Diffusion Class Reference

Collaboration diagram for Diffusion:

Public Member Functions
	Diffusion (int argc, char *argv[])
	~Diffusion ()
void	TimeIntegrate ()
void	DoImplicitSolve (const Array< OneD, const Array< OneD, NekDouble > > &inarray, Array< OneD, Array< OneD, NekDouble > > &outarray, const NekDouble time, const NekDouble lambda)

Private Member Functions
void	WriteSolution ()
void	ExactSolution ()

Private Attributes
LibUtilities::SessionReaderSharedPtr	session
LibUtilities::FieldIOSharedPtr	fld
string	sessionName
SpatialDomains::MeshGraphSharedPtr	graph
MultiRegions::ContField2DSharedPtr	field
LibUtilities::TimeIntegrationWrapperSharedPtr	IntScheme
LibUtilities::TimeIntegrationSolutionSharedPtr	u
LibUtilities::TimeIntegrationSchemeOperators	ode
Array< OneD, Array< OneD, NekDouble > >	fields
string	scheme
unsigned int	nSteps
NekDouble	delta_t
NekDouble	epsilon
NekDouble	lambda

Detailed Description

Definition at line 46 of file DiffusionSolverTimeInt.cpp.

Constructor & Destructor Documentation

Diffusion::Diffusion	(	int	argc,
		char *	argv[]
	)

Definition at line 83 of file DiffusionSolverTimeInt.cpp.

References Nektar::MemoryManager< DataType >::AllocateSharedPtr(), Nektar::LibUtilities::SessionReader::CreateInstance(), and Nektar::SpatialDomains::MeshGraph::Read().

{
    // Create session reader.
    session     = LibUtilities::SessionReader::CreateInstance(argc, argv);

    // Create Field I/O object.
    fld         = MemoryManager<LibUtilities::FieldIO>::
                    AllocateSharedPtr(session->GetComm());

    // Get some information from the session
    sessionName = session->GetSessionName();
    scheme      = session->GetSolverInfo("TimeIntegrationMethod");
    nSteps      = session->GetParameter("NumSteps");
    delta_t     = session->GetParameter("TimeStep");
    epsilon     = session->GetParameter("epsilon");
    lambda      = 1.0/delta_t/epsilon;

    // Read the geometry and the expansion information
    graph       = SpatialDomains::MeshGraph::Read(session);

    // Set up the field
    field       = MemoryManager<MultiRegions::ContField2D>::
                    AllocateSharedPtr(session, graph, session->GetVariable(0));

    fields      = Array<OneD, Array<OneD, NekDouble> >(1);
    fields[0]   = field->UpdatePhys();

    // Get coordinates of physical points
    unsigned int nq = field->GetNpoints();
    Array<OneD,NekDouble> x0(nq), x1(nq), x2(nq);
    field->GetCoords(x0,x1,x2);

    // Evaluate initial condition
    LibUtilities::EquationSharedPtr icond 
        = session->GetFunction("InitialConditions", "u");
    icond->Evaluate(x0,x1,x2,0.0,field->UpdatePhys());
}

Diffusion::~Diffusion

(

)

Definition at line 121 of file DiffusionSolverTimeInt.cpp.

{
    session->Finalise();
}

Member Function Documentation

void Diffusion::DoImplicitSolve	(	const Array< OneD, const Array< OneD, NekDouble > > &	inarray,
		Array< OneD, Array< OneD, NekDouble > > &	outarray,
		const NekDouble	time,
		const NekDouble	lambda
	)

Definition at line 151 of file DiffusionSolverTimeInt.cpp.

References Nektar::StdRegions::eFactorLambda, Nektar::NullFlagList, and Vmath::Smul().

Referenced by TimeIntegrate().

{
    StdRegions::ConstFactorMap factors;
    factors[StdRegions::eFactorLambda] = 1.0/lambda/epsilon;

    for (int i = 0; i < inarray.num_elements(); ++i)
    {
        // Multiply RHS by 1.0/timestep/lambda
        Vmath::Smul(field->GetNpoints(), -factors[StdRegions::eFactorLambda],
                                         inarray [i], 1,
                                         outarray[i], 1);

        // Solve a system of equations with Helmholtz solver
        field->HelmSolve(outarray[i],
                         field->UpdateCoeffs(),
                         NullFlagList, factors);

        // Transform to physical space and store in solution vector
        field->BwdTrans (field->GetCoeffs(), outarray[i]);
    }
}

void Diffusion::ExactSolution ( )

private

Definition at line 193 of file DiffusionSolverTimeInt.cpp.

{
    unsigned int nq = field->GetNpoints();
    Array<OneD,NekDouble> x0(nq), x1(nq), x2(nq);
    field->GetCoords(x0,x1,x2);

    LibUtilities::EquationSharedPtr ex_sol =
                                session->GetFunction("ExactSolution",0);

    if(ex_sol)
    {
        // evaluate exact solution
        Array<OneD, NekDouble> exact(nq);
        ex_sol->Evaluate(x0, x1, x2, (nSteps)*delta_t, exact);

        // Calculate errors
        cout << "L inf error:      " 
             << field->Linf(field->GetPhys(), exact) << endl;
        cout << "L 2 error:        " 
             << field->L2(field->GetPhys(), exact) << endl;
        cout << "H 1 error:        " 
             << field->H1(field->GetPhys(), exact) << endl;
    }

}

void Diffusion::TimeIntegrate

(

)

Definition at line 126 of file DiffusionSolverTimeInt.cpp.

References DoImplicitSolve(), Nektar::LibUtilities::GetTimeIntegrationWrapperFactory(), Vmath::Vcopy(), and Vmath::Zero().

Referenced by main().

{
    IntScheme = LibUtilities::GetTimeIntegrationWrapperFactory().
                    CreateInstance(scheme);

    ode.DefineImplicitSolve(&Diffusion::DoImplicitSolve, this);

    // Initialise the scheme for actual time integration scheme
    u = IntScheme->InitializeScheme(delta_t, fields, 0.0, ode);

    // Zero field coefficients for initial guess for linear solver.
    Vmath::Zero(field->GetNcoeffs(), field->UpdateCoeffs(), 1);

    for (int n = 0; n < nSteps; ++n)
    {
        fields = IntScheme->TimeIntegrate(n, delta_t, u, ode);
    }
    Vmath::Vcopy(field->GetNpoints(), fields[0], 1, field->UpdatePhys(), 1);

    WriteSolution();
    ExactSolution();

}

void Diffusion::WriteSolution ( )

private

Definition at line 177 of file DiffusionSolverTimeInt.cpp.

{
    // Write solution to file
    std::vector<LibUtilities::FieldDefinitionsSharedPtr> FieldDef
                                                = field->GetFieldDefinitions();
    std::vector<std::vector<NekDouble> > FieldData(FieldDef.size());
    for(int i = 0; i < FieldDef.size(); ++i)
    {
        FieldDef[i]->m_fields.push_back("u");
        field->AppendFieldData(FieldDef[i], FieldData[i]);
    }
    fld->Write(session->GetSessionName() + ".fld", FieldDef, FieldData);

}

Member Data Documentation

NekDouble Diffusion::delta_t

private

Definition at line 74 of file DiffusionSolverTimeInt.cpp.

NekDouble Diffusion::epsilon

private

Definition at line 75 of file DiffusionSolverTimeInt.cpp.

MultiRegions::ContField2DSharedPtr Diffusion::field

private

Definition at line 65 of file DiffusionSolverTimeInt.cpp.

Array<OneD, Array<OneD, NekDouble> > Diffusion::fields

private

Definition at line 70 of file DiffusionSolverTimeInt.cpp.

LibUtilities::FieldIOSharedPtr Diffusion::fld

private

Definition at line 62 of file DiffusionSolverTimeInt.cpp.

SpatialDomains::MeshGraphSharedPtr Diffusion::graph

private

Definition at line 64 of file DiffusionSolverTimeInt.cpp.

LibUtilities::TimeIntegrationWrapperSharedPtr Diffusion::IntScheme

private

Definition at line 67 of file DiffusionSolverTimeInt.cpp.

NekDouble Diffusion::lambda

private

Definition at line 76 of file DiffusionSolverTimeInt.cpp.

unsigned int Diffusion::nSteps

private

Definition at line 73 of file DiffusionSolverTimeInt.cpp.

LibUtilities::TimeIntegrationSchemeOperators Diffusion::ode

private

Definition at line 69 of file DiffusionSolverTimeInt.cpp.

string Diffusion::scheme

private

Definition at line 72 of file DiffusionSolverTimeInt.cpp.

LibUtilities::SessionReaderSharedPtr Diffusion::session

private

Definition at line 61 of file DiffusionSolverTimeInt.cpp.

string Diffusion::sessionName

private

Definition at line 63 of file DiffusionSolverTimeInt.cpp.

LibUtilities::TimeIntegrationSolutionSharedPtr Diffusion::u

private

Definition at line 68 of file DiffusionSolverTimeInt.cpp.