foundObject，返回是否找到该对象的 Bool 值
lookupObject，返回对象，只能使用const成员函数，
lookupObjectRef，返回的对象可以使用非const成员函数

最简单的场量：

this->mesh().objectRegistry::lookupObject<volScalarField>("rho")
this->mesh().objectRegistry::lookupObject<volVectorField>("U")
this->mesh().objectRegistry::lookupObject<PtrList<scalarField>>("this->thermo().composition().Y()")

模型

湍流模型

const compressible::turbulenceModel& turbModel =
    this->db().objectRegistry::lookupObject<compressible::turbulenceModel>
    ("turbulence");

const compressible::turbulenceModel& turbModel =
	lookupObject<compressible::turbulenceModel>
	(
	    turbulenceModel::propertiesName
	);

const compressible::turbulenceModel& turbModel =
	this->db().lookupObject<compressible::turbulenceModel>
	(
	    turbulenceModel::propertiesName
	);

const compressible::turbulenceModel& turbModel =
	db().lookupObject<compressible::turbulenceModel>
	(
	    IOobject::groupName
	    (
	        compressible::turbulenceModel::propertiesName,
	        internalField().group()
	    )
	);
    
const compressible::LESModel& lesModel =
	YO2.db().lookupObject<compressible::LESModel>
	(
	    turbulenceModel::propertiesName
	);    

喷雾模型

if (this->mesh().objectRegistry::foundObject<sprayCloud>(Foam::sprayCloud::typeName))
const basicSprayCloud& spray_ = dynamic_cast<const basicSprayCloud&>(this->mesh().objectRegistry::lookupObject<sprayCloud>(Foam::sprayCloud::typeName));
basicSprayCloud& spray_ = dynamic_cast<basicSprayCloud&>(this->mesh().objectRegistry::lookupObjectRef<sprayCloud>(Foam::sprayCloud::typeName));

探索

输出所有注册在网格上的量：

wordList allFields = this->mesh().sortedNames();
Info<<"allFields ="<<allFields<<endl;

输出的量都是可以通过找对象的方式获取的，但是类型要靠我们自己得到。