Adding InterpolatedFluidProperties

Fluid properties can be given as a grid of values. Then, bicubic interpolation
is created from those values and used for evaluation.

CMakeLists.txt

@@ -20,6 +20,7 @@ option(FPROPS_WITH_PYTHON "Build python wrapper" YES)
 option(FPROPS_BUILD_TESTS "Build tests" NO)
 
 find_package(HDF5 1.8 COMPONENTS C HL REQUIRED)
+find_package(Eigen3 3.3.4 REQUIRED)
 find_package(fmt 8.0 REQUIRED)
 if (FPROPS_WITH_PYTHON)
     add_subdirectory(python)

cmake/CodeCoverage.cmake

@@ -25,6 +25,9 @@ if(FPROPS_CODE_COVERAGE)
         set_property(DIRECTORY APPEND PROPERTY ADDITIONAL_CLEAN_FILES "${CODE_COVERAGE_PROFRAWS}")
 
         set(EXCLUDE_REGEX
+                --ignore-filename-regex=/contrib/
+                --ignore-filename-regex=/include/eigen3/
+                --ignore-filename-regex=/include/fmt/
         )
 
         set(CODE_COVERAGE_BINS
@@ -111,8 +114,10 @@ if(FPROPS_CODE_COVERAGE)
         )
 
         set(EXCLUDE_REGEX
+            --exclude=*/contrib/*
             --exclude=/usr/include/*
             --exclude=*/include/fmt/*
+            --exclude=*/include/eigen3/*
         )
 
         add_custom_target(coverage DEPENDS ${COVERAGE_INFO})

include/InterpolatedFluidProperties.h

@@ -0,0 +1,167 @@
+#pragma once
+
+#include "SinglePhaseFluidProperties.h"
+#include <Eigen/Dense>
+#include <vector>
+#include <array>
+#include <string>
+
+namespace h5pp {
+class File;
+}
+
+namespace fprops {
+
+typedef Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor> DynDenseMatrix;
+typedef Eigen::Matrix<Eigen::Matrix4d, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor>
+    CoefficientMatrix;
+
+class InterpolatedFluidProperties : public SinglePhaseFluidProperties {
+public:
+    InterpolatedFluidProperties();
+    virtual ~InterpolatedFluidProperties() = default;
+
+    /// Load data set from an HDF5 file
+    ///
+    /// @param file_name HDF5 file name
+    virtual void load(const std::string & file_name);
+
+    State p_T(double p, double T) const override;
+    State rho_T(double rho, double T) const override;
+    State rho_p(double rho, double p) const override;
+    State v_u(double v, double u) const override;
+    State h_s(double h, double s) const override;
+
+protected:
+    /// Fluid property data set
+    ///
+    /// Data set consists of 2 independent variables and a set of dependent values.
+    /// Independent variables are given as an 1D array of values in ascending order.
+    /// Dependent variables are given as a 2D array of values with dimension (size of 1st indep.
+    /// variable, size od 2nd indep. variable).
+    class FPDataSet {
+        /// Number of dependent values
+        static constexpr std::size_t N = 12;
+
+    public:
+        /// Check if the data exists
+        ///
+        /// @return `true` if this is a valid data set, `false` is this is an empty data set
+        bool empty() const;
+
+        /// Evaluate variables at location (x1, x2)
+        ///
+        /// @param x1 Value of 1st independent variable
+        /// @param x2 Value of 2nd independent variable
+        /// @param val_idx Indices of dependent variables to compute
+        /// @return Values of computed variables
+        std::array<double, N>
+        eval(double x1, double x2, const std::vector<std::size_t> & val_idx) const;
+
+        /// Set range for 1st independent variable
+        ///
+        /// @param values Values of 1st independent variable
+        void set_range_1(const Eigen::VectorXd & values);
+
+        /// Set range for 2nd independent variable
+        ///
+        /// @param values Values of 2nd independent variable
+        void set_range_2(const Eigen::VectorXd & values);
+
+        /// Compute coefficient matrix for a dependent variable
+        ///
+        /// @param idx Index of the dependent variable
+        /// @param y Data grid with dependent variable values
+        void set_values(std::size_t idx, const DynDenseMatrix & y);
+
+    protected:
+        /// List of the first independent variable
+        Eigen::VectorXd x1;
+        /// List of the second independent variable
+        Eigen::VectorXd x2;
+        /// Coefficient matrices for dependent variables
+        std::array<CoefficientMatrix, N> values;
+
+        /// Calculate derivatives of a 2D array with variable values
+        ///
+        /// @param y Variable values
+        /// @param dydx1 Computed 1st derivative wrt 1st independent variable
+        /// @param dydx2 Computed 1st derivative wrt 2st independent variable
+        /// @param dydx1x2 Computed mixed derivative wrt 1st and 2nd independent variable
+        void calc_derivatives(const DynDenseMatrix & y,
+                              DynDenseMatrix & dydx1,
+                              DynDenseMatrix & dydx2,
+                              DynDenseMatrix & dydx1x2);
+    };
+
+    /// Check units listed on the dataset
+    ///
+    /// If expected unit is not found and exception is thrown
+    ///
+    /// @param file HDF5 file
+    /// @param dataset_name Dataset name
+    /// @param unit Expected unit
+    void
+    check_unit(const h5pp::File & file, const std::string & dataset_name, const std::string & unit);
+
+    /// Read fluid property values from a group
+    ///
+    /// @param file HDF5 file
+    /// @param group_name Group name to read from
+    /// @param vars Independent variables
+    /// @param idxs Indices of dependent variables
+    /// @return Fluid property data set to evaluate as a list of variable indices
+    FPDataSet read_data(const h5pp::File & file,
+                        const std::string & group_name,
+                        const std::pair<std::size_t, std::size_t> & vars,
+                        const std::vector<std::size_t> & idxs);
+
+    /// Read independent variable values
+    ///
+    /// @param file HDF5 file
+    /// @param group_name Group name
+    /// @param var_idx Index of an independent variable
+    /// @return Vector of independent variable values
+    Eigen::VectorXd
+    read_var_range(const h5pp::File & file, const std::string & group_name, std::size_t var_idx);
+
+    /// Read dependent variable values
+    ///
+    /// @param file HDF5 file
+    /// @param group_name Group name
+    /// @param var_idx Index of an dependent variable
+    /// @return Grid values as a 2D array (represented as a matrix)
+    DynDenseMatrix
+    read_grid(const h5pp::File & file, const std::string & group_name, std::size_t var_idx);
+
+    /// Indices for computed quantities and indexing into var_names, var_units, etc.
+    static const std::size_t U;
+    static const std::size_t V;
+    static const std::size_t RHO;
+    static const std::size_t P;
+    static const std::size_t T;
+    static const std::size_t MU;
+    static const std::size_t CP;
+    static const std::size_t CV;
+    static const std::size_t S;
+    static const std::size_t K;
+    static const std::size_t H;
+    static const std::size_t W;
+
+    /// Fluid properties depending on pressure and temperature
+    FPDataSet pT_data;
+    /// Fluid properties depending on density and temperature
+    FPDataSet rhoT_data;
+    /// Fluid properties depending on density and pressure
+    FPDataSet rhop_data;
+    /// Fluid properties depending on specific volume and internal energy
+    FPDataSet vu_data;
+    /// Fluid properties depending on enthalpy and entropy
+    FPDataSet hs_data;
+    /// Variable names
+    std::vector<std::string> var_names;
+    /// Variable units
+    std::vector<std::string> var_units;
+};
+
+} // namespace fprops

python/src/CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.4...3.18)
-project(pyfprops LANGUAGES CXX)
+project(pyfprops LANGUAGES C CXX)
 
 find_package(pybind11 2.9 REQUIRED)
 
@@ -10,6 +10,7 @@ target_include_directories(
     PRIVATE
         ${CMAKE_BINARY_DIR}
         ${CMAKE_SOURCE_DIR}/include
+        ${EIGEN3_INCLUDE_DIR}
 )
 
 target_link_libraries(

src/CMakeLists.txt

@@ -6,6 +6,7 @@ add_library(
         Helium.cpp
         Helmholtz.cpp
         IdealGas.cpp
+        InterpolatedFluidProperties.cpp
         Nitrogen.cpp
         Numerics.cpp
         Props.cpp
@@ -33,6 +34,7 @@ target_include_directories(
         ${CMAKE_BINARY_DIR}
         ${CMAKE_SOURCE_DIR}/contrib
         ${HDF5_INCLUDE_DIR}
+        ${EIGEN3_INCLUDE_DIR}
 )
 
 target_link_libraries(