OpenFOAM中的Chemistry类

化学反应相关的类，以热学相关的类为基础，它位于路径src/chemistryModel/。它的类间关系如下：

接下来我们逐个介绍这些类的内容

basicChemistryModel

最基础的类，头文件内容如下：

class basicChemistryModel
:
    public IOdictionary
{
protected:
        //- Reference to the mesh database
        const fvMesh& mesh_;
        //- Chemistry activation switch
        Switch chemistry_;
        //- Initial chemical time step
        const scalar deltaTChemIni_;
        //- Maximum chemical time step
        const scalar deltaTChemMax_;
        //- Latest estimation of integration step
        volScalarField::Internal deltaTChem_;

        构造函数和析构函数
        返回类中的成员变量

        //- Return const access to chemical source terms
        virtual const volScalarField::Internal& R(const label i)=0
        //- Return reaction rate of the speciei in reactioni
        virtual tmp<volScalarField::Internal> calculateRR(const label reactioni,const label speciei)=0
        //Solve the reaction system for the given time step
        virtual scalar solve(const scalar deltaT) = 0;
        //- Return the heat release rate [kg/m/s^3]
        virtual tmp<volScalarField> Qdot() const = 0；
}；

最重要的功能是最后几个函数，可以计算化学源项，以及反映速率。还有chemFoam中使用的solve函数，以及放热速率。不过这里的几个函数均为纯虚函数，需要后面给出具体的实现

BasicChemistryModel

其头文件内容如下：

template<class ReactionThermo>
class BasicChemistryModel
:
    public basicChemistryModel
{
protected:
        //- Thermo
        ReactionThermo& thermo_;

        构造函数和析构函数
        返回成员变量thermo_
 };

相当于在基础类basicChemistryModel的基础上，添加了热学相关的类。但是并没有给出前面的纯虚函数的具体定义。

StandardChemistryModel

类的描述如下：

Description
    Extends base chemistry model by adding a thermo package, and ODE functions.
    Introduces chemistry equation system and evaluation of chemical source
    terms.
    在基础类上添加热学包，和ode函数。引入化学方程和化学源项的实现

头文件内容如下：

template<class ReactionThermo, class ThermoType>
class StandardChemistryModel
:
    public BasicChemistryModel<ReactionThermo>,
    public ODESystem
{    成员变量，含有各种组分的信息，以及反应速率
     //- Reference to the field of specie mass fractions
     PtrList<volScalarField>& Y_;
     //- Reactions
     const PtrList<Reaction<ThermoType>>& reactions_;
     //- Thermodynamic data of the species
     const PtrList<ThermoType>& specieThermo_;
     //- Number of species
     label nSpecie_;
     //- Number of reactions
     label nReaction_;
     //- Temperature below which the reaction rates are assumed 0
     scalar Treact_;
     //- List of reaction rate per specie [kg/m^3/s]
     PtrList<volScalarField::Internal> RR_;
     //- Temporary concentration field
     mutable scalarField c_;
     //- Temporary rate-of-change of concentration field
     mutable scalarField dcdt_;

     构造函数和析构函数
     各类功能性的成员函数
};

这里我们比较关注的是solve函数具体实现，这里把它贴出来：

template<class ReactionThermo, class ThermoType>
template<class DeltaTType>
Foam::scalar Foam::StandardChemistryModel<ReactionThermo, ThermoType>::solve
(
    const DeltaTType& deltaT
)
{
    BasicChemistryModel<ReactionThermo>::correct();

    scalar deltaTMin = great;

    if (!this->chemistry_)
    {
        return deltaTMin;
    }

    tmp<volScalarField> trho(this->thermo().rho());
    const scalarField& rho = trho();   //得到密度域

    const scalarField& T = this->thermo().T(); //得到速度和压力域
    const scalarField& p = this->thermo().p();

    scalarField c0(nSpecie_); //得到各个组分的浓度

    forAll(rho, celli) //对每个单元遍历
    {
        scalar Ti = T[celli];

        if (Ti > Treact_) //超出燃点后才会发生反应
        {
            const scalar rhoi = rho[celli]; //取出域中的单个密度和压力
            scalar pi = p[celli];

            for (label i=0; i<nSpecie_; i++)  //对每个组分计算浓度
            {
                c_[i] = rhoi*Y_[i][celli]/specieThermo_[i].W();
                c0[i] = c_[i];
            }

            // Initialise time progress
            scalar timeLeft = deltaT[celli];

            // Calculate the chemical source terms 计算化学源项，调用另外一个solve
            while (timeLeft > small)
            {
                scalar dt = timeLeft;
                this->solve(c_, Ti, pi, dt, this->deltaTChem_[celli]);
                timeLeft -= dt;
            }

            deltaTMin = min(this->deltaTChem_[celli], deltaTMin);

            this->deltaTChem_[celli] =
                min(this->deltaTChem_[celli], this->deltaTChemMax_);

            for (label i=0; i<nSpecie_; i++)  //计算反应速率
            {
                RR_[i][celli] =
                    (c_[i] - c0[i])*specieThermo_[i].W()/deltaT[celli];
            }
        }
        else //如果温度未到，反应速率就为零
        {
            for (label i=0; i<nSpecie_; i++)
            {
                RR_[i][celli] = 0;
            }
        }
    }

    return deltaTMin;
}

TDACChemistryModel

首先看描述

Description
    Extends StandardChemistryModel by adding the TDAC method.

    References:
    \\verbatim
        Contino, F., Jeanmart, H., Lucchini, T., & D’Errico, G. (2011).
        Coupling of in situ adaptive tabulation and dynamic adaptive chemistry:
        An effective method for solving combustion in engine simulations.
        Proceedings of the Combustion Institute, 33(2), 3057-3064.

        Contino, F., Lucchini, T., D'Errico, G., Duynslaegher, C.,
        Dias, V., & Jeanmart, H. (2012).
        Simulations of advanced combustion modes using detailed chemistry
        combined with tabulation and mechanism reduction techniques.
        SAE International Journal of Engines,
        5(2012-01-0145), 185-196.

        Contino, F., Foucher, F., Dagaut, P., Lucchini, T., D’Errico, G., &
        Mounaïm-Rousselle, C. (2013).
        Experimental and numerical analysis of nitric oxide effect on the
        ignition of iso-octane in a single cylinder HCCI engine.
        Combustion and Flame, 160(8), 1476-1483.

        Contino, F., Masurier, J. B., Foucher, F., Lucchini, T., D’Errico, G., &
        Dagaut, P. (2014).
        CFD simulations using the TDAC method to model iso-octane combustion
        for a large range of ozone seeding and temperature conditions
        in a single cylinder HCCI engine.
        Fuel, 137, 179-184.
    \\endverbatim

类继承自StandardChemistryModel，这里使用了一个新的方法TDAC并给出了若干参考文献。这里也给出了solve一个实现，这里不再继续展开