phasicFlow/src/PostprocessData/operation/PostprocessOperation/PostprocessOperationSum.hpp

/*------------------------------- phasicFlow ---------------------------------
      O        C enter of
     O O       E ngineering and
    O   O      M ultiscale modeling of
   OOOOOOO     F luid flow
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#ifndef __PostprocessOperationSum_hpp__
#define __PostprocessOperationSum_hpp__

/*!
 * @class PostprocessOperationSum
 * @brief A class for summing field values within specified regions during post-processing.
 * 
 * @details
 * The PostprocessOperationSum class is a specialized post-processing operation that 
 * calculates the sum of field values within specified regions. It inherits from the 
 * postprocessOperation base class and implements a weighted summation operation that 
 * can be applied to scalar (real), vector (realx3), and tensor (realx4) fields.
 * 
 * The sum operation follows the mathematical formula:
 * \f[
 *    \text{result} = \sum_{i \in \text{processRegion}} w_i \cdot \phi_i \cdot \text{field}_i
 * \f]
 * 
 * Where:
 * - \f$ i \f$ represents particles within the specified processing region
 * - \f$ w_i \f$ is the weight factor for particle \f$ i \f$
 * - \f$ \phi_i \f$ is the value from the phi field for particle \f$ i \f$
 * - \f$ \text{field}_i \f$ is the value from the      target field for particle \f$ i \f$
 * 
 * The calculation can optionally be divided by the region volume (when divideByVolume is set to yes),
 * which allows calculating density-like quantities:
 * \f[
 *    \text{result} = \frac{1}{V_{\text{region}}} \sum_{i \in \text{processRegion}} w_i \cdot \phi_i \cdot \text{field}_i
 * \f]
 * 
 * The summation can be further filtered using an includeMask to selectively include only
 * specific particles that satisfy certain criteria.
 * 
 * This class supports the following field types:
 * - real (scalar values)
 * - realx3 (vector values)
 * - realx4 (tensor values)
 * 
 * @section usage Usage
 * 
 * To use the PostprocessOperationSum class in a postprocessDataDict file, the following
 * parameters can be specified:
 * 
 * - function: Must be set to "sum" to use this operation
 * - field: The name of the field to process (e.g., "velocity", "diameter", "one")
 *   - Special fields like "one" (constant value 1) are also supported
 *   - Expressions like "cube(diameter)" can be used for mathematical operations
 * - dividedByVolume: Whether to divide the sum by the region volume (yes/no, default: no)
 * - includeMask: Optional mask to filter which particles to include in the calculation
 * 
 * @section example Example Configuration
 * 
 * Here is an example configuration in the postprocessDataDict file:
 * 
 * @code
 * {
 *     processMethod    arithmetic; 
 *     processRegion    line;
 *     
 *     // the time interval for executing the post-processing 
 *     // other options: timeStep, default, and settings
 *     timeControl simulationTime; 
 *     startTime   1.0;
 *     endTime     3.0;
 *     executionInterval 0.1;
 *      
 *     // 10 spheres with radius 0.01 along the straight line defined by p1 and p2 
 *     lineInfo
 *     {
 *         p1 (0 0 0);
 *         p2 (0 0.15 0.15);
 *         numPoints 10;
 *         radius    0.01;
 *     }
 *     
 *     operations
 *     (
 *         // computes the number density (particles per unit volume)
 *         numberDensity
 *         {
 *             function       sum;
 *             field          one;        // constant field with value 1.0
 *             dividedByVolume yes;       // divide by region volume
 *         }
 *         
 *         // computes an approximation of volume fraction
 *         volumeDensity
 *         {
 *             function        sum;
 *             field           cube(diameter); // d^3, although it differs by pi/6
 *             dividedByVolume yes;
 *         }
 *     );
 * }
 * @endcode
 * 
 * In this example:
 * - numberDensity: Calculates the number of particles per unit volume
 * - volumeDensity: Calculates an approximation of the volume fraction using d³
 * 
 * @see postprocessOperation
 * @see executeSumOperation
 */

#include <variant>
#include <vector>

#include "postprocessOperation.hpp"
#include "regionField.hpp"
#include "includeMask.hpp"

namespace pFlow::postprocessData
{


class PostprocessOperationSum
:
    public postprocessOperation
{
private:
    /// Result field containing sums for each region (real, realx3, or realx4)
    uniquePtr<processedRegFieldType>  processedRegField_ = nullptr;

public:

    TypeInfo("PostprocessOperation<sum>");

    /// @brief Constructs sum operation processor
    /// @param opDict Operation parameters dictionary
    /// @param regPoints Region points data
    /// @param fieldsDB Fields database
    PostprocessOperationSum(
        const dictionary& opDict,
        const regionPoints& regPoints,
        fieldsDataBase& fieldsDB);
    
    PostprocessOperationSum(
        const dictionary& opDict,
        const word& fieldName,
        const word& phiName,
        const word& includeName,
        const regionPoints& regPoints,
        fieldsDataBase& fieldsDB);

    /// destructor 
    ~PostprocessOperationSum() override = default;

    /// add this virtual constructor to the base class
    add_vCtor
    (
        postprocessOperation,
        PostprocessOperationSum,
        dictionary
    );

    /// @brief Get the processed field containing regional sums
    /// @return Const reference to sum results
    const processedRegFieldType& processedField()const override
    {
        return processedRegField_();
    }

    /// @brief Execute sum operation on field values
    /// @param weights Weight factors for particles
    /// @return True if successful
    bool execute(
        const std::vector<span<real>>& weights,
        const regionField<real>& volFactor) override;

}; 


} // namespace pFlow::postprocessData

#endif //__PostprocessOperationSum_hpp__