added Test for Brooks&Corey saturation property

Tests/MaterialLib/TestMPLSaturationBrooksCorey.cpp

+/**
+ * \file
+ *
+ * \copyright
+ * Copyright (c) 2012-2019, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/project/license
+ *
+ */
+#include <gtest/gtest.h>
+#include <sstream>
+
+#include "TestMPL.h"
+#include "Tests/TestTools.h"
+
+#include "MaterialLib/MPL/Medium.h"
+#include "MaterialLib/MPL/Properties/SaturationBrooksCorey.h"
+
+TEST(MaterialPropertyLib, SaturationBrooksCorey)
+{
+    const double ref_lambda = 2.5;
+    const double ref_residual_liquid_saturation = 0.12;
+    const double ref_residual_gas_saturation = 0.06;
+    const double ref_entry_pressure = 5678.54;
+
+    const double max_saturation = 1. - ref_residual_gas_saturation;
+
+    std::stringstream m;
+    m << "<medium>\n";
+    m << "<phases></phases>\n";
+    m << "<properties>\n";
+    m << "  <property>\n";
+    m << "    <name>saturation</name>\n";
+    m << "    <type>SaturationBrooksCorey</type>\n";
+    m << "    <residual_liquid_saturation>" << ref_residual_liquid_saturation
+      << "</residual_liquid_saturation>\n";
+    m << "    <residual_gas_saturation>" << ref_residual_gas_saturation
+      << "</residual_gas_saturation>\n";
+    m << "    <lambda>" << ref_lambda << "</lambda>\n";
+    m << "    <entry_pressure>" << ref_entry_pressure << "</entry_pressure>\n";
+    m << "  </property> \n";
+    m << "</properties>\n";
+    m << "</medium>\n";
+
+    auto const& medium = createTestMaterial(m.str());
+
+    MaterialPropertyLib::VariableArray variable_array;
+    ParameterLib::SpatialPosition const pos;
+    double const time = std::numeric_limits<double>::quiet_NaN();
+
+    variable_array[static_cast<int>(
+        MaterialPropertyLib::Variable::capillary_pressure)] = 0.0;
+
+    auto s_L = medium->property(MaterialPropertyLib::PropertyType::saturation)
+                   .template value<double>(variable_array, pos, time);
+    auto ds_L_dp_cap =
+        medium->property(MaterialPropertyLib::PropertyType::saturation)
+            .template dValue<double>(
+                variable_array,
+                MaterialPropertyLib::Variable::capillary_pressure,
+                pos,
+                time);
+
+    ASSERT_EQ(s_L, max_saturation);
+    ASSERT_EQ(ds_L_dp_cap, 0.);
+
+    for (double p_cap = 1.0; p_cap < 1.0e10; p_cap *= 1.5)
+    {
+        variable_array[static_cast<int>(
+            MaterialPropertyLib::Variable::capillary_pressure)] = p_cap;
+
+        s_L = medium->property(MaterialPropertyLib::PropertyType::saturation)
+                  .template value<double>(variable_array, pos, time);
+        ds_L_dp_cap =
+            medium->property(MaterialPropertyLib::PropertyType::saturation)
+                .template dValue<double>(
+                    variable_array,
+                    MaterialPropertyLib::Variable::capillary_pressure,
+                    pos,
+                    time);
+
+        const double s_eff =
+            std::pow(ref_entry_pressure / std::max(p_cap, ref_entry_pressure),
+                     ref_lambda);
+        const double s_ref =
+            s_eff * (max_saturation - ref_residual_liquid_saturation) +
+            ref_residual_liquid_saturation;
+        const double ds_dpc =
+            (p_cap <= ref_entry_pressure) ? 0. : -ref_lambda / p_cap * s_ref;
+
+        ASSERT_NEAR(s_L, s_ref, 1.e-10);
+        ASSERT_NEAR(ds_L_dp_cap, ds_dpc, 1.e-10);
+    }
+}
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