flux/2D/LF_square_1x1_tri_1.8e1_surfaceflux_pcs_0_ts_1_t_0.432000_expected.vtu b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/LF_square_1x1_tri_1.8e1_surfaceflux_pcs_0_ts_1_t_0.432000_expected.vtu
new file mode 100644
index 0000000000000000000000000000000000000000..d8084ca93e7b43ca1ffdad7025b6fce6162ebd60
--- /dev/null
+++ b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/LF_square_1x1_tri_1.8e1_surfaceflux_pcs_0_ts_1_t_0.432000_expected.vtu
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:aa13e751c56fb0bf8f2334c5206d1c5fc4bc4e0355dee25ddeec679c0db7a692
+size 2702
diff --git a/Tests/Data/Parabolic/LiquidFlow/Flux/2D/LF_square_1x1_tri_1.8e1_surfaceflux_pcs_0_ts_2_t_0.864000_expected.vtu b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/LF_square_1x1_tri_1.8e1_surfaceflux_pcs_0_ts_2_t_0.864000_expected.vtu
new file mode 100644
index 0000000000000000000000000000000000000000..f24e8c9177e1f8061bd1de133d9f4fedf9666590
--- /dev/null
+++ b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/LF_square_1x1_tri_1.8e1_surfaceflux_pcs_0_ts_2_t_0.864000_expected.vtu
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
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+size 2666
diff --git a/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1.8e1_calculatesurfaceflux.prj b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1.8e1_calculatesurfaceflux.prj
new file mode 100644
index 0000000000000000000000000000000000000000..f6f2780035c8c99c6a5e337e3c57bb4017a30043
--- /dev/null
+++ b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1.8e1_calculatesurfaceflux.prj
@@ -0,0 +1,192 @@
+<?xml version="1.0" encoding="ISO-8859-1"?>
+<OpenGeoSysProject>
+ <meshes>
+ <mesh>square_1x1_tri_1.8e1.vtu</mesh>
+ <mesh>square_1x1_tri_1.8e1_complete_boundary.vtu</mesh>
+ <mesh>square_1x1_tri_1.8e1_left.vtu</mesh>
+ <mesh>square_1x1_tri_1.8e1_right.vtu</mesh>
+ </meshes>
+ <processes>
+ <process>
+ <name>LiquidFlow</name>
+ <type>LIQUID_FLOW</type>
+ <integration_order>2</integration_order>
+ <darcy_gravity>
+ <!-- axis_id: 0, 1, or the dimension of space minus one -->
+ <axis_id>0</axis_id>
+ <!-- g>=0. g=0: non gravity term -->
+ <g>0.</g>
+ </darcy_gravity>
+ <process_variables>
+ <process_variable>pressure</process_variable>
+ </process_variables>
+ <secondary_variables>
+ <secondary_variable internal_name="darcy_velocity" output_name="v"/>
+ </secondary_variables>
+ <calculatesurfaceflux>
+ <mesh>square_1x1_tri_1.8e1_complete_boundary</mesh>
+ <property_name>specific_flux</property_name>
+ <output_mesh>square_1x1_tri_1.8e1_complete_boundary_left_right_dirichlet_specific_flux.vtu</output_mesh>
+ </calculatesurfaceflux>
+ </process>
+ </processes>
+ <time_loop>
+ <processes>
+ <process ref="LiquidFlow">
+ <nonlinear_solver>basic_picard</nonlinear_solver>
+ <convergence_criterion>
+ <type>DeltaX</type>
+ <norm_type>NORM2</norm_type>
+ <abstol>1.e-10</abstol>
+ </convergence_criterion>
+ <time_discretization>
+ <type>BackwardEuler</type>
+ </time_discretization>
+ <time_stepping>
+ <type>FixedTimeStepping</type>
+ <t_initial> 0.0 </t_initial>
+ <t_end> 0.864 </t_end>
+ <timesteps>
+ <pair>
+ <repeat>2</repeat>
+ <delta_t>0.432</delta_t>
+ </pair>
+ </timesteps>
+ </time_stepping>
+ </process>
+ </processes>
+ <output>
+ <type>VTK</type>
+ <prefix>LF_square_1x1_tri_1.8e1_surfaceflux</prefix>
+ <timesteps>
+ <pair>
+ <repeat> 1 </repeat>
+ <each_steps> 1 </each_steps>
+ </pair>
+ </timesteps>
+ <variables>
+ <variable> pressure </variable>
+ <variable> v </variable>
+ </variables>
+ </output>
+ </time_loop>
+ <media>
+ <medium id="0">
+ <phases>
+ <phase>
+ <type>AqueousLiquid</type>
+ <properties>
+ <property>
+ <name>viscosity</name>
+ <type>Constant</type>
+ <value> 1.295e-4 </value>
+ </property>
+ <property>
+ <name>density</name>
+ <type>Constant</type>
+ <value> 78.68 </value>
+ </property>
+ </properties>
+ </phase>
+ </phases>
+ <properties>
+ <property>
+ <name>permeability</name>
+ <type>Constant</type>
+ <value>9.2e-12 0 0 9.2e-12</value>
+ </property>
+ <property>
+ <name>reference_temperature</name>
+ <type>Constant</type>
+ <value>293.15</value>
+ </property>
+ <property>
+ <name>porosity</name>
+ <type>Constant</type>
+ <value>1</value>
+ </property>
+ <property>
+ <name>storage</name>
+ <type>Constant</type>
+ <value> 8.05e-10 </value>
+ </property>
+ </properties>
+ </medium>
+ </media>
+ <parameters>
+ <parameter>
+ <name>p0</name>
+ <type>Constant</type>
+ <value>5e6</value>
+ </parameter>
+ <parameter>
+ <name>p_Dirichlet_left</name>
+ <type>Constant</type>
+ <value>1e7</value>
+ </parameter>
+ <parameter>
+ <name>p_Dirichlet_right</name>
+ <type>Constant</type>
+ <value>1e6</value>
+ </parameter>
+ <parameter>
+ <name>constant_porosity_parameter</name>
+ <type>Constant</type>
+ <value>1</value>
+ </parameter>
+ <parameter>
+ <name>kappa1</name>
+ <type>Constant</type>
+ <values>9.2e-12 0 0 9.2e-12</values>
+ </parameter>
+ <parameter>
+ <name>p_spatial</name>
+ <type>Constant</type>
+ <value>1</value>
+ </parameter>
+ </parameters>
+ <process_variables>
+ <process_variable>
+ <name>pressure</name>
+ <components>1</components>
+ <order>1</order>
+ <initial_condition>p0</initial_condition>
+ <boundary_conditions>
+ <boundary_condition>
+ <mesh>square_1x1_tri_1.8e1_left</mesh>
+ <type>Dirichlet</type>
+ <parameter>p_Dirichlet_left</parameter>
+ </boundary_condition>
+ <boundary_condition>
+ <mesh>square_1x1_tri_1.8e1_right</mesh>
+ <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>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>lf</prefix>
+ <parameters>-lf_ksp_type cg -lf_pc_type bjacobi -lf_ksp_rtol 1e-16 -lf_ksp_max_it 10000</parameters>
+ </petsc>
+ </linear_solver>
+ </linear_solvers>
+</OpenGeoSysProject>
diff --git a/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1.vtu b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1.vtu
new file mode 100644
index 0000000000000000000000000000000000000000..f3efd25363bfe3a3a25e6d8a85fc838d21966553
--- /dev/null
+++ b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1.vtu
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
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+size 2468
diff --git a/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_complete_boundary.vtu b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_complete_boundary.vtu
new file mode 100644
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+++ b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_complete_boundary.vtu
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diff --git a/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_complete_boundary_left_right_dirichlet_specific_flux_t_0.432000_expected.vtu b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_complete_boundary_left_right_dirichlet_specific_flux_t_0.432000_expected.vtu
new file mode 100644
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diff --git a/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_complete_boundary_left_right_dirichlet_specific_flux_t_0.864000_expected.vtu b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_complete_boundary_left_right_dirichlet_specific_flux_t_0.864000_expected.vtu
new file mode 100644
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diff --git a/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_left.vtu b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_left.vtu
new file mode 100644
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+++ b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_left.vtu
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diff --git a/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_right.vtu b/Tests/Data/Parabolic/LiquidFlow/Flux/2D/square_1x1_tri_1.8e1_right.vtu
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