请教在OF8中用multiphaseEulerFoam求解器时，依时边界条件为什么会报错？

[durm17]

本算例采用的是气液两相流，想要给空气相加一个速度边界条件，而水相不加这个边界条件，下面给出的这个边界条件是空气相的，是依时的边界条件，按照网站上相似的做法编了以下，但是始终出现如下错误。请各位老师同学有时间帮忙解答一下，非常感谢！
下面是边界条件：

    afInlet
    {
        type               codedFixedValue;
        value	  	    $internalField;
        redirectType	    ramp;
        name		    sinewave;
        code
        #{
        	#include <math.h>
        	scalar t = this->db().time().value();
        	fvPatchField<vector> u
        	(

        		
        		patch().lookupPatchField<volVectorField,vector>("U.air")
      
        	);
        	u[t] = vector(0,0,2*3.1416*10/1000/0.77*1*sin(2*3.1416*1*t));
        	(*this) == u;
   
        #};

下面是报错的内容：

--> FOAM FATAL ERROR: 

    request for volVectorField U from objectRegistry region0 failed
    available objects of type volVectorField are

8
(
HbyA.air
U.air
U.water
U.air_0
KdUByA.air
U.water_0
KdUByA.water
HbyA.water
)


    From function const Type& Foam::objectRegistry::lookupObject(const Foam::word&) const [with Type = Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>]
    in file /home/dyfluid/OpenFOAM/OpenFOAM-8/src/OpenFOAM/lnInclude/objectRegistryTemplates.C at line 211.

FOAM aborting

#0  Foam::error::printStack(Foam::Ostream&) at ??:?
#1  Foam::error::abort() at ??:?
#2  Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> const& Foam::objectRegistry::lookupObject<Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> >(Foam::word const&) const in "/home/dyfluid/OpenFOAM/OpenFOAM-8/platforms/linux64GccDPInt32Opt/bin/multiphaseEulerFoam"
#3  Foam::totalPressureFvPatchScalarField::updateCoeffs() at ??:?
#4  Foam::fvMatrix<double>::fvMatrix(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::dimensionSet const&) in "/home/dyfluid/OpenFOAM/OpenFOAM-8/platforms/linux64GccDPInt32Opt/bin/multiphaseEulerFoam"
#5  ? in "/home/dyfluid/OpenFOAM/OpenFOAM-8/platforms/linux64GccDPInt32Opt/bin/multiphaseEulerFoam"
#6  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#7  ? in "/home/dyfluid/OpenFOAM/OpenFOAM-8/platforms/linux64GccDPInt32Opt/bin/multiphaseEulerFoam"
Aborted (core dumped)